Just had an EICR done for the first time on my flat, built 2001. The circuits are fine but I was surprised to learn there’s no RCD. Naturally I want one installed regardless of the need to pass the EICR, but the electrician is saying it’s necessary to replace the whole consumer unit (pictured). Can this relatively modern unit really not accept RCDs?
Told I have to replace this relatively modern Consumer Unit
MK changed the design maybe twice since that one, they now no longer make any consumer units, so any parts if ever made would be second hand
You have an RCBO (MCB with built in RCD) controlling the shower circuit.
Now if you can get a dozen of these of the right amperage...
The best thing you can do is change the whole board for a metal one with all RCBOs.
Unfortunately things that seem not all that old, and quite modern, are rapidly becoming very outdated now.
Sad but true.
Now if you can get a dozen of these of the right amperage...
The best thing you can do is change the whole board for a metal one with all RCBOs.
Unfortunately things that seem not all that old, and quite modern, are rapidly becoming very outdated now.
Sad but true.
It's not so much that it "can't accept RCDs" it's that there are a few other problems, which sadly make a consumer unit replacement the most sensible remediation.
The first problem is that manufacturers sometimes do a poor job of maintaining support/compatibility over time. I'm not sure if modern MK stuff is compatible with MK stuff of that board's era. I was under the impression that while the precise designs had changed they were still compatible but I may be wrong.
The second problem, is a lack of space. Having a single RCD for the whole house is not considered a good idea. What is consided the "minimum" these days is a "dual RCD split", where the circuits are split across two RCDs, but that needs more space in the board. Surge protection is also recommended nowadays though not absolutely mandatory. The other options in RCBOs, which provide RCD protection for each individual circuit, it may be possible to fit RCBOs, but by the time you have replaced all the MCBs with RCBOs you aren't far off replacing the whole unit.
The third problem is if you want to be fully compliant with current regs, the consumer unit needs to be made of non-combustible material, yours is not.
The first problem is that manufacturers sometimes do a poor job of maintaining support/compatibility over time. I'm not sure if modern MK stuff is compatible with MK stuff of that board's era. I was under the impression that while the precise designs had changed they were still compatible but I may be wrong.
The second problem, is a lack of space. Having a single RCD for the whole house is not considered a good idea. What is consided the "minimum" these days is a "dual RCD split", where the circuits are split across two RCDs, but that needs more space in the board. Surge protection is also recommended nowadays though not absolutely mandatory. The other options in RCBOs, which provide RCD protection for each individual circuit, it may be possible to fit RCBOs, but by the time you have replaced all the MCBs with RCBOs you aren't far off replacing the whole unit.
The third problem is if you want to be fully compliant with current regs, the consumer unit needs to be made of non-combustible material, yours is not.
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It's not necessary to replace the consumer unit, but it certainly makes the most sense. It's unlikely to be feasible to do much more than replace all the MCBs for RCBOs, in which case you may as well replace for a consumer unit compliant with the latest version of BS7671
Current rating. Amperes is a unit not a quantity...
They've apparently recently redesigned the MK Sentry consumer units, but they certainly do make consumer units again.
Current rating. Amperes is a unit not a quantity...
They've apparently recently redesigned the MK Sentry consumer units, but they certainly do make consumer units again.
Thanks everyone, time to get a spanking new unit then. Electrician seemed a decent chap but great to get an independent opinion here.
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Sort of tickled me when my fairly new consumer unit needed to be replaced (obsolete bits and needed extra circuit) the plastic one which had replaced the old metal boxes now has to be metal again!
Plastic replaced the old conductive metal box, but the sparks said the plastic boxes were more of a fire risk so back to metal again! What goes around comes around.
Plastic replaced the old conductive metal box, but the sparks said the plastic boxes were more of a fire risk so back to metal again! What goes around comes around.
Sort-of, but the 'they' is not MK themselves -- MK-branded CUs and components thereof are apparently now being manufactured under licence and sold by CircPro (an "Authorized Licensee" , owned by the Yihua Holding Group).
Kind Regards, John
It was not sparks but, rather, the London Fire Brigade who came up with this seemingly rather half-baked idea.... the plastic one which had replaced the old metal boxes now has to be metal again!
Plastic replaced the old conductive metal box, but the sparks said the plastic boxes were more of a fire risk so back to metal again! What goes around comes around.
As I often observe, it's probably only a matter of time (if it hasn't happened already) before there are deaths and/or serious injuries as a result of people fiddling around injudiciously in/around metal CUs.
Requiring CUs to be fairly 'fire resistant' is not unreasonable (although requiring them to be 'non-combustible' is clearly ridiculous) but, despite how manufactures have chosen to respond to this, that doesn't necessarily mean that they have to be 'conductive) metal. There are plenty of non-metallic materials (like the urea-formaldehyde resins used extensively for electrical accessories) which are pretty 'fire resistant'.
Furthermore, the regulation, as written is even more stupid since it includes no requirement for fire 'containment'. Provided only that what material there is qualifies as 'non-combustible', there can be as many ~12mm diameter holes in the front, sides and bottom as one wants!
Where electricity is involved, non-conductive materials are (or should be) our friend!!
Kind Regards, John
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Some MCB's the opening of the terminal did not force the terminal open, and it was easy to insert the MCB so the bus bar simply pressed against the terminal rather than being securely clamped, this could cause over heating which did cause some fires, but there was a knee jerk reaction by the London Fire Brigade which resulted in the introduction of metal consumer units.
I have seen a case where the terminals were simply never tightened up. The boss ordered a CU with a selection of MCB's and to assist carrying the unit the supplier had put the MCB's in the CU. Electrician fitted it without checking the torque on the screws, to be fair the instructions do say check all terminals, but normally a populated CU does have the terminals tight.
At under £20 each I would be considering simply renewing the MCB's for RCBO's, I would be wary, your existing RCBO says 7937s and new one says H7936s so I would remove the existing and take it with me to get replacements so I can ensure they will fit. They do not look identical
I have found 7937s at £22.19 each both are type AC and really today we should be fitting type A, but I have all type AC.
Maybe some one can tell us if they do interchange? And which one is latest version.
I have seen a case where the terminals were simply never tightened up. The boss ordered a CU with a selection of MCB's and to assist carrying the unit the supplier had put the MCB's in the CU. Electrician fitted it without checking the torque on the screws, to be fair the instructions do say check all terminals, but normally a populated CU does have the terminals tight.
TLC website said:
At under £20 each I would be considering simply renewing the MCB's for RCBO's, I would be wary, your existing RCBO says 7937s and new one says H7936s so I would remove the existing and take it with me to get replacements so I can ensure they will fit. They do not look identical
I have found 7937s at £22.19 each both are type AC and really today we should be fitting type A, but I have all type AC.
Maybe some one can tell us if they do interchange? And which one is latest version.
Several things wrong with that CU. Why is the boiler on a 32 amp MCB, 6 would be ample? Likewise I would expect the water heater to be on a 16 amp MCB not 32 and the alarm should be on a 6 amp not 16.
You could put the alarm and smokes on the lighting circuit and the boiler on a socket circuit which would give you 4 spaces including the one you already have. That is room for two RCDs.
You could put the alarm and smokes on the lighting circuit and the boiler on a socket circuit which would give you 4 spaces including the one you already have. That is room for two RCDs.
What you say corresponds to normal parctice but, if the cables concerned are up to those currents, there's nothing wrong with it - given that the MCBs exist to protect the cables, not to 'protect' (or 'limit') applied loads.
There's not much point in adding two RCCBs when you don't have corresponding neutral bars for them...
I'd have to disagree with @ericmark on replacing the circuit breakers with RCBOs on the existing DB. MK Sentry RCBOs are very expensive in comparison to other (better) makes - i.e. they are dearer even than Hager, certainly in my wholesalers. I had to replace three circuit breakers recently with RCBOs in an MK Sentry. Luckily they had stock of them. But they are also only Type AC, which shouldn't really be fitted in this enlightened day and age.
Deleting the MK Sentry DB and putting something good in (e.g. Hager) has to be where the smart money is.
You'd really have to ask them that.
One might suspect that (assuming it is 4mm), they did not 'put it in for (just) a boiler' but, rather, repurposed a circuit that previously had needed 4mm/32A OR (b) had reason think that the circuit might be subsequently repurposed for something other than 'just a boiler'.