MICC cable and sockets

[timhoward]

Bit of advice please. Not too used to this stuff.
In large old building, a couple of MICC radial circuits feeding a few sockets each. All tests pass, all RCD protected, very good Zs etc.
Questions:

• chassis of metal consumer unit being used for CPC, no banjos/fly leads etc. It clearly works very well but should there be a banjo / pyro clamp really?
• all 12 sockets have no earth fly lead from metal surface box to front. Again metal box used for cpc. So cpc to socket relies on case making good connection and the 2 screws. Easily solved of course.

My initial hunch is C3 for 1st one as it would require effort to make it dangerous and C2 for 2nd one.
Thanks.

 

[telectrix]

agree.

 

[7029 dave]

No banjo's were used on Micc because of the the copper to metal, however fly leads should be fitted from back box to sockets.

 

[Julie.]

My views:

• chassis of metal consumer unit being used for CPC, no banjos/fly leads etc. It clearly works very well but should there be a banjo / pyro clamp really?

No code - continuity is achieved, unlikely to end up loosing it to rust etc, adding an additional earth connection either by changing to tailed pots, or banjos could be done of course.

• all 12 sockets have no earth fly lead from metal surface box to front. Again metal box used for cpc. So cpc to socket relies on case making good connection and the 2 screws. Easily solved of course.

I would C3 - the first part is the same as above, but depending on location could be more susceptible to rust, so in some cases a banjo or change to a tailed pot would be better; if the location doesn't lead to this then no code again. The second part is still C3 for me, there is continuity to the socket CPC under normal or fault conditions, it would only be not connected if the socket was removed - which should not be normal operation.

 

[7029 dave]

I very rarely used tailed pots, only on jobs that specified it, looked like a sting ray, they were so solid didnt like them.

 

[timhoward]

Thanks all. I think I've terminated about 12 of these in my life so won't be changing pots!

 

[Timbo]

Thanks all. I think I've terminated about 12 of these in my life so won't be changing pots!

And if they are imperial MI's you might have issues.
Fit flyleads and let sleeping dogs lie.