Why is it important to have earth wire run as bare, than insulated in a metal conduit

[Realstylz]

Somebody at my workplace is suggesting that there is no harm, but rather beneficial to run earth wire insulated in a metal conduit from customer cut-out to installation's earthing point, saying it would rather prevent corrosion. This has however met fierce resistance from the remainder of the team, who however, aren't putting across their arguments factually on the table.
Anybody with a supporting idea?

 

[Marvo]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

Unless it's running through a corrosive environment earth wiring you describe can be either insulated or uninsulated.

 

[Welchyboy1]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

Do you mean to an earth rod externally?

 

[Realstylz]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

@Welchyboy1, Exactly.
@Marvo Has there been no regulations insisting on the use of bare earth conductors lately, for such purposes?

 

[Marvo]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

What regs are you working to in Zim? As far as I know it can be either insulated or not.

*Edit* I've moved this to the 'Non UK Electrics forum because I assume you're not working to BS7671 17th edition.

 

[Adam W]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

I haven't really thought this through, but would you not earth the metal conduit anyway, making the insulation around the earth cable somewhat irrelevant?

 

[ian.settle1]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

What regs are you working to in Zim?.

Don't upset Mugabe or else regs:hanged::behead::2guns::83:

 

[Geordie Spark]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

Don't upset Marvo or else ....... :60:

 

[Engineer54]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

Why would you need any form of earth wire in an earthed conduit system anyway?? That's like buying a dog and barking yourself!! ....Totally Pointless!! lol!!

 

[Brightspark2]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

Why would you need any form of earth wire in an earthed conduit system anyway?? That's like buying a dog and barking yourself!! ....Totally Pointless!! lol!!

Barking mad some would say...

 

[gazj82]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

Why would you need any form of earth wire in an earthed conduit system anyway?? That's like buying a dog and barking yourself!! ....Totally Pointless!! lol!!

My mentor used to say "If you need to put a cpc in a steel conduit, then you CAN'T DO steel conduit!"

 

[shanky887614]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

My mentor used to say "If you need to put a cpc in a steel conduit, then you CAN'T DO steel conduit!"

Some specs/clients require it.

Think of the old conduit without adapters you would not be able extend cpc without running one in

 

[7029 dave]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

Some specs/clients require it.

Think of the old conduit without adapters you would not be able extend cpc without running one in

I would say all my conduit work I have done,has all called for cpc (spec required).

 

[gazj82]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

Of course fit a cpc if the spec asks for it even if it is pointless, if your accessories are mostly plastic it kinda makes sense to anyway. If your still into big MEM switch fuse's then it's a waste of copper imho.

 

[bobzzz]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

We would run cpc in metal conduit. We had a few houses where the conduit corroded away after about 30 years due to the location to the sea and a high water table.

In the old days in Southern Africa all house wiring were done in metal conduit without any cpc. This was a good system because back then all work had to be inspected by an town inspector before he would allow the power to the installation to be switched on. After 1992 the rules changed and qualified electricians could self certify their work. Unfortunately there are cowboy qualified people as well and we saw in some old houses where there were a mixture of metal and pvc conduit with no cpc. Which obviously means that the new parts did not have earthing.

The rule states now that the conduit system must be earthed, but may not be used as the earth. It is also better IMO to draw a separate earth as some fittings where you terminate your earth would have conductors running to earth other metal parts of the fitting. Which would not then be earthed as only the one metal part would be in contact with the conduit earthing system say at the round box.

We also had it where people changed old sockets for new ones and the new sockets were plastic ones. They do not have the connection that runs from the screw holes too the earth like the UK sockets. So people would swap the sockets only see 2 wires connect those and not think to connect a tail to the back box to get an earth for the sockets.

just my confusing 2 pence

 

[Engineer54]

Re: Why is it important to have earth wire run as bare, than insulated in a metal con

I would say all my conduit work I have done,has all called for cpc (spec required).

Sounds like the spec's for your projects have all been produced by kids that know no better. It's a completely pointless exercise to pull in a CPC into a metallic conduit containment system. You can make up every excuse you can possibly think of, and it will still NOT be necessary to run a CPC in to a new and/or continuous metal conduit containment!!


Our building installations are around 80/85% metal conduit and trunking, and not a single separate insulated or otherwise CPC is to be seen anywhere, in any of those systems...