Tails query.

[securespark]

Would you upgrade the 16mm² tails on an installation if you were adding a spur to the ring?

Are you breaking the regs if you don't?

Assume you don't know what the cut-out fuse size is.

If the CU had undersized earth terminals, how would you fit a 16mm² earth?

A bit cryptic, but bear with me...

 

[JohnD]

undersized earth terminals...

I presume this is on a rather old CU with room for only 10mm (or even 6mm?) earth (old ones usually had bigger holes at the ends of the bar)
AFAIK, the usual bodge is to divide the strands into two prongs, like a pickle-fork, and put one prong in each of two holes.

In some cases (another bodge ) e.g. old Wylex Standards, where the earth bar may be retained by machine screws that pass through the enclosure from the outside, it is possible to use a longer bolt with a nut, and retain an earth block on the outside of the casing. This is also an easy fix on a metalclad CU.

p.s. thinking about the earth-bar fixing screws on old Standards, I am not at all sure that they add up to 16mm. Maybe we ought to have drilled them out and used bigger screws. Or unshipped the old bar and put a bigger one in. Or something.

 

[RF Lighting]

Personaly if it were me, I would fit the spur but note down on the EIC / MEW cert that the existing installation was NTCS

I would upgrade the tails & main earth if a CU swap was called for.

 

[securespark]

Thanks guys.

Just one point. If you can't access the main fuse, there's no saying it isn't a 60A. In that case, 16/10 for the tails would be OK??

 

[JohnD]

but there's also no saying it isn't 80A or 100A, if that's what it says on the holder (It often does but it often isn't true).

 

[luminaire]

Why take the risk, why not suggest upgrading CU, tails and earth?
It's got to be better and safer in the long run for the client.

 

[JohnD]

You mean, why not turn a simple and cheap job (fitting a spur) into.....?

 

[Adam_151]

If you upgrade the tails, chances are you'll now have 16mm tails from head to the meter and 25mm from meter to the board, if you ask the DNO then 9 time out of ten they'll say that their 16mm tails are adequate (and indeed their 16mm service cable), but its all magically safer now because it complies to BS7671 to the letter now!

For a a spur socket I can't see what the problem is with noting it, for a shower it'd probably be different...

 

[securespark]

Ok. A spur we had installed was queried by an NIC spark because he had connected it to the origin of a 15A radial with one fused spur on it with nothing connected to that spur.

He also hadn't upgraded tails.

I agreed to upgrade earth tail & NTCS the others, but NIC spark said our spur was a new circuit and should have an EIC. I argued it was an extension of the radial fed from the origin as per OSG.

In the end I contacted NIC Tech who said that as the original circuit was not to table 8A in OSG, we could not extend it.

Opinions, please guys!!

 

[Spark123]

It depends how you look at it, it is a fundamental requirement of BS7671 that before any alteration or addition is carried out that it shall be ascerned that the existing equipment, including that of the distributer which will need to carry existing load is adequate, also earthing and bonding arrangements are adequate.

 

[securespark]

Fair enough about the earth, but what do you think about the radial malarky?

 

[Adam_151]

Its an extension of a circuit that already exists without massive changes to how it is (like a ring added to the end of an old cooker circuit would be), I'd say that a MWC was appropiate

And not being a standard circuit doesn't perclude anything, just means you have to satisfy yourself that it meets BS7671, with a 15A radial you can justify it on the back of the 20A radial as long as it meets conditions for that and the load is sure to be no more than 15A (a single socket and boiler FCU meets this in my eye)

(though I'm not a massive fan of 'branched radials' as they complicate testing a little)

 

[securespark]

Not if both feeds are present at the board...

Just feel the NIC are being excessively sniffy here - and they promised me they only work to 7671 "just like you do".

Oui, d'accord. Donnez-moi un seau....