Pyro Cable

[shawl01]

Hi all,

I have been asked to look at a job of fitting a new CU in a small office block, no problem i thought!

When I went to assess the job the current wiring is split over 4 * 8 way fused CU's and everything is wired in 2 core PYRO not a bit of twin and earth anywhere (I am guessing because of age). Anyway customer wants to replace all 4 CU's for a new single CU

my questions are:
1) Are you still allowed to use PYRO today (We didn't cover this on my recent training, t&e yes, swa yes, but not pyro unless it's called something else in the 7671) ?
2) Is re-terminating it in a new CU bitch of a job ?

and a slightly aside question
3) When fitting a new CU, if the existing circuits don't meet 17th standards (eg. light circuit missing earths at fittings because they were clipped back) can you detail as an exception in your certificate (obviously ensuring all earth bonding is in place) ?

Many thanks to you all in advance.

 

[flameport]

1) Are you still allowed to use PYRO today (We didn't cover this on my recent training, t&e yes, swa yes, but not pyro unless it's called something else in the 7671) ?

Yes, you can still use it and you can still buy it.

2) Is re-terminating it in a new CU **** of a job ?

With the correct tools and someone who knows how to use them it is not too difficult. However if it is old, it may not be a metric size which will be a serious problem when you need to buy new pots etc.

3) When fitting a new CU, if the existing circuits don't meet 17th standards (eg. light circuit missing earths at fittings because they were clipped back) can you detail as an exception in your certificate (obviously ensuring all earth bonding is in place) ?

Possibly. Not going to happen with pyro though.

 

[shawl01]

Hi Flameport

Possibly. Not going to happen with pyro though.

Can you upack that one a bit more for me?

Many Thanks

 

[RF Lighting]

1) Are you still allowed to use PYRO today (We didn't cover this on my recent training, t&e yes, swa yes, but not pyro unless it's called something else in the 7671) ?

Yes you certainly are. Some jobs will not allow you to use anything else. (Pyro is my very favorite cable by the way)

It is referred to in BS7671 as Mineral Insulated cable.

2) Is re-terminating it in a new CU **** of a job ?

If you can avoid re-potting the cables then no. If you need to re pot any of the cables, and you have never done it before, you will struggle.

You need special tools, and it is quite a lengthy process which takes practice to get it right.

3) When fitting a new CU, if the existing circuits don't meet 17th standards (eg. light circuit missing earths at fittings because they were clipped back) can you detail as an exception in your certificate (obviously ensuring all earth bonding is in place) ?

If the fittinds are double insulated, then you could detail it on your certificate, and recomment to your client that it is rectified.

If the fittings are class 1, you should leave them disconnected.

You do know that on older pyro installations that fittings / boxes will be earthed by the cable sheath / gland assembly, rather than a seperate earth wire?

Have you done an IR test on the pyro before agreeing to the CU change?

At least you don't need to RCD the lighting circuits

Many thanks to you all in advance.

You're welcome.

 

[flameport]

You can't cut the earth off with pyro, as the earth is the outer copper sheath of the cable.

 

[shawl01]

At least you don't need to RCD the lighting circuits

lmao

Thanks

 

[electronicsuk]

One way to avoid too much reworking of the cable might be to gland everything into earthed steel trunking. You can then crimp and extend in singles and run the trunking all the way to wherever the new dis board is to be located.

 

[Wooshzz99]

Please dont take this the wrong way but you are WAY out of your depth with this.

This old pyro needs a lot of attention and it takes a lot of skill to remove the old pot seal and olive clean and re fit as previously said old imperial ends are not available and the new metric ones dont fit the cable.

My advice to you is to leave it alone.

If I was doing it I would use steel trunking or large metal adaptable boxes and terminate unto these. Most times people did not use red and black sleeving but taped the phase indications on the cables these usally come loose and then you will have to test polarity again this is a pita.

Hope this helps

 

[Spark123]

You could cheat by leaving the old CU in place and using it as a through box. Bit rough but wouldn't be the first time I have done it.

 

[Lectrician]

Pyro, offices..........And I bet you where going to install a '17th edition' CU