FR electric cable install picture

The following few pictures show the installation of FR electrical cables. There is nothing special about the installation of the fire-rated (FR) cables. Even though these cables are a direct replacement of mineral insulated copper cables (MICC) for high-rise buildings, the installation here is the same as for normal XLPE or PVC-insulated cables.

Picture 1 – FR cables installed on tray



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This picture shows two circuits employing FR electric cables installed on a vertical cable tray. These cables were taken in a cable riser at a multi-storey building.

All these cables are single-cores. The circuit on the right (with the smaller cables) was supplying the lift motor room at the roof level of the building.

The copper tape on the right edge of the vertical cable tray is the common earth and it is connected to the main electric grounding bar at the LV Room on the ground floor of the building.

The LV Room houses all main switchboards (MSB’s) for the building.

The circuit on the left edge of the cable tray was supplying two fan rooms, which were also at the roof level.

The loads of the fan rooms were mostly electric driven motors that run fire protection fans. These include smoke spill fans, staircase pressurization fans, etc.

These fan loads are significantly large. That is why the cables are of bigger size than those for the lift motor room electrical panel.

The color of FR cables

You can see in the picture that all the outer sheath of the FR cables are red colored.

I think the manufacturer can manufacture the cables to any color you wish. In this project the red color has been chosen because these FR cables supplies the equipment of the building’s fire fighting system.

Red is the standard color code for all fire fighting and fire protection systems and equipment as far as I know.

Fire sprinkler pipes, wet riser pipes, hose reel pump control panels, etc are all painted with red color.

Standby electric generators are part of the fire protection system

All the FR cables in picture 1 are supplied from the Essential MSB (EMSB) inside the LV Room at the ground floor.

The electric supply of the essential MSB in turn is backed by the standby electric generator of the building.

For readers with minimal background knowledge in the design of high-rise buildings, a standby electric generator is part of the fire protection system of a high rise building. Many fire fighting equipment and systems depend on the electricity supplied by this generator (or generators, often more than one electric generator are needed when the building’s total floor areas are very large, or if the building complex is spread over a very wide land area).

Fire lift is a classic example. Even though lift are designed as a means of vertical transportation for multi-storey buildings, a minimum of one lift is required to be designed and equipped as a fire fighting lift.

That means to say one of the lift will be used by the firemen to fight fire during fire emergency.

That is why the cables that supply the lift electrical panel should have the properties that can withstand fire condition for a few hours. That is also the reason the cables supplying the lift panels in picture 1 are colored red.

Essential supply cables are also colored red

Because electricity supply from the standby diesel generators is part of the building’s fire protection system, it follows that all cables from the generators must be colored red. This is assuming that the building’s color code for fire fighting equipment is red.

However, the supply from the standby generators is not only used for the fire protection. There are also other types of equipment in the building that need supply from the generators for other reasons.

These are equipment, lighting and socket outlets that need to run even when the mains supply from the public supply network is down.

We call the supply to these types of equipment “Essential Supply”. It is an essential electricity need of the building. Which equipment, lighting and power sockets need to be provided with the essential supply is usually defined by the owner of the building, assisted by professional architects, engineers and building managers. That is why the advice of at least one of these professionals is always needed during the planning of any new building.
Even though the is not fire fighting equipment connected to a circuit supplying essential supply, the supply cables are usually colored red. This is the common practice.

FR cable installation pictures

The foregoing general brief was given to fill in the gaps some readers may have when looking at the pictures of FR cable installations in this post and in other posts here.

I would need a separate and dedicated post to discuss the fire-related electrical systems in building works, which I may actually do some time in the near future. However, for now let just stick to the pictures.

Picture 2 – More fire-rated (FR) cables



Here there are more FR cables in the electrical riser.

Actually, this electrical riser is at the same building, but it is in a different riser room.

This building actually has two tower blocks: one tall and one a lower tower attached to each other.

Most of the mechanical plant and fire-related equipment for the both building towers are located at the roof of the lower tower. The cables on this cable riser tray supply emergency power to the lower roof.

That is the reason you seem more FR cables here.

Separate supply cables for each fire fighting system

A note for genuine beginners: it is usually a common practice to install a totally separate supply circuit for each system of fire fighting equipment and other mechanical systems from the Essential MSB (EMSB) at the LV Room.

Even the earthing cables are usually independent. That is why you can see the smaller green cables bunched together with each of the four circuits in picture 2.

However, you do not see the green earth cables in Picture 1 even though there are 2 separate circuits going up to the roof.

You see, the designers were not being very strict here.

I personally supervised the installation in this project, but it was a design-and-build contract. In this kind of contract, the professional design consultants are part of the main contractor’s team.

Because of that, the consultants must support the main contractor’s continuing effort to reduce costs and maximize profits.

They call this “value engineering”.

I apologize for the “negative tone” there, but I have been involved in many “turnkey contracts” and “design-and-build contracts” either as design engineers, consultant’s project managers and construction supervision engineers.

I think I have earned the right to insert the “negative tone” there.

Picture 3 – Normal supply cables



This picture shows a circuit employing normal supply cables on a separate vertical cable tray alongside the cable tray carrying the FR cables.

Notice the 3mm x 25mm earthing copper tape clipped to the cable tray along the single-core cables.

The normal supply cables here uses XLPE type cables for all submain cables. Only the final wiring circuits were allowed to use PVC insulated cables.

What is a “submain” cable?

I bold this item for the benefit of beginners in electrical installation works and building services engineering.

A submain cable is a cable that feeds supply from the main distribution equipment of an electrical system to an electrical panel that further distributes that electric power to current-using equipment or other electrical panel downstream of the distribution hierarchy.

The term can actually be used rather loosely.

In contrast to this term, a final wiring circuit cannot be called a submain cable even though the circuit may use exactly the same type and size of cables.

A set of cables supplying power ‘into’ the main distribution board are usually called main cables. I think that is why the distribution cables coming out of the main switchboard are called submain cables.

There is nobody out there going around enforcing rules about what you should call these cables. It is just a widely practiced way of categorizing these cables in real installations. If you call them the way other people in the industry call them, then you are using the same language.

If not, other people may get confused about what you were trying to say. That’s all.

Picture 4 – FR cable termination to busduct feed in box



This picture shows the termination of a busduct riser.

A busduct is a set of electrical conductors (usually copper or aluminium conductors) enclosed inside metal trunking.

The assembly is usually factory-manufactured and sold in ready-made length complete with integral earthing conductors.

You only need to purchase the number of lengths necessary to cover the distance from the source of supply to the destination.

Bends and angle pieces are also available from the manufacturers.

If you wish to know more about busduct installations, read this post, Electrical busduct installation pictures. There are more pictures there too.

Picture 5 – Fixing of the FR cables to cable tray



There is nothing special about the cable tie used to fix the FR cables to the cable tray. It is just the same type used to tie normal supply cables (i.e. PVC cables or XLPE cables).

Steel bolt and nuts are used to hold and tighten the steel cable tie to the tray.

Picture 6 – Copper tape fixing to the cable tray



This is just a closer view to show how the 3mm x 25mm earthing copper tape is fixed to the cable tray.

It is actually not necessary to use separate copper tape or the green earth cables to provide the electrical grounding for the electrical system.

The steel wire armor of multi-core submain cables can also be used to provide the electric grounding path.

Proper calculations should be done however, in order to ensure the cross-sectional area of the conductor is adequate for the protection system to operate properly. Also to ensure the requirements of the relevant codes are complied with.

Using separate 3mm x 25mm copper tapes is widely practiced in good installations because it is easy to monitor the quality of the earthing system and minimize the possibility of the contractor doing “value engineering” to this most important part of shock protection in an electrical installation.

That is all the time I can spare today for blogging.

I will see you again in the next post.

If you need more pictures, just visit Electrical installation pictures. There are links there that will take you the various posts with the pictures you are looking for.


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Electrical busduct installation pictures

The following pictures show electrical busduct risers in actual installation.

Picture 1 – Typical busduct rising main at individual building floors



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The above picture shows a typical installation of busduct rising mains in the riser room at individual floor of a high rise building.

This picture was taken in the riser room at one of the upper floors of a high rise building.

From the picture you can see most of the major components of a busduct riser system.

(NOTE: for readers who are not from electrical disciplines, a “riser” is a feeding cable or pipe giving supply to upper floors of a multi-storey building.

In electrical works, a riser is a set of cables the supply the upper floors. The electrical distribution diagram in Diagram 3 may make you understand this better.

The feeding cables “rise” up straight to the top floor. Then at each floor a tap-off unit is connected so electricity can be supplied to that floor.

An alternative is to run one individual set of cables to each floor. Then there would be many cables that need to be installed the number of which is directly proportional to the number of upper floors.

One single set of bigger cables is always cheaper to install and much easier to handle.)

Observe that there are three tap off units there: two units of 60A three phase, and one unit of 100A three phase. The one at the highest position of the three is the 100A tap off.

Why three units?

There are actually three risers here: one for the “normal” main electricity supply. This supply is just the normal authority supply like the one you have in your house. The 100A tap off unit is for this riser.

The second tap off, which is one of the 60A units, is what is called “essential supply”, or “emergency supply”. It is a normal authority supply like the one you have from the 100A tap off unit above.

However, it is also backed by a standby diesel generator. This means that if the electricity supply from the authority distribution network fails due to problem with their underground distribution cables or whatever, the standby electric generator would kick in and switch in the locally generated electricity to this electrical riser.

Large capacity electric generators are expensive, however.

Therefore, it is not economical to supply all electricity needs in the building from this generator. That is why separate electrical risers are used, and the “normal” riser is not backed by the generator supply.

The third tap off unit (the second 60A unit) is for the air conditioning system.

It is quite common (and is considered a better design) to have a separate feeder cable for the air conditioning and mechanical ventilation (ACMV) system in a large building. That is the reason for the third electrical riser here.

One more point to note here is that some office buildings use the generator-backed supply (i.e. ESSENTIAL supply) to feed the electrical riser for the air-conditioning system.

With this arrangement, ACMV equipment that need to continue operating even during the mains failure do not need to be connected to “ESSENTIAL” supply riser, which is why it is given a separate riser in the first place.

Observe the large flexible conduits coming out from the bottom of the tap off units and connect to the orange-colored electrical trunking. Some installations use rigid metal trunking for this purpose.

Cables are run from a tap off unit into the flexible conduit to go to the orange metal trunking.

They run inside the trunking to connect to the respective sub-switchboard.

You can see only two sub-switchboards here. These are for the “NORMAL” supply and the “ESSENTIAL” supply.

The switchboard for the air conditioning system is normally located inside the AHU room of that particular floor.

From the sub-switchboards, separate outgoing cables are run inside the trunking to connect to separate distribution boards (DB) on that particular floor.

That is all that I wish to elaborate on Picture 1 above.

My intention is so that beginners in electrical installations can understand the major components that make up a busduct riser system.

Now let us look at a few electrical diagrams. The diagrams can give a more complete overall view of a simple electrical system in which a similar busduct riser forms a part.

While the busduct risers in Picture 1 are for a high rise office building, the following diagrams are for much simpler installations. They are for the nurses hostels at a hospital complex.

Even though electrical installations at hospitals are relatively much more complex than the office building above, the installation at their hostel and staff quarters buildings are usually very simple.

That is why I choose to use them here. My objective here is to give casual readers and beginners in electrical works an overview and general understanding of the basic functions and installation of a busduct riser system.

The actual electrical diagram used to construct the installation in Picture 1 might be too complicated for this category of readers. I do not wish to scare them away.

Diagram 2 – Part single line diagram for a multi-storey nurses hostel



This diagram is part of a larger diagram which is in Diagram 3.

Diagram 3 – The full layout of the single-line of Diagram 2



As you can see, you cannot read much of the labels and notes in Diagram 3.

I produced this JPEG graphic from an AutoCAD drawing files (i.e. DWG file format) which is probably the most widely used drawing programs in the construction industry.

I used the program’s BMPOUT command to produce a BMP file format form the DWG file format. Then I converted the BMP format into the JPEG file format using the Microsoft Paint program.

However, this method does not seem to be effective enough for AutoCAD drawings that have been produced for A1 or A0 printing as the original sizes.

If anybody here knows a better method, please let me know.

Okay. Let’s get back to the electrical single-line diagrams.

In Diagram 1, you can see that the hostel building is six-storey, which Ground Floor, then Level 1 to Level 5.

Usually for a building of this height, designers do not use busducts. However, they do in this case. Maybe that was because the project already used so many busducts at the main hospital complex and other (much higher) staff quarters buildings, it made sense to also use busducts here.

In any case, the components of the busduct system that you see in Picture 1 were used at each floor of Level 1 to Level 5.

However, at Level 1 you have one or two more components. Picture 4 below shows a view of the electrical riser room at Level 1 (the first higher level). It is the same building as that in Picture 1.

Picture 4 – A view of the electrical riser room at Level 1 (the first level above ground level



As you can see, there are definitely more components here that in Picture 1.

However, actually there are basically only two new components at each riser, which is the TERMINATION BOX (some people call it “FEED IN BOX”), and the incoming cables that terminate into the termination box.

Apparently there is an extra tap off unit here, but it is the same component type.

Observe the cables coming into the termination boxes.

The biggest termination box has cables with black insulation terminated to it, while the other two termination box has red cables.

The red cables are red-colored because they are fire rated cables. Remember the “NORMAL” and “ESSENTIAL” supplies that I explained above.

Why the generator-backed “ESSENTIAL” supply cables need to have red colored insulation?

It is because this supply is part of the fire emergency system of the building. Which means this part of the electrical installation system must also comply with the Fire Requirements of the Building Bylaws and the Fire Department.

A fire-rated cable must be able to continue operating for a certain number of hours during fire before it fails. This is the requirement. It used to be MICC (mineral insulated copper cables) cables that play this role, but now people use mostly the “fire-rated cables” for this purpose except in very special installation condition.

The fire-rated cables are cheaper, easy to install and maintain.

(See more pictures of fire-rated FR cables at this post, FR electric cable installation pictures.)

The black-colored cables are from the “NORMAL” supply. That means the other ends of the cables are connected to the “NORMAL SUPPLY” main switchboard.

While the red cables are connected to the “ESSENTIAL SUPPLY” main switchboard.

Which means the “ESSENTIAL SUPPLY” main switchboard is the one that is backed by the standby electric generator.

Is it too complicated? I hope not.

Even if it is, have no worry. I will spend a post or two on the overall system of electrical installation for large multi-storey buildings soon. Now I am actually building up section by section.

I will end this post by attaching a single-line diagram for a building similar to that of Diagram 4. However, this one used the normal cable riser instead of busduct riser. I hope the all readers of this post can locate the difference in the two diagrams.

There are also a few more pictures for the risers of Picture 1 and Picture 4. These pictures provide more information and better views for a few of the busduct components.

Diagram 5 – A distribution system using a cable riser instead of the busduct riser



Picture 6 – Another view of the busduct risers at riser room



Picture 7 – The front view of one of the 60A TPN tap off units



Picture 8 – A closer view of the vertical busduct showing the arrangement of the conductors inside



Notice that there are five conductors inside the busducts: the three phases, the NEUTRAL conductor and the EARTH conductor. The arrangements of the conductors are as shown on the busduct casing.

Picture 9 – A view of the cable entry into the feed in box and the connection of the equi-potential earth conductor



Observe that the copper tape was connected to a wrong place.

The metal plate where the cables are connected to is a removable plate. The copper earth tape should stay clear of this removable plate.

The tape should be connected to the main body of the termination box at a location where it is least likely to be disturbed.

This installation work was actually still in progress when I took these pictures. The copper tape connection was later rectified.

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