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Discuss Does this setup contravene any regs or is it ok? in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

Wes1000

Regular EF Member
I’ve just done a large job where I fitted a double stack board (23 ways) and by the time I’d finished we only had two spare ways left in the board. So I thought that I’d free up one more by moving the lighting circuit for the loft on to the lobby lighting circuit at the CCU so both circuits are now on the one 6A MCB. Other than that they are totally separate. They also only contain one light for the loft and two lights for the lobby (all LED’s)

To me this is no different from taking the supply from the last lobby light to the loft and actually might make it easier to find a fault if you could separate it at the board rather than mess about behind down lights.

All was good until I decided to use this job for my Stroma visit.....
I was told that in no way can I do this and I need to correct it or it will go down as a non conformity. After arguing the point for 10 minuets I gave in and put the other MCB in and moved the loft light on to its own circuit and all was peaceful again.

Who’s right here?
 

123

Electrician's Arms
Given it's a Stroma visit, I assume it's domestic?
I'd have left it as it was with 2 spare ways. But I don't see an issue with what you did?

Did they give you a reason as to why?
 

Wes1000

Regular EF Member
Yes it’s a domestic, new installation in a building conversion.

He just said the regs state every circuit has to be contested to a separate breaker. Now that is true re; reg no. 314.4 but my argument was that as soon as I connected the two together this becomes a single circuit. This is how I read the definition of circuit on page 28 in the definition section of the regs.

I don’t have a problem with moving it back, apart from I was told I was wrong to combine it.

I hate it when I’m wrong and the less it happens the better!
 

spinlondon

Forum Mentor
Yes every circuit must be connected to a separate way in a DB.
TEs the definition of a circuit is an assemble of electrical equipment supplied from the same origin and protected against overcurrent by the same device or devices.
If I were going to knock the design back, I would choose dividing the installation into circuits to avoid danger and minimise inconvenience in the event of a fault, and facilitating safe inspection, testing and maintenance.
 
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essex

Forum Mentor
He is correct and has backed it up with a Reg number.

How would you record Zs etc on the cert with two finals coming from one MCB?
 

SparkyChick

Making a banana smoothy for my fave gorilla
Staff member
Moderator
So how is this any different from say connecting a spur to a ring final from the MCB? Or installing say some hardwired smokes and taking a supply cable from a lighting MCB?

You're not wrong, the assessor is just being a super picky d1ck!

One, two, three, four cables leaving an MCB... it's not the cables that define what a particular circuit is, it's the MCB labelling. If it says Lobby and Attic Lighting, and it has one cable going up to the attic and one to the lobby, then whats the problem?

How would you record the Zs... you'd do what you do for any other circuit... test at each point and record the highest value.
 
L

LankyWill

He is correct and has backed it up with a Reg number.

How would you record Zs etc on the cert with two finals coming from one MCB?
Record the highest and make sure the other falls within values, it’s just common sense.
 
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Murdoch

Electrician's Arms
It sounds like westward10 was your assessor,,,,, he’s wrong.
 

SparkyChick

Making a banana smoothy for my fave gorilla
Staff member
Moderator
Poor practice. There are two circuits and the results should be recorded seperatly.
As @spinlondon pointed out, the definition of circuit is:-

"An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s)"

To list this as a non-conformity in a scheme assessment is wrong because it does not breach any regulations, which is the question the OP was asking.

Fundamentally I agree, it's not good practice to be doing it, but that doesn't alter the fact that it's not a breach of the regs.
 

Murdoch

Electrician's Arms
BYB Definitions

Circuit. An assembly of electrical equipment supplied from the same origin and protected against over current by the same protective device(s)

314.4 Where an installation comprises of more than 1 final circuit, each final circuit shall be connected to a separate way in the distribution board ....

Neither of these state that a final circuit only has 1 cable

so............ I would say that the OP's original circuit complied 100%

Or the OP could have whipped out a short length of T&E, plus some Wago's and joined the 2 cables just before the MCB and then what
 

Murdoch

Electrician's Arms
Wonder what the assessor would have made of a RFC, with a spur from the CU then ??
 

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