Discuss AC RCD’s C2? Absolutely! in the UK Electrical Forum area at ElectriciansForums.net
The AC RCD is essentially rendered useless due to DC current. So off the top of my head circuits within a bathroom, sockets supplying external equipment, electric showers, cables in walls less than 50mm from the surface…all require RCD protection in a standard home, however if the RCD doesn’t work, how is that not potentially dangerous? I wouldn’t like to be the one justifying my case to the man in the wig over this one!You might be able to make such a case for specific installations, but as a blanket statement I'd imagine it would be dificult to back up.
How would you justify coding every Type AC RCD as "Potentially dangerou’. Urgent
remedial action required"?
What potential danger exists in the average home with Type AC protection?
The AC RCD is essentially rendered useless due to DC current. So off the top of my head circuits within a bathroom, sockets supplying external equipment, electric showers, cables in walls less than 50mm from the surface…all require RCD protection in a standard home, however if the RCD doesn’t work, how is that not potentially dangerous? I wouldn’t like to be the one justifying my case to the man in the wig over this one!
An RCD that won’t work due to DC current injected downstream! Apologies, I wouldn’t say a blanket C2 but certainly more common than not in my opinionCan you clarify if you mean an RCD that won't work as it has failed or an RCD that won't work due to DC current injected by a downstream appliance?
I may have grasped the wrong end of this particular stick, but in my defence your OP is open to misinterpretation and thread title suggests blanket C2 for Type AC protection.
An RCD that won’t work due to DC current injected downstream! Apologies, I wouldn’t say a blanket C2 but certainly more common than not in my opinion
If you read the Best Practice guide #4 for EICR coding (Nov 2022) from Electrical Safety FIrst, it states for "A Type AC RCD installed where a Type A RCD required" to be coded as C3.
Yes, that’s essentially my point. I’m seeing a lot of people pass over this issue with AC rcds and not even bother coding it. It’s a major issue that’s being ignored by too many!Wouldn't you generally code any RCD that failed to work, for any reason, as C2?
Yes, that’s essentially my point. I’m seeing a lot of people pass over this issue with AC rcds and not even bother coding it. It’s a major issue that’s being ignored by too many!
It also says that coding is entirely at the discretion of the inspector and the document is merely a guide. I would rather be fussy and improve a system than be lazy and have someone’s death on my conscience. Honest question, if you know an AC rcd may not work in a fault situation, explain why you would code it as a C3 and negate the need for someone to fix it. Imagine a child sticks their finger in a lamp holder? But the rcd fails…If you read the Best Practice guide #4 for EICR coding (Nov 2022) from Electrical Safety FIrst, it states for "A Type AC RCD installed where a Type A RCD required" to be coded as C3.
An AC rcd*Someone sticking their fingers into a lampholder may well not bother an RCD.
Any RCD.An AC rcd*
Sure…Any RCD.
It also says that coding is entirely at the discretion of the inspector and the document is merely a guide. I would rather be fussy and improve a system than be lazy and have someone’s death on my conscience. Honest question, if you know an AC rcd may not work in a fault situation, explain why you would code it as a C3 and negate the need for someone to fix it. Imagine a child sticks their finger in a lamp holder? But the rcd fails…
Sure what?Sure…
It’s common knowledge that DC current in a circuit with an AC RCD impairs it’s ability to work. Domestic properties have numerous electrical items, induction hobs, led lighting, EVCP’s that all can present this within an installation. There are loads of videos on YouTube explaining the logic behind it. It’s in the regs check out 531.3.3! As for sound judgement I’m an electrical technician with an electrical engineering degree and twenty years testing experience. I think I’m suitable to make the decision. There is a reason they are banned in half the world!A short while back we established that you were commenting on failed units, but now the conversation seems to have shifted to RCDs that 'may not work in a fault situation'.
How are you establishing that an RCD may fail to operate?
As for coding being at the discretion of the inspector, that's the sort of argument applied by testers who blanket code insulated CUs as C2.
Coding should be back up by regulations and sound engineering judgement. It should not be whimsical in nature.
It’s common knowledge that DC current in a circuit with an AC RCD impairs it’s ability to work. Domestic properties have numerous electrical items, induction hobs, led lighting, EVCP’s that all can present this within an installation. There are loads of videos on YouTube explaining the logic behind it. It’s in the regs check out 531.3.3! As for sound judgement I’m an electrical technician with an electrical engineering degree and twenty years testing experience. I think I’m suitable to make the decision. There is a reason they are banned in half the world!
Honest question, if you know an AC rcd may not work in a fault situation, explain why you would code it as a C3 and negate the need for someone to fix it.
Imagine a child sticks their finger in a lamp holder? But the rcd fails…
Indeed they do, but I must admit I find this suggestion somewhat questionable. Surely if an RCD is required, and the circumstances of the installation dictate that it needs to be a minimum of a Type A RCD because a Type AC RCD could be disabled by circulating DC currents then a C3 Observation seems overly lenient. But alas, you are correct that this is what that Best Practice Guide suggests.If you read the Best Practice guide #4 for EICR coding (Nov 2022) from Electrical Safety FIrst, it states for "A Type AC RCD installed where a Type A RCD required" to be coded as C3.
Common knowledge indeed, but one thing that remains mostly unanswered is how the DC current comes to be passing through the RCD in the first place? Presumably a circuit must be completed for it to flow, so is it deliberate, or is it due to faulty equipment? And what route does it take? Any answers (with sources) appreciatedIt’s common knowledge that DC current in a circuit with an AC RCD impairs it’s ability to work. Domestic properties have numerous electrical items, induction hobs, led lighting, EVCP’s that all can present this within an installation. There are loads of videos on YouTube explaining the logic behind it. It’s in the regs check out 531.3.3! As for sound judgement I’m an electrical technician with an electrical engineering degree and twenty years testing experience. I think I’m suitable to make the decision. There is a reason they are banned in half the world!
It has been changed because the older RCD technology is no longer appropriate in a modern installation.Another reg that I think is daft and has been changed for changes sake.
Tripping under test conditions is different to tripping under real world conditions.I would have thought that in 99% of situations an AC RCD will be just fine, certainly in all the EICR's that I've done over the last few years and all the installations that I've done with AC ones they all tripped off no problem under test
My house is a perfect example, I have lots of electonic goods, your typical house, probably more so with my computer stuff, yet the 10 year old RCD trips off every time the oven is on for more than 30 minutes, its needs a new element.
DC leakage occurs from electronic loads, especially switch mode power supplies and the like.Common knowledge indeed, but one thing that remains mostly unanswered is how the DC current comes to be passing through the RCD in the first place?
Presumably a circuit must be completed for it to flow, so is it deliberate, or is it due to faulty equipment? And what route does it take? Any answers (with sources) appreciated
Well if it has been affected by DC leakage then it still tripped so all is good and if it hasn't been affected by DC leakage then all is good too. My house has all the possible scenarios that could cause DC leakage but the RCD still trips merrily away.It has been changed because the older RCD technology is no longer appropriate in a modern installation.
Tripping under test conditions is different to tripping under real world conditions.
I think you've misunderstood some basics here.
The RCD tripping due to a faulty oven element does not prove whether or not it has been affected by any DC leakage.
Sorry on behalf of everyone else we didn’t realise you had a degree, I’ll be the first to bow down to you. Our years practical experience working on site years means nothing when the piece of paper enters the room.It’s common knowledge that DC current in a circuit with an AC RCD impairs its ability to work. Domestic properties have numerous electrical items, induction hobs, led lighting, EVCP’s that all can present this within an installation. There are loads of videos on YouTube explaining the logic behind it. It’s in the regs check out 531.3.3! As for sound judgement I’m an electrical technician with an electrical engineering degree and twenty years testing experience. I think I’m suitable to make the decision. There is a reason they are banned in half the world!
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