What code for this?

HappyHippyDad · Jun 16, 2021

Another what code!

This is in conjunction with an EICR I have just carried out.

9.5kW shower on 6mm and 32A MCB. Been in place for a long time, no signs of thermal damage in CU or 45A shower pull switch. Ref method C (where visible in loft), unable to clarify ref method where it is buried in walls, but no conduit visible. My thoughts.... No code, but I am unsure of the effect of 41A going through a 32A MCB over a long period of time? Will this eventually damage the MCB or have some other effect on it that may compromise it's ability to work as it should, and if so, is this a very unlikely occurrence that doesn't really need to be considered or the opposite?

No 30mA RCD on cable <50mm in walls (for 3 x circuits... cooker, water heater, lights).
No 30mA RCD for circuits running through/in special location
Main bonding in place, nothing to supplementary bond.
My thoughts.. I have always put C3. I still think C3, but I am starting to err towards C2 in general for no RCD. This is for 2 reasons, RCD's are now required for pretty much everything (and they save lives), secondly, does anyone know what the NAPIT codebreakers says about no RCD protection? I believe they say C2?

Cheers all.

timhoward · Jun 16, 2021

My take - for the shower the 32A breaker probably protects the 6mm T+E cable adequately, and there's a higher fixed load on the end that for a long time has proved not to cause tripping with no signs of thermal damage. So the first one isn't a biggie for me. No code, or C3 for new cable ideally required. MCB's are generally fairly resilient and you've checked the isolator too.

Regarding RCD protection - are any of the sockets likely or available to be used outside?
If not, you could construct a BPG4 argument that they are C3's.
You could construct a Codebreakers argument they are C2's:

You could also construct an "I'm the inspector and it's about time this rental had at least one RCD" argument too if you so chose, I'd normally chat with the landlord and see how reasonable they are - I prefer it to be mutually agreed than just code it C2 as it isn't potentially dangerous in a clear cut way.
I'm assuming it's a rental - might not be!

i=p/u · Jun 16, 2021

Put a 40A mcb on it , normally good if distance under 10M.. 6mm good for 47A. If you clamp the shower will probably ready 35 to 38A at most.

HappyHippyDad · Jun 16, 2021

timhoward said:
My take - for the shower the 32A breaker probably protects the 6mm T+E cable adequately, and there's a higher fixed load on the end that for a long time has proved not to cause tripping with no signs of thermal damage. So the first one isn't a biggie for me. No code, or C3 for new cable ideally required. MCB's are generally fairly resilient and you've checked the isolator too.

Regarding RCD protection - are any of the sockets likely or available to be used outside?
If not, you could construct a BPG4 argument that they are C3's.
You could construct a Codebreakers argument they are C2's:
View attachment 86772
You could also construct an "I'm the inspector and it's about time this rental had at least one RCD" argument too if you so chose, I'd normally chat with the landlord and see how reasonable they are - I prefer it to be mutually agreed than just code it C2 as it isn't potentially dangerous in a clear cut way.
I'm assuming it's a rental - might not be!

Cheers Tim.
Have you got the NAPIT code breakers book? Just wondering where you got the picture from? I'm guessing you have to pay, even if a NAPIT member, or is there a cheeky link somewhere.

timhoward · Jun 16, 2021

HappyHippyDad said:
Cheers Tim.
Have you got the NAPIT code breakers book? Just wondering where you got the picture from? I'm guessing you have to pay, even if a NAPIT member, or is there a cheeky link somewhere.

Hi
No, as a NAPIT member I probably shouldn't admit that I don't have it! I prefer to work to BPG4 in all honesty.
That picture came from a NAPIT article I received.
Codebreakers is about £20 btw.
Tim

Strima · Jun 16, 2021

No RCD but supp bonding in place I would C3.

I would C3 the shower size as there's no sign of thermal damage etc, and I would strongly recommend to the customer that it is either replaced or the MCB and cable replaced. Long term the MCB will start to either nuisance trip or even worse fail to operate when needed.

telectrix · Jun 16, 2021

up the MCB to 40A on shower. otherwise a C3. you can't tell if that 32A has been stressed running at (>) max. rated

HappyHippyDad · Jun 16, 2021

Strima said:
No RCD but supp bonding in place I would C3.

I would C3 the shower size as there's no sign of thermal damage etc, and I would strongly recommend to the customer that it is either replaced or the MCB and cable replaced. Long term the MCB will start to either nuisance trip or even worse fail to operate when needed.

Both options for the shower would result in it being safe, but both would be pretty expensive. Perhaps a better option would be to 'FI' it? Actually take a floorboard up, see where it goes up the first floor wall to the loft and take a bit out of the wall to see how it is routed. A bit messy, but probably cheaper than changing the shower or cable, as it's likely it'll end up as ref method C.

Pretty Mouth · Jun 16, 2021

HappyHippyDad said:
Another what code!

This is in conjunction with an EICR I have just carried out.

9.5kW shower on 6mm and 32A MCB. Been in place for a long time, no signs of thermal damage in CU or 45A shower pull switch. Ref method C (where visible in loft), unable to clarify ref method where it is buried in walls, but no conduit visible. My thoughts.... No code, but I am unsure of the effect of 41A going through a 32A MCB over a long period of time? Will this eventually damage the MCB or have some other effect on it that may compromise it's ability to work as it should, and if so, is this a very unlikely occurrence that doesn't really need to be considered or the opposite?

No 30mA RCD on cable <50mm in walls (for 3 x circuits... cooker, water heater, lights).
No 30mA RCD for circuits running through/in special location
Main bonding in place, nothing to supplementary bond.
My thoughts.. I have always put C3. I still think C3, but I am starting to err towards C2 in general for no RCD. This is for 2 reasons, RCD's are now required for pretty much everything (and they save lives), secondly, does anyone know what the NAPIT codebreakers says about no RCD protection? I believe they say C2?

Cheers all.

@HappyHippyDad , have a read of this similar thread I posted a while back, there is some input from the manufacturers there too which is interesting:

Coding question - 8.5kw shower, B32 - in - Electrical Testing & PAT Testing Forum

, Coding question - 8.5kw shower, B32, Electrical Testing & PAT Testing Forum, ElectriciansForums.net Est.2006 | Free Electrical Advice Forum and page_number.

www.electriciansforums.net

FWIW, I recon I see this arrangement (6mm/32A MCB, with shower pulling >32A) more often that I see correctly installed shower circuits. I have yet to find it having obviously damaged the MCB, and have only come across it causing nuisance tripping once (old 30A plug-in BS3871, 8.5kW shower IIRC). I usually award it a C3.

For a shower without RCD protection I give a C2, regardless of sup bonding. Shower manufacturers always state that they need RCD, and I am led to believe that has been the case for quite a while now (>15 years).