Underfloor trunking below structural rebars

Below is a picture of a somewhat "improvised" installation of underfloor uPVC trunking within the structural rebars of a floor slab in a workshop building under construction.

Picture 1: uPVC trunking installed below structural rebars

===== RELATED ARTICLES: Underfloor trunking pictures | MATV trunking riser |   Conduit to trunking connections |  Cable ladder pictures | Electrical conduits and trunking pictures | Electrical panel under water pipes  | Electrical busduct installation pictures | Electric conduit installation pictures  | Electric trunking installation pictures | Site-fabricated electrical trunking | Electrical installation pictures

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I have published quite a number of pictures on underfloor trunking systems.

Below is an example which was been posted in May 2010.

Picture 2: An under trunking system at a highrise office building



These underfloor trunking systems, together with their floor draw boxes (i.e. junction boxes) and floor service boxes, have so far been installed inside the concrete screeding of the concrete floor.

In this installation method, the reinforced concrete floor slab is constructed first.

However, the construction of the concrete floor is not yet completed with the completion of the reinforced concrete.

A layer of concrete 50mm to 75mm thick is to be poured and leveled on the finished reinforced concrete to make a finished concrete floor. This layer is called 'concrete screeding'.

It is within this top concrete layer that an underfloor trunking system is installed, or "embedded" as some people call it.

However, in the new picture that I showed above, the underfloor trunking is not installed in the screeding layer (In fact there is no screeding layer here).

The finished floor level here has been designed to be just 50mm above the top of the top of topmost reinforcement steel bars (called "rebar").

With the size of the uPVC trunking of 75mm wide x 25mm height, there would only be "approximately" 25mm thick of concrete above the uPVC ducts.

This concrete thickness is insufficient and it can eventually crack even in a "light duty" environment such as office floor. It will not last very long here ... it's a workshop.

So in this case the contractor had no choice but to install the trunking between the steel rebar mesh. If it had been two layers of reinforcement provided, then the trunking would be installed between the layers.

Picture 3: Close view of a service box opening

As you can see there are also added reinforcement bars around the opening for the underfloor service box.

When I took this picture the structure engineer has not yet inspect the underfloor trunking installation work.

They have inspected them once and had a few major comments.

One of the comments that I wish to share with you is that the uPVC trunking should not be touching the steel reinforcement bars.

The photo below shows how the installation was before it was corrected.

Photo 4: uPVC trunking touching steel reinforcement

At the areas where the trunking touches the rebars, the grip of the concrete material onto the reinforcements would be weaken. This may weaken the strength of the finished reinforced concrete.

How much weaker? Well, I did not really ask. My guess was that even the site structural did not really know "how much weaker".

Photo 5: The corrected trunking installation

In the above picture, the trunking installation was adjusted to leave some gap of around 15mm or more between the trunking and the steel reinforcement.

You can still see the rust marks on the trunking where they touched each other earlier.

Beginners please do not get confused here. The white rectangular boxes connecting the underfloor trunking are not the real underfloor junction boxes or service boxes.

They are just some polystyrene foam materials (the same material some people uses as refrigerator insulators) that are used to create openings for the real junction and service boxes that will be installed at a much later date.

If the contractor installs the boxes now, they will be damaged in a very short time.

OR STOLEN! ... I can almost feel some readers quickly nodding their heads in agreement ...

Okey guys. This is all I can write today. I will post a few more other pictures on this soon.

Copyright http://electricalinstallationwiringpicture.blogspot.com Underfloor trunking below structural rebars

Conduit to trunking connections

I attach here a few pictures showing the connections between electrical conduits and trunking. Some few weeks ago a reader left a message on one of my blogs asking how to connect a branch conduit to a steel trunking. So these pictures should be self-explanatory enough how to make the connection.

Picture 1 – Electrical and mechanical services above the ceiling of an office building

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RELATED ARTICLES: Underfloor trunking below structural rebars |  MATV trunking riser |  Cable ladder pictures |  Electrical conduits and trunking pictures | Electrical panel under water pipes  | Electrical busduct installation pictures | Electric conduit installation pictures  | Electric trunking installation pictures  | Electric Panel Installation Pictures  | FR electric cable installation pictures  | Multi storey building electric closets  | Underfloor trunking pictures  | Site-fabricated electrical trunking  | Electrical Services Color Codes  | Light switch installation pictures | Building’s electrical rooms layout | Electrical installation pictures
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The above picture shows some of the services inside the ceiling space of and office building.

Here you can see some conduit and trunking works. For large office floor space, conduit alone is usually not enough to contain the wiring cables from the floor distribution panels to the lighting and power points.

However, it not practical and a sheer waste to use trunking up to a final circuit point, a light point for example.

A lighting point needs only three wires of 1.0 mm.sq. or 1.5 mm.sq. to make a complete wiring. This does not need a trunking. It is also difficult to connect a trunking to a lighting fixture.

Therefore, the wiring to the lighting point needs to be routed into a conduit. The best is flexible conduit.

The following two pictures show how a trunking branched into rigid and flexible conduit.

Picture 2 – Conduit branching into rigid metal conduits

The above shows two branches into rigid steel conduits. One using a circular draw box as an adapter, and the other is connected directly to the metal trunking without any drawbox.

Either one is fine, but if you have a number of circuits to be run into the branch conduit, then using the draw box might me more preferable. It would ease the work of drawing the wire.

If the tap off needs to supply only one lighting point, then you can save one draw box by connecting the trunking to the conduit directly.

Another reason for using the draw box is when the conduit do not connect to the trunking at 90 degree angle to the connected side. In that case, you definitely need the draw box.

In any case, the conduit and trunking works is a skilled tradesman’s work. Often many aspects of the actual installation tasks require some creativity and experience to do it properly at a reasonable cost.

If some tradesman have a long list of better ways to do this connection than the ones that I show in this post, then by all means follow him.

What I show here are those that are usually practiced locally here.

Picture 3 – Another two connections at the same location

One more important aspect of the connection between the electrical trunking and conduit is how exactly to fix the two pieces of electrical container.

It is not visible how it is done from the above three pictures. I also keep forgetting to open up an electrical trunking and take the picture of the connection inside the electrical trunking.

The third piece of the component that makes up the connection is only visible from inside the trunking which I presently do not have any picture.

However, there is one place where it is easier to see that third component. It is at the connection between a rigid electrical conduit and the concealed metal box of a socket out or a wall mounted light switch. The pictures below show this quite clearly.

Picture 4 – Connection between rigid electrical conduit and a concealed metal box

I have labeled the relevant components so you can see clearly what are involved in the connection between the conduit and the concealed box.

The “copper bush” is the component that I wish to show you. It is this same component that is used between conduits and trunking. When the conduit and trunking are made of metal materials, the “bush” is usually of copper material. This provides a good electrical connection between the conduit and the trunking.

On the other hand, if the conduit and trunking are of plastics or PVC materials, which are also quite commonly used in certain types of electrical installations, then the “bush” would be made of plastic or PVC.

The functions of the copper bush are three fold: one is to keep the connection firm and strong. The second is to provide a smooth finished that would not injure the insulation of wiring cables when they are drawn through the joint or connection. Lastly it serves to provide a good electrical continuity between the trunking and the conduit.

The following three more pictures give more view of the copper bush.

Picture 5 – A closer view of the copper bush in Picture 4

Picture 6 – Copper bush at another lighting switch with some wiring being installed

Here I use a picture that has some wiring already drawn in to show you how wiring cable can be damaged if the area around the connection is not smooth enough.

Copyright http://electricalinstallationwiringpicture.blogspot.com Conduit to trunking connections

Electrical Services Color Codes

The following set of pictures gives some examples on the identification of the different electrical services inside a building.

Picture 1 – Example color codes for a few electrical services

=========  RELATED ARTICLES: MATV trunking riser  |   Lighting flexible conduits |  CCTV conduits color coding | Cable ladder pictures |  Electrical conduits and trunking pictures | Electrical panel under water pipes  | Electrical busduct installation pictures | Electric conduit installation pictures  | Electric trunking installation pictures  | Electric Panel Installation Pictures  | FR electric cable installation pictures  | Multi storey building electric closets  | Underfloor trunking pictures  | Site-fabricated electrical trunking   | Light switch installation pictures | Electrical installation pictures
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The three conduits with the color code bands in the above pictures are part of what we call in building works as electrical services.

However, electrical services are not the only ones that require some means of identifying what they are for.

Mechanical services also really need their piping, trunking, etc to be provided with some identification.

In some installations such as hospitals, there are so many services under the mechanical category. At certain locations in a hospital complex, it is almost impossible to know which pipe is for what. (Remember that an electrical G.I. (galvanized iron) conduit is just a metal pipe.)

During maintenance, long after we the construction people have completed and commission the building with all the mechanical and electrical services fully tested and operational, the maintenance people could be cursing us every week for not providing sufficient identification for each of the services inside the building.

During operation and maintenance of the building, insufficient identification on each of the services throughout the building can lead to serious accidents.

Why do I talk about mechanical services? Because they often run along the electrical services. Now and then the parts and materials between the two disciplines look and feel just the same.

A note for the beginners: the different colors of the wires to a three-phase motor or to a machine that use three-phase power supply is a form of color coding.

Now let us get back to the pictures: In Picture 1 above you can see three conduits with color bands on them.

The one the right side (nearer to the concrete wall) has got a six-inch band with two colors. Or you can call it three bands with the outer two in red and the center band in white.

This conduit is for one of the Extra Low Voltage services. It is for the audio-video cables. An example where you can find this would be a large meeting room or a conference room, or an auditorium.

These types of building spaces would usually have conduits and/or trunking to contain and protect the wiring cables to and from the microphone points, the speaker points, ceiling speakers, etc.

That is an example of what we call an Audio-Video system.

(Note: Extra Low Voltage (ELV) Services is a name usually used to categorize some electrical services. Examples may be the Audio-Video system I have just explained above, security systems like CCTV and card access systems, queue management system, etc. These systems are still electrical systems because they still run on voltage and currents to say it simply. However, they use very low voltages of less than 25 volts anywhere in their equipment and wiring.

Of course they still need to connect to the 240 volt building electricity in order to work.)

The purpose of the color bands is simple: to identify what system the conduit is part of.

Table 2 below show a table of the ELV services in a building with the respective colors of the bands shown.

Not all buildings use the same colors, but large organizations usually have some sort of standard color coding system that must be followed by all contractors that execute work under the control of that particular organization.

Table 2 – Table of color codes for ELV services



Note that the colors for electrical conduits and trunking are not listed here. As far as I know it is a general practice everywhere to use orange as the color code for those electrical conduits, trunking and cable trays, while the cable ladders are more often not painted.

The subject of color coding is simple so I am not going to drag this post any longer than necessary. Readers can just scan through the other pictures below.

Picture 3 – Labeling on electrical trunking

Any building of a signification size usually has a supply source backed by standby diesel generators. This supply is usually called “ESSENTIAL SUPPLY”. The label “ESS” spray-painted below the smaller trunking is used to convey that message.

In office buildings, a form of centralized UPS (uninterruptible power supply) may also be provided. In Picture 3 above, the trunking that carries the wiring to all 13A wall sockets backed a UPS supply has been labeled “UPS”.

Please do not underestimate the importance of these labels. When the electricity supply from the public mains has failed, the standby diesel generators kick in. So the cables and wiring that run inside the ESS trunking is LIVE.

That means all socket outlets supplied from this trunking is still live and DANGEROUS.

The UPS unit always takes supply from electrical boards backed by the generators. So the wiring inside UPS trunking are also just as dangerous.

If the standby diesel generators also fail to start, then the wiring inside the ESS trunking has no power and not live.

However, the wiring inside the UPS trunking still has power because they are backed by batteries of the UPS unit.

Picture 4 – Another picture of electrical trunking

Picture 5 – CCTV conduit



Pictures 6 – Conduits for some other ELV services. You can check against Table 1



Picture 7 – CCTV conduit also



Picture 8 – Audio-video system



Picture 9 – This is another method to label the ESS supply




Okey folks… I need to get back to my work. See you again the next time.

Visit this post, Electrical installation pictures, to see more electrical pictures.

Copyright http://electricalinstallationwiringpicture.blogspot.com Electrical Services Color Codes

M & E Coordination

The few pictures that I show in this post is a demonstration of what can happen when proper coordination drawings are not produced prior to the commencement of the mechanical and electrical services installation in a multi-storey building.

Picture 1 – Improvised installation of electrical trunking, air-conditioning ducts, fire protection pipe work and a floor beam



===== RELATED ARTICLES:

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Somewhere among my previous posts, you can find examples of good coordination between the mechanical and electrical services installation.

However, here I wish to show you the opposite side of it. The above is not the worst case examples. I have plenty of pictures showing much worse scenarios which I will show you in future posts.

A reminder for the beginners in electrical installation works: Learn from the mistakes that other people have done and plan your work accordingly.

This is a very expensive lesson if you have to learn it from personal experience because rectifications, relocation or corrections in large installations can be very expensive and time consuming.

I do not plan to make this a long article. Regular visitors to this blog may have noticed that I have not been posting for quite a number of months.

A few have been asking me to continue posting articles and adding more topics.

So today I am back and you can expect to see some more pictures of electrical installations, good and bad.

There are readers who condemned a few of the pictures that I use to explain something.

They seem to have the opinion that using pictures with bad installation practices is like promoting bad installation practices.

With all due respect to their experience and expertise, I beg to differ on this matter and I think many would agree with me.

I also wish to remind the readers that none of the electrical installation works published here is my handiwork, whether the good ones or the bad ones. I did not do the wiring work; I did not do the trunking installation, etc.

I might have been the inspector with the responsibility to inspect or audit some the installation works.

However, when I show a picture, it does not necessarily mean that I say “this wiring work is a good example”. Or it is bad, unless I specifically say so.

It only means that there is something that the readers can learn from the picture.

Please bear in mind that different readers may learn different lessons from one single picture.

One of the primary objectives of this blog is to educate common people in how electrical installations work in real life. That is why I use “real” pictures.

In real life, the “real installations” (such as one’s own house wiring) are often “not that neat” and not that pretty.

It is very easy for me to show you pictures of neat and orderly house and office installations. I work in the construction business and I have tons of pictures of neat installations like that.

However, people often find it hard to understand the actual wiring in their own house or their own small offices because in most cases the wiring works are not new. They have been modified and they have been tampered with by people who either didn’t know enough or didn’t care enough about safety, or he tried to make the wiring works at a very low cost.

Whatever the reasons for the bad practices, the occupant who inherit the unit is faced with a wiring “system” that is hard to understand and is full of bad practices.

It is for this very reason that I use these pictures to explain how the wiring works. They are “real”.

That is all I have time for today. Enjoy the pictures and see you again in the next post.

Picture 2 – Electrical trunking and air-conditioning ducts



Picture 3 – Sprinkler pipes and trunking



Picture 4 – Telephone trunking, electrical and aircond duct



Picture 5 – Sanitary piping and domestic water pipes above electric trunking



Picture 6 – Sanitary pipes above electric trunking



Picture 7 – Trunking below sprinkler pipes



Picture 8 – Trunking below water piping



Picture 9 – Water pipes above trunking



You can see more pictures of electrical installation at this post, Electrical installation pictures.

Copyright http://electricalinstallationwiringpicture.blogspot.com M & E Coordination

Site fabricated electrical trunking

What will be the problem if an electrical contractor fabricates the electrical trunking at the construction site? Why do I make an issue of this matter?

Picture 1 – Electrical trunking already installed at a new building under construction



=========  RELATED ARTICLES: Underfloor trunking below structural rebars | MATV trunking riser |   Conduit to trunking connections |  Cable ladder pictures |  Electrical conduits and trunking pictures | Electrical panel under water pipes  | Electrical busduct installation pictures | Electric conduit installation pictures  | Electric trunking installation pictures  | Electric Panel Installation Pictures  | FR electric cable installation pictures  | Multi storey building electric closets  | Underfloor trunking pictures    | Electrical Services Color Codes  | Light switch installation pictures | Electrical installation pictures 
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Majority of Clients and Consultants that I know specifically state that all electrical trunking and the related accessories should be factory-manufactured and should preferably be obtained from the same manufacturer.

This means that all parts and pieces that make up an electrical trunking installation should purchased as finished products from factory.

Observe from Picture 1 above that one of the electrical trunking has been bent. That was to make room for something else that would be installed there later (it was not yet installed at the time this picture was taken. I am not yet very sure myself what that something is… which reminds me that I need to check it out soon).

The point here is that now and then electrical trunking need to bend and turn around things and other services and equipment along their path inside a building.

Because of that, we need the angle pieces of the trunking.

However, fabricating an angle piece from a straight trunking piece is the most economical alternative for many electrical subcontractors. That is why many of them usually try very hard to use this alternative rather than buying them ready-made from factory as specifically required by the Contract Specifications.

I was once faced with a contractor who just bulldozed their way and installed the site-fabricated trunking bends for eleven of the twenty floors of an office building.

The contractor thought he could play hardball and force me to accept and approve the installation.

Too bad he lost the battle in the end and he had to spend all the manpower and the extra “factory-manufactured” materials to redo the trunking installation.

The worst thing was that all the wiring had already been installed.

The three pictures below show a trunking bend being fabricated by the electrical worker at a construction site that I was involved in.

I rejected these works also and the rectification work should be done by the electrical subcontractor. The contractor knew I would not accept this sort of quality, but he thought he was smart I guess.

Why such a big fuss over this matter?

Because the site fabricated trunking accessories are almost always of very poor quality. The finished product usually produces very sharp edges all over the piece.

The sharp edges cut into the insulation of the wiring cables during the cable installation. When the insulation is damaged all over the place along the length of a cable, then it is no longer a good cable no matter how much you paid for it.

Wiring cables that have been damaged in this way not only become a maintenance headache to the operation people after just a few years, they are also dangerous and can cause deadly electrical accidents.

I say it again: THEY ARE DANGEROUS AND DEADLY.

Picture 2 – 45-degree trunking bend



Picture 3 – Sharp edges of the trunking bend



Picture 4 – Site workbench where the trunking “accessories” are “manufactured”



That is all the time I have for this blog today. Visit this post, Electrical installation pictures, to see more pictures of electrical installations.

There are other posts that I have sent a few months back about electrical trunking installation. You need to browse around this blog see them. I will put their direct links to this post in a few days for the readers’ convenience.

One last note: I wish to apologize to my regular visitors for being away this past few weeks. I know this blog has been getting regular visits from quite a number of readers.

The last few projects that I have been involved in have been taking too much of my time and energy, too much more than I would normally like to spend.

I also wish to thank the readers who have left messages. If you like these pictures, visit again.

I, however, will not be answering messages yet on this blog because I think this blog has not yet enough contents.

Not only that, once I start answering your messages, then I would feel very guilty when I cannot spare time on them.

Again thank you for visiting. I sincerely hope that pictures and other information that I put up here are useful to you all.

See you again soon.


Copyright http://electricalinstallationwiringpicture.blogspot.com Site-fabricated electrical trunking

Underfloor trunking pictures

The underfloor trunking system has been around for a long time. The first time I saw it was inside an application guide published by a public telecommunication company.

The technical manual was already very old and I was in the first year of real professional work after my graduation. That was 23 years ago.

Picture 1 – Underfloor service box installation in progress



===== RELATED ARTICLES: Underfloor trunking below structural rebars | MATV trunking riser |   Conduit to trunking connections |  Cable ladder pictures | Electrical conduits and trunking pictures | Electrical panel under water pipes  | Electrical busduct installation pictures | Electric conduit installation pictures  | Electric trunking installation pictures  | Electric Panel Installation Pictures  | FR electric cable installation pictures  | Multi storey building electric closets   | Site-fabricated electrical trunking  | Electrical Services Color Codes  | Light switch installation pictures | Electrical installation pictures
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Why do we need an underfloor trunking system?

An underfloor trunking system is an alternative way of providing the dedicated routes to run electrical cables, telephone cables or any other wiring cables you can think of.

I said wiring cables. An 11KV cable is not a wiring cable. A 25 sq.mm electrical feeder cable to supply an 11 KW fire pump panel is not a wiring cable.

(Note: 25 sq.mm means 25 millimeter square. It is a measure of the net cross-sectional area of the electrical conductors of an electric cable).

The 1.5 sq.mm cables that are used for wiring the office lights are categorized wiring cables.

The 2.5 sq.mm or 4 sq.mm cables used in socket outlet wiring are also categorized as wiring cables.

That is on the electric power cables.

On the telephone side, the telephone wiring cables going to each telephone outlet in an office area are also called wiring cables.

But an incoming 100-pair telephone cable from the public telephone company into a multi-storey office building is not a wiring cable.

Likewise, a Cat 5 computer network cables going to the office computers from the server rooms can be called wiring cables.

However, a multi-core fiber optic cables connecting two computer buildings cannot be called wiring cables.

So those cables categorized as wiring cables can be run inside the underfloor trunking system.

In fact, the underfloor trunking has been invented specifically for this purpose.

Why the special treatment is given to the underfloor trunking?

Why not use the normal conduit and trunking? (See the conduit and trunking pictures here: Conduit installation pictures; Electric trunking pictures.)

The underfloor trunking system was developed long before I started my career in electrical engineering.

However, I think I can guess why there was a need for this system.

The need arose because of the popularity of open office layout system in the design of buildings.

There is no doubt that many residential buildings also use underfloor trunking systems. However, these buildings do not really have to use this system. The normal conduit and trunking system would serve the purpose perfectly well.

However, in an open office system, it is difficult to bring the wiring cables to the working tables in the middle of an office space (i.e. away from the walls) without running the cables inside the floor.

With many tables away from the walls, then many trunking and conduit need to be cast into the concrete floor.

Furthermore, different types of cables (eg. electrical and computer network cables) need to be run in different trunking and conduits totally segregated from each other.

In the end there were many trunking and conduit running all over the place inside the concrete floor slab of an office building with the open office concept of design.

So gradually the underfloor trunking concept developed, naturally.

Picture 2 – The underfloor trunking installation in progress



This picture shows a stretch of underfloor trunking installation in progress.

Notice that the floor reinforced concrete slab has been cast. The underfloor trunking was laid onto the already completed structural slab of the floor.

After the underfloor trunking components that need to be cast in have been laid out and fixed, a layer of concrete (called screeding) is poured to the floor to a thickness of about 50mm.

This additional two inch of concrete would cover the trunking parts, but the junction box would be exposed for access.

The thickness of the concrete screeding should be enough to give strength (and therefore would not crack) at the thinnest areas, which are the areas above the trunking parts.

Observe the notes that I gave in the picture.

During installation, there is always some time lapse between the installation pf the underfloor trunking parts and the pouring of the screeding concrete.

During this time, the trunking, junction boxes and service boxes need to be firmly held in place temporarily.

Steel bands and lean concrete are used for this purpose.

The temporary cover for the junction box opening is installed to prevent the fluid concrete from flowing into it during the concreting work. This temporary cover is made of soft metals and is usually supplied together with the junction box or the service box unit.

Notice also that there are three lengths of trunking installed together. So it is a 3-compartment trunking system. It could have been a 4-compartment or 2-compartment.

Here the trunking material is made of high-impact PVC trunking. However, an underfloor trunking can also be made of metals.

What is the difference between a service box and a junction box?

I should have explained this earlier so that beginners do not get confused.

A service box is a box along the underfloor trunking where the user can connect to the power outlet, telephone socket and computer socket.

It is the point of “service”.

Picture 3 below shows how a service box looks like.

Picture 3 – An underfloor service box



While a junction box is provided to facilitate the drawing in of cables during installation and maintenance.

It is also provided where a trunking need to make a bend and where it branches off.

That is why it is called a “junction” box.

Picture 4 – A completed underfloor junction box



Observe that the completed junction box cover is firmly fixed with 4 mounting screws at the corners.

On the other hand, the cover of the service box is designed so it can easily be open frequently.

That is because the service box is designed for user access. This is where users plug in their appliances just like the wall sockets.

Picture 5 – Vertical access box



The underfloor trunking resides at the floor. However, the cabling inside the trunking must come from the distribution panels somewhere.

If the distribution panel is located at the wall, then there must be a connection between the trunking inside the concrete floor and those at the walls.

That is the purpose of the vertical access box in Picture 5 above.

Sometimes, the electrical distribution panel is located inside the electrical riser which is some distance away. Usually the most convenient method of running the main trunking by hanger brackets above the ceiling.

Then at convenient locations, a set of droppers are installed to connect to the underfloor trunking. This is shown in Picture 6 below.

Picture 6 – Vertical access connection to trunking above ceiling



Picture 7 below shows another view of a junction box and underfloor trunking installation is progress, before the floor concrete screeding was poured in.

Picture 7 – Junction box and underfloor trunking picture



Construction works are never free from errors. Picture 8 below shows that a finished floor had to be hacked in order to extend the wiring from a junction box to the dry wall.

Picture 8 – Wall socket wired from an underfloor junction box



This was actually a last minute decision that was made to add another general purpose electrical outlet to the wall.

Theoretically it is best to wire general purpose electrical sockets on walls from separate circuits (better still, from a separate section of the busbar inside the electrical DB) than those inside the underfloor trunking, which supplies the work computers and other high priority equipment.

This is because the general purpose sockets are those used for such things as electric kettle, vacuum cleaners and other similar appliances.

Defects and faults in these appliances can cause trippings of the earth leakage circuit breaker (ELCB) at the electrical distribution panel, which can cause annoyances and other more genuine problems. (See pictures of ELCB at this post, 1-phase ELCB connection pictures.)

Update (March 15, 2014):
I have in my collections a lot pictures of materials that have been delivered to construction sites for installation of electrical systems.

For a long time this matter has been tickling my thoughts when I search through the pictures to attach to my posts.

Such a waste. These pictures has been helping me a lot of my work. Surely it must be of value to many people out there who still have no chance yet to get involved in actual electrical installation works.

Of course I can just upload all these pictures into the internet. But I don't think Google's search engine is smart enough to understand pictures and choose the right one for web users who are looking for them. There are probably trillions and trillions of pictures on the internet.

I cannot really make much of an article from pictures of electrical materials still in the plastic packings. It is too difficult. It seems too trivial, and I am not a much of a writer in the first place.

Today it just clicked in my head that I do not really need to write articles for these type of pictures. I can just attach the related one at the end of a related post. That's it!

I only need to write a few words to accompany each picture. The original post already says enough.

So with this revelation I am going to expand all of my posts to include a new section called "MORE RELATED PICTURES".

There I will gradually attach related pictures with a short description for each picture. I somehow a story clicks in my brain, then you will see a short story about the materials in the picture also.

If not, then just the description of the materials.

xxx MORE RELATED PICTURES xxx

Picture 09 - uPVC duct materials for an underfloor trunking system installation

This is the first picture that I will attach to this post today.

If you observe carefully, the trunking material are still on back of the delivery truck.

These are 3 inch by 1 inch uPVC ducts if I am not mistaken. The picture was from one of my office building projects.

If you enlarge the picture, you may notice that there are water droplets on the materials.

Well, this is another aspects of electrical construction which is proper handling of materials and equipment during loading and unloading, delivery and storage.

In this case here, the delivery truck people did not seem to care enough to put the rain cover over the material.

This happen to be not an issue here because the uPVC material have not problem with rainwater such as this.

However, it was still not a proper way to delivery the materials to a client who pay good money for them.

One thing that I wish to say on this picture is that we should always witness the delivery, and unloading of materials to a project site.

There are many types of materials and equipment that can get damaged or deteriorate in quality considerable when not handles properly during delivery, loading / unloading, and storage.

If the damages are noticeable during inspection, then you only need to reject the materials or equipment. Then they can be returned back to the manufacturer or his supplier.

What if you did not notice anything and proceed with the certification for payment and later found out that the materials have been damaged?

They may be a difficult dispute over who caused the damages. I have been through this many times.

A manufacturer might say the materials have been damaged during the storage at the client's store.

Anyway, that is all I wish to say on this. I will upload other pictures the the underfloor trunking installation soon.

Copyright http://electricalinstallationwiringpicture.blogspot.com Underfloor trunking pictures

Electric trunking installation pictures

As will be shown by the pictures below, no electrical installation work of a significant size can be done properly without the use of an electric trunking.

A trunking is a larger size of a conduit. When you need to run a number of electric conduits along each other for a significant distance, then consider using a trunking in place of the conduits. There are so many sizes you can choose from.

Picture 1 – Electric trunking running below soffit of floor concrete slab



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This is an example of a trunking installation above ceiling level, under the soffit of the concrete floor slab.

I also labeled some of the other services there for the benefit of those non-electrical readers who need pictures like this for reference, to know what is what among the myriads of pipes and wires running above the ceiling level.

Notice the label “E” and “N” on the electric trunking. “E” means Essential Supply and “N” Normal Supply.

All large buildings need labels of some sort to distinguish two types of electric supply: the “normal” electricity supply and “essential” electricity supply.

The normal supply means the supply that is obtained from the public electricity supply. When the public supply fails, then your have a black-out.

If you live at a higher floor of a flat building, then you have to walk down the emergency staircase to leave the building.

That is why an “essential” supply is provided. This is normally generated by one of more standby diesel generators.

When the public supply fails, the standby generator automatically kicks in and provides the electricity to the building through the cables run inside the “E” trunking.

If you wall socket is supplied from these cable, then you have electricity even during a black out.

Picture 2 below shows how the electric trunking is installed at location like this.

Picture 2 – Hanger rod



Two hanger rods and a length of angle iron are normally used to support the trunking at these types of location. The angle iron can be as long as is necessary to accommodate the number of trunking it will support.

The hanger rods would be as long as needed to position the height of the trunking to a level that would necessitate a minimum number of bends.

Bends are more expensive than the straight piece regardless of whether you buy it ready made from factory or fabricated at the site from a straight piece.

Custom made at site means labor costs, which can even result in a much higher cost in the end.

So far all the clients of the projects that I was involved in did not accept custom made trunking bends. Neither do I.

Custom made bends tend to have sharp edges that injures the insulation and protective outer sheath of electric cables.

Injured cables can cause many problems during the operation of the installation even though they normally seem to pass all tests and inspection during construction.

I always warn contractors not to use custom made trunking or cable tray bends. When they have to, they are required to notify me or my staff in advance and specific locations where they are used should be identified and permission granted for each one on case by case basis.

Picture 3 – Vertically mounted trunking



This picture shows electric trunking when they are mounted vertically.

This installation was inside a fan room at the roof of a multi storey building. A number of electrical panels would be located on that wall later. That is the reason for the multiple trunking installed.

This room was basically a machine room. It housed many of the smoke control and ventilation fans of the building.

As usual, wiring to machines and electrical equipment requires frequent maintenance due to overheated cables, addition of new machines, replacement or upgrading to bigger machines, etc.

All these reasons require frequent troubleshooting and rewiring of electric cables. The use of trunking makes the maintenance and upgrading work much easier. That is why trunking are used in these sorts of locations even though there would only be just a few small electric cables to be installed inside them.

The following pictures show how the trunking are fixed to the wall, the types of mounting brackets used, etc.

Picture 4 – Mounting bracket for wall mounted trunking



The above picture and the one below show two types of mounting brackets. These two are the low cost types.

Picture 5 – Another type of vertical mounting bracket



Same method, only different materials.

The type shown in Picture 6 would cost more, but it can provided higher strength which is needed for long vertical trunking such as those inside electrical risers in a multi storey buildings.

Picture 6 – Mounting bracket for long vertical trunking



This type also is suitable for large trunking sizes, which can carry more cables.

Picture 7 – Trunking 90 degree bend



This is an example of a bend. This one was factory-manufactured.

Picture 8 – A hanger rod support bracket installed by the air-conditioning contractor



This trunking and the hanger rod support were installed by the air-conditioning contractor. It is exactly the same as the method used in Picture 2.

However, I show this picture for a different reason.

Notice the white label “AC” painted under the trunking. This label is painted to all electric trunking installed by the air-conditioning contractor to distinguish them from electrical trunking installed by the electrical contractor.

It is a common practice that all electrical conduit and trunking are required to be painted orange color.

An air conditioning system runs throughout all floors of a modern high rise building. The locations of air-conditioning electrical equipment are not restricted to just inside the AHU rooms of a building floor.

There are numerous fan coil unit (FCU) throughout the floor area. Where individual control of the air temperature and quality inside a room is required, an FCU unit is needed.

So, an electric circuit need too be run there.

Many times, especially in large buildings, the works of electrical wiring to all these air-conditioning electrical equipment are located inside the air-conditioning works contract.

If for nothing else, this arrangement eliminates many coordination problems that usually occur when too much interfacing is required between different trade contractors.

The electrical contractor is then just required to run supply cable to the main electrical panel of the air-conditioning system at each floor. The electrical panel and all downstream cabling and wiring are parked under the air-conditioning contract.

Neat.

Okay. This is all I have time for today. We will meet again in the next post.

Readers new to this blog can find more pictures by visiting this post, Electrical installation pictures. There you will find links to other posts that contain pictures on the topics that you are looking for.

That is faster than searching in the ARCHIVE sidebar.



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