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Topic Title: Double guessing my electrician
Topic Summary: Cable protection
Created On: 05 August 2012 12:09 PM
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 05 August 2012 12:09 PM
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Craig2432

Posts: 2
Joined: 05 August 2012

I have been using the electrician for several year and have been more than happy with his work.

We are in the process of moving our factory to a new site, which is an existing industrial unit. The unit has been completely gutted except for the existing lighting (low bay I think)

The existing lights are still partially wired. They are layed out in 5 rows of 6.

My question. The electrician is telling me that he cannot use the existing cable for 2 resons. 1. The cable is black and red. 2. The cable is cable tied to gurder clips at high level as it travels from on light to the next.

I am positive that this is how he has run other cables at our last site.

A I wrong to question his knolage or not.

Any feed back is most welcome
 05 August 2012 10:14 PM
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ectophile

Posts: 546
Joined: 17 September 2001

You might be better off asking this in the "Wiring and the regulations" section of this forum, as that's where the electricians hang out.

-------------------------
S P Barker BSc PhD MIET
 06 August 2012 07:46 PM
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Dave69

Posts: 447
Joined: 16 July 2011

nothing wrong with red and black cores within the existing cable as long as warning labels are fixed to the DB's etc.

I guess the lights are wired in twin and earth so how else are you going to fix the cables without using girder clips? I would love to see your sparks at the top of a tower using his hammer and some hit clips
 06 August 2012 09:55 PM
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GJH

Posts: 501
Joined: 24 January 2008

I wouldnt use T&E in an industrial unit to be honest.

Nothing wrong with it but can see where the electrician is coming from.
 06 August 2012 10:45 PM
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davezawadi

Posts: 2722
Joined: 26 June 2002

Exactly, nothing wrong with it. So no change required, but then this happens all the time, its money for nothing!

-------------------------
David
CEng etc, don't ask, its a result not a question!
 07 August 2012 08:50 AM
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broadgage

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Joined: 07 August 2007

Red and black insulated cables should not be used for new installations, but there is no probibition on existing red and black cables remaining in use if otherwise suitable.

I do not much like the idea of twin with earth cables in industrial situations, but would consider them probably acceptable for lighting if well out of reach.

The use of plastic cable ties to fix cables to the structure is not so far as I know prohibited by the IET regs.
It is however poor practice for another reason. In case of fire the plastic cable ties will melt in seconds and result in long loops or festoons of cables hanging down and seriously impeding the work of firefighters.
This objection may be overcome by the use of stainless steel ties.
There is no need for every cable tie to be metal, just say one in five or so to prevent long loops hanging down.
(the cable will be a write off in any case, the idea is not to preserve the cables but to facilitate firefighting and recovery)
 07 August 2012 11:06 AM
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spinlondon

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There is nothing preventing the use of red and black for live conductors, or in fact any other colour except the combination of green and yellow in a new or old installation.
The prohibition against green and yellow only applies to single core cables.
The cables are required to be identified correctly at their terminations.
This can be either by colour or alphanumeric marking.
 07 August 2012 11:53 AM
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potential

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Originally posted by: spinlondon

There is nothing preventing the use of red and black for live conductors, or in fact any other colour except the combination of green and yellow in a new or old installation.

The prohibition against green and yellow only applies to single core cables.

The cables are required to be identified correctly at their terminations.

This can be either by colour or alphanumeric marking.


I agree.
Also the OP has not specified what type of cable is installed.
therefore it is not known if it is T&E or not.
 07 August 2012 08:06 PM
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Craig2432

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Thanks for the feed back.

I have checked his quote and the cable in guestion is 4mm twin and earth, and to answer two further question, yes the cable is for lighting and yes it is well out of reach ( may be 30 feet up)

It's interesting that Davezawadi says that this happens all the time it's just money for nothing.

Do you think I should start looking more closely at his quotes and more importantly how do I question some one I'm paying for his technical skills?
 07 August 2012 09:16 PM
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hifly

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Originally posted by: Craig2432

Do you think I should start looking more closely at his quotes and more importantly how do I question some one I'm paying for his technical skills?



you get another quote or 2

-------------------------
Vince

Prove Dead Stay Alive


 07 August 2012 11:10 PM
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OldSparky

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Joined: 28 June 2011

he could be trying to give you a good job, he could probably respect you as a good customer and be trying to ensure he does everything correctly..

but as the others say there could be no reason to change the existing.. try having a chat and get him to explain
 08 August 2012 08:39 AM
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davezawadi

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I'm afraid I don't agree OldSparky. Deciding what needs to be done is pretty specific if you are competent, fair, and above all honest. The difficult areas are not cable colours, or even erection or selection criteria, but whether to recommend changing luminaries to save electricity, illumination levels for safe working, and whether CPDs and RCDs are to be trusted after many years of sitting in a hot DB!
So in this unit (without seeing it of course) my first reaction is new lamps in all the fittings (probably HQI) and check the light level, a thorough inspection of the existing fuseboard and consideration of its status, check that all the cables have been properly disconnected and preferably removed, and a proper discussion about the new loads, and how these should be connected to the supply. If you need accurate work you may need more or different lighting, it could have been a warehouse with low lighting intensity or a clothing manufacturer with high levels, what do you need?

Effectively you have a new installation, and the design needs to be completed before starting any installation work, otherwise you will be trying to change the lighting with the place full of machinery, which is expensive and difficult! Multiple quotations against a design (or at least a specification of requirements) is always a good idea.

-------------------------
David
CEng etc, don't ask, its a result not a question!
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