Sunday, October 11, 2009

Temporary electrical panel and cords pictures

Below you'll find a few pictures on temporary electrical panels, sockets, power plugs and extension cords. I have added comments below the pictures on aspects that I think are important. Further comments will be added when I think of something readers may be interested to know.

Remember that I am sharing pictures of real electrical installations at real construction sites. This is the way I share my knowledge and my experience with the readers.

Beginners, please take note. Whatever are shown on all these pictures are materials for you to see and think. Maybe also for references in your own works, or in engineering classes.

Just because I show a picture here does not mean I am recommending a way or a method as shown in the picture, unless I specifically say so.

Picture 1

Temporary Electrical Panel Image 1

===== RELATED ARTICLES:  Temporary electrical installation pictures  |   Temporary Electrical Earthing Pictures |  1-Phase ELCB Connection Pictures  |   Temporary Electrical Earthing Pictures  |

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Picture 2
Temporary Electrical Panel Image 2
Picture 3
Temporary Electrical Panel Image 3

Is there anything wrong with the electrical installation in these pictures? The temporary panel seems to be quite new and definitely in a good condition.

You may question about the mounting method for the panel. But this is a temporary panel for a construction site.

At times, the subcontractor need to move the panel from one place to another every few days.

So fixed wall mounted method is not a practical choice this circumstances.

Yes you may want to suggest that the mounting stand be made of a much better material and design. That I would agree.

The supply cables to the panel seem to be four single core cables. I don't know what size just by looking at the cable from a distance, even though an electrician might be able to give a good guess. Four core means three phases plus one neutral.

You can also see two very good-looking wires with green insulation twisting along the four-cable bunch.

These must be the earthing wires, or Circuit Protective Conductor to be precise.

Is the total cross section sufficient of the earth wires sufficient?

I am a bit rusty on this nowadays. But temporary electrical supply only need residual current protection as the shock protection.

The green wires seem like 4 square mm. Two of them will give 8 I think that should be enough.

Of course the required cross section of the earth cables depend on the distance of the temporary panel to the earth electrodes.

That basically covers the electrical panel and the incoming supply cables. Now lets look at the outgoing circuits from the panel.

First the socket outlets, or the receptacles as the Americans say it.

They seem to have the original SIRIM sticker on each of the sockets. In any case, all the sockets are new, so there should not be much issue about them.

However, what has been plugged into each of the sockets is a different matter.

The appliance connected to the right socket of the lower row should be okey. I think it's the charger for a walkie-talkie. All factory manufactured and all new.

However, the cords connected to the other four sockets may have some serious safety issues. I will add comments on these in the near future.

Have a nice day.

Update February 2010:

I have these pictures of a temporary supply assembly hanging around at my old blog which is not very active anymore. I thought maybe it is better to put it here so it can be of benefit to someone.

Below are the pictures of the temporary electrical assembly. It was taken at one of my projects a few years ago.

What you see in the picture is the floor temporary sub-switchboard, which sits on the left of the assembly.

Next to it is the temporary DB with an on-board three phase isolator and a few 13A switched socket outlets.

Picture 4 – Temporary supply panel

Picture 5 – DB earthing busbar

Picture 6 – Three-phase temporary ELCB

The project was a multi-storey residential building and the temporary supply was taken from the temporary main switchboard at the ground floor.

The authority's meter panel was installed at the main switchboard.

So twisted 4-core submain cables was run from the main switchboard to each sub-switchboard at individual floors (one sub-switchboard for every three floors actually).

Since it was a 21-storey condominium, seven sub switchboards were installed.

From each sub-switchboard, cables were run at high level to distribution boards at various locations at the three floors in its coverage.

Back to the picture… So, what is so special about the electrical board assembly in the picture?

This is one example of the usual practices in the installation of temporary electrical supply at construction sites in our country.

Not all construction sites are like this example, of course. Many job sites practice very good safety standards and I can personally testify to that, but quite frankly the practice shown in the picture is quite common.

In this case, I have seen one situation that I have never seen. The picture may not be very clear, but I hope you can see that the incoming cables to the floor sub-switchboard are only four-core.

It has NO EARTHING at all.

I joined the supervision team while the work was already quite advanced with only a few month left to the completion. The temporary electrical supply has been in operation for almost a year.

The electrical sub-contractor has also been on board for many weeks. Yet, the electrical supply distribution from first floor to top floor at Level 21 has no earthing.

I was shocked when I notice this on my second day at site. It was unbelievable. Some unlucky workers could have died from this oversight.

The 25 by 3 mm earthing copper tape was finally installed later, after many days of my urging them to do it. The distribution boards and the temporary cabling were also much improved.

Note that the 3-phase ELCB already has a label below the TEST pushbutton that says “Test Monthly”.

I do not know whether anybody actually did the test or not, but if they did, the test by the ELCB pushbutton would not be able to detect a missing earthing connection. Read this post, 1-Phase ELCB Connection Pictures, to know more.

As you can see, apart from the earthing conductor, obviously a few more things were wrong with the distribution boards, the cabling and the plug and sockets in the picture.

Maybe we can talk again about these in my future posts.

For now, I just wish to emphasize the importance of checking the temporary electrical supply installation at your construction sites.

Do not assume that the main contractor of a RM230 million building project will have enough people to look at safety matters as important as this one.

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Maximus Prime said...

Don't u mean 4 Core is 3-phase and 1 neutral..

Wan said...

Thank you, Maximus.
It's a typo error. I've fixed them.

Thanks again.

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