EICR RCD 63A exceeded by breaker total code

[bill01803]

As per title, what code do you think is applicable when a 63A RCD has a 40, 32, 6 & 20A breakers?
And gas not bonded but was required at time of building (2012) although not now?

 

[pc1966]

What is the main fuse?

What do you mean by "required at time of building (2012) although not now", has the gas pipe been replaced by a non-conductive one since then?

 

[bill01803]

It is probably an 80A but it say 100A on the carrier

 

[Ian1981]

An upfront ocpd of the rcd should be equal to or less than the current rating of the rcd, if the combined mcb’s downstream of the rcd have the potential to exceed the ccc of the rcd, then it should be coded on an EICR .
Diversity of the final circuits alone is no longer acceptable for providing overload protection of an rcd.
This is also applicable to main switch disconnectors to BSEN 60947-3

The gas service requires bonding if it meets the definition of an extraneous conductive part , regardless of any year.

 

[bill01803]

An upfront ocpd of the rcd should be equal to or less than the current rating of the rcd, if the combined mcb’s downstream of the rcd have the potential to exceed the ccc of the rcd, then it should be coded on an EICR .
Diversity of the final circuits alone is no longer acceptable for providing overload protection of an rcd.
This is also applicable to main switch disconnectors to BSEN 60947-3

But was this applicable in 2012?

 

[pc1966]

But was this applicable in 2012?

It does not matter, what matters is the question "is there a real risk?"

 

[pc1966]

I would suggest if it has been like that for a long time and there are no signs of thermal stress at all, then C3 as improvement.

But if there is any discolouration or evidence the RCD has been overheating due to it then C2.

 

[andyb]

If a 63a rated RCD gets a C3, then a lot , if not most, new populated boards supplied now would warrant a C3 the minute they are fitted.

I would say that if a board comes with 2 x 632 RCDs then that is as manufactured and attracts no code whatsoever. The 63a refers to the current that it can interrupt without being damaged, if it trips with say 100a flowing through it, it will more than likely get damaged and have to be replaced. But it would have done its job.

Thermal damage to any components in a CU, not just RCDs would require at least C2, so that’s not really relevant.

 

[Ian1981]

If a 63a rated RCD gets a C3, then a lot , if not most, new populated boards supplied now would warrant a C3 the minute they are fitted.

I would say that if a board comes with 2 x 632 RCDs then that is as manufactured and attracts no code whatsoever. The 63a refers to the current that it can interrupt without being damaged, if it trips with say 100a flowing through it, it will more than likely get damaged and have to be replaced. But it would have done its job.

Thermal damage to any components in a CU, not just RCDs would require at least C2, so that’s not really relevant.

That’s the point, a 63 amp rcd won’t trip if it gets 100amps pulled through it, you could wack 1000 amps through it and it will just melt rather than trip.
I suspect the reason this regulation changed is all the burnt out 63 amp rcd’s having 8plus circuits hanging off them.
It has No overload protection other than the upfront protection device.
A C3 at most without evidence of thermal damage in my opinion.

 

[andyb]

That’s the point, a 63 amp rcd won’t trip if it gets 100amps pulled through it, you could wack 1000 amps through it and it will just melt rather than trip.
I suspect the reason this regulation changed is all the burnt out 63 amp rcd’s having 8plus circuits hanging off them.
It has No overload protection other than the upfront protection device.
A C3 at most without evidence of thermal damage in my opinion.

You may well be right Ian, but my point is that if you purchase and fit a new populated board such as below, you would need to put down the RCDs as a departure from the reg's. I would say that they were manufactured to a BS and fitted as per manufacturer's instructions.

 

[westward10]

If a 63a rated RCD gets a C3, then a lot , if not most, new populated boards supplied now would warrant a C3 the minute they are fitted.

I would say that if a board comes with 2 x 632 RCDs then that is as manufactured and attracts no code whatsoever. The 63a refers to the current that it can interrupt without being damaged, if it trips with say 100a flowing through it, it will more than likely get damaged and have to be replaced. But it would have done its job.

Thermal damage to any components in a CU, not just RCDs would require at least C2, so that’s not really relevant.

63A relates to it's continuous running duty in normal operation. It's breaking capacity will be considerably higher into KAs so switching a 100A load is not likely to cause any damage.

 

[loz2754]

You may well be right Ian, but my point is that if you purchase and fit a new populated board such as below, you would need to put down the RCDs as a departure from the reg's. I would say that they were manufactured to a BS and fitted as per manufacturer's instructions.
View attachment 64824
View attachment 64825

Not really. You would be able to purchase and install this board if the design of the installation permitted it to be installed in line with the said requirements for overcurrent protection of the RCDs.
Otherwise you would have to specify a different board for that particular installation.

 

[andyb]

63A relates to it's continuous running duty in normal operation. It's breaking capacity will be considerably higher into KAs so switching a 100A load is not likely to cause any damage.

Thanks for that clarification Westward, I suppose that a board with a 100a main switch and 2 x RCDs is designed for a fairly balanced load over the two RCDs. I don't think I'll be coding this anytime soon unless I think one of the RCDs is likely to have more than 63a running through it by design. I've never come across this, most of the domestic installations I test don't even have 50a as maximum demand.

 

[Ian1981]

I don’t think it is a departure from bs7671 as how are you achieving the same level as safety, it would be a blatant non compliance.

 

[andyb]

Not really. You would be able to purchase and install this board if the design of the installation permitted it to be installed in line with the said requirements for overcurrent protection of the RCDs.
Otherwise you would have to specify a different board for that particular installation.

True Loz but the OP was just adding up the ratings of the MCBs and the boards illustrated both come with MCBs totalling near or over 200a. So it would be impossible to satisfy the regs as being described here.

I take peoples point here but on PIRs I'll still use my judgement to determine whether I think it's okay for a particular installation.