Coding questions

[timhoward]

Hi. This is a gloriously messy installation I looked at this morning at a house a friend just purchased. It t became quickly clear it was more economical to rewire than rectify. I will however be putting findings in writing and there are a couple of new situations for me. So here goes:

My initial guess for this unlabelled collective was RCD for shower, two lighting, re-wirable 30 amp for sub main to garage CU, 2 ring final and a cooker.
So at first I thought apart from insufficient RCD protection and being overdue a new CU (which solves the former) it was going to be mainly ok.


Unfortunately the shower is one of the plug in B32's, and the separate RCBO is the garage sub main.
How would you code:
1) no RCD protection for electric shower. (gut feeling is C2 but never had this before - thoughts welcome. I wouldn't want to use the shower myself, but it's not dangerous right now, it would be in fault conditions though. 701.411.3.3 is clear RE 18th requirement)

2) Various issues with sub-main distribution cct for garage, connected to B40 amp RCBO:
a) concealed joint in garage sub main circuit 'somewhere' (FI ?) It leaves main CU as 6mm T+E and enters garage CU as 2.5mm SWA from underground.
b) current carrying capacity insufficient for OCPD and inadequate earthing conductor size (C2 is gut feeling as short circuit or overload faults would be dangerous)
c) Earthing arrangements for garage CU inadequate as TN-C-S system at house, and only earth path at garage is currently 2.5mm SWA distribution circuit. No local electrode. Isolator is at least a 30ma RCD at garage. I'm thinking C3 as L to E fault covered by RCD (in fact RCD each end with no discrimination which is a further issue). NB Not loop tested yet and that may change view!

3) no RCD protection for sockets or luminaires (C3)
4) no RCD protection for 2 outside sockets, and a 16 amp outside socket. (C2 ?)

5) Lighting circuit, 1.5 T+E entering a 2G light switch, N and E choc blocked into two 0.75mm flexes, L to each flex L switched. Current carrying capacity insufficient for OCPD (C2 ?) [ One flex went to outside light. The other flex was not traced.]

6) The rewireable 30A fuse is in fact a circuit in 4mm T+E feeing a double socket in utility room (no rcd - C3) and this delight below which I'd assume there isn't much disagreement about (C1) and I've already disconnected it.





There were many many more as whoever previously owned this house had no fear and wasn't afraid of joining anything to anything but the main questions are above.
Thanks a lot.

 

[bill01803]

If there is supplementary bonding in the bathroom the shower would be ok without rcd in the 16th and previous unless it is TT

 

[timhoward]

If there is supplementary bonding in the bathroom the shower would be ok without rcd in the 16th and previous unless it is TT

Thanks for this. No supplementary bonding in this case.
In a nutshell remaining questions are:
1 - shower with no RCD and no supplementary bonding. I still think C2 as previous regs would have required bonding.
2 - Outside sockets with no RCD?

 

[JBW175]

Thanks for this. No supplementary bonding in this case.
In a nutshell remaining questions are:
1 - shower with no RCD and no supplementary bonding. I still think C2 as previous regs would have required bonding.
2 - Outside sockets with no RCD?

C2's for both of them for me

 

[Taylortwocities]

the separate RCBO is the garage sub main.

Sorry, can’t readily see an RCBO in the picture. Which one is this?
Maybe the quality of the picture…

 

[timhoward]

Sorry, can’t readily see an RCBO in the picture. Which one is this?
Maybe the quality of the picture…

Yeah - not best photo and I didn't describe well. I was referring to this MCB/RCD. It serves the garage distribution circuit.

 

[Taylortwocities]

Thanks. It looked just like an RCD in the photo.
I see so many “garage” circuits protected by a 40A RCD, the installing muppet thinking the 40A refers to some current limiting function.

but yes, that is indeed an RCBO (they don’t make them like that any more!)

 

[timhoward]

I see so many “garage” circuits protected by a 40A RCD, the installing muppet thinking the 40A refers to some current limiting function.

Yes, seen this before too - a pertinent reminder to look twice and not assume that something actually is what it obviously should be...!