Is "the era of dual-RCD CUs long gone" ?

[SUNRAY]

Cost is taken with cheap versions as if considering cost will not go for expensive. So Fusebox prices £17.16 for RCBO short, or £12.12 for type AC, £13.19 for type A long. And £119.40 for AFDD type. MCB is £2 and a RCD £19.76 for 63 amp and £25.22 for 100 amp both type A. So under 4 ways RCBO is cheaper. So only as we look at 5 way and over is there really any saving.

Even with 4 MCB's per RCD I have seen nuisance tripping, no faults found, we should check the back-ground leakage will all running is less than 9 mA, but near impossible to do with a new installation as no idea what will be plugged in.

To comply with regulations every installation shall be divided into circuits, as necessary, to take account of danger that may arise from the failure of a single circuit such as a lighting circuit, and reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation.

Not equipment not simply the fixed wiring, I know there was an argument the RCD did not form a circuit, but that is really clutching at straws, however increasing the number of RCD's is not going to necessary increase safety, the same argument which has been put forward for SPD goes for twin RCD it is up to the client to decide if he was to pay for part insurance against damage from surges, or tripping of the RCD, it is suggested the electrician gets a disclaimer signed when not fitting SPD the same applies for not fitting all RCBO, or fitting type A RCD's.



If the owner is asked to sign that, then in the main I can't seen RCD's being used. The real question is where the property is not occupied by the owner, if a landlord signs the above, would be then be libel for any claims over loss of food or injuries due to an RCD tripping. Would the landlord insurance cover him?

The only appliances I provide are cooker, heating and hot water ie: nothing portable. If any of those or the electrical installation are shown to have caused any loss then yes it is covered, including their food by My landlord insurance, it also covers emergency accomodation etc.

As to cost... a BG 2 RCD board from beloved SF fully populated with 10 MCB's currently selling for £57.59 or the smaller size with 6 MCB's costs £57.22 including 100A isolator and 63A RCD's. (Yes I know some will start bleating about compliance but many smaller properties still only have a 60A fuse, such as all 3 of my one bed flats on looped supplies) from the same stable a 9 way board with 100A isolator (7 spare slots and smallest unpopulated currently listed) is £24.99 and 2 RCBO's are £16.32 each, total £57.63 so break even at somewhere well under 2 circuits!
There are many, many, properties protected by only one RCD with no apparent problems and as John correctly says a tripping RCD is absolutely no different to a power outage.

I have never been aware of any genuine RCD false tripping, in each case I've encountered there has been a real cause. In Che Sunray the 2 RCD board started tripping overnight and changing to RCBO's on the affected side (only done as enough were 'in stock') soon confirmed the suspicion it was kitchen ring, excluding fridge/freezer, and further subdivision soon identified dishwasher. I swapped the mains filters between tumble drier and dishwasher and tripping moved with it. This was with the dishwasher turned off.

In one of my rentals the brand new washing machine was the culpret and another was the Sky box but both caused me unfunded time and effort. Yes I could have invoiced but I'm too soft for that.

 

[SUNRAY]

Cost is taken with cheap versions as if considering cost will not go for expensive. So Fusebox prices £17.16 for RCBO short, or £12.12 for type AC, £13.19 for type A long. And £119.40 for AFDD type. MCB is £2 and a RCD £19.76 for 63 amp and £25.22 for 100 amp both type A. So under 4 ways RCBO is cheaper. So only as we look at 5 way and over is there really any saving.

Even with 4 MCB's per RCD I have seen nuisance tripping, no faults found, we should check the back-ground leakage will all running is less than 9 mA, but near impossible to do with a new installation as no idea what will be plugged in.

To comply with regulations every installation shall be divided into circuits, as necessary, to take account of danger that may arise from the failure of a single circuit such as a lighting circuit, and reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation.

Not equipment not simply the fixed wiring, I know there was an argument the RCD did not form a circuit, but that is really clutching at straws, however increasing the number of RCD's is not going to necessary increase safety, the same argument which has been put forward for SPD goes for twin RCD it is up to the client to decide if he was to pay for part insurance against damage from surges, or tripping of the RCD, it is suggested the electrician gets a disclaimer signed when not fitting SPD the same applies for not fitting all RCBO, or fitting type A RCD's.



If the owner is asked to sign that, then in the main I can't seen RCD's being used. The real question is where the property is not occupied by the owner, if a landlord signs the above, would be then be libel for any claims over loss of food or injuries due to an RCD tripping. Would the landlord insurance cover him?

As a landlord the only appliances I provide are cooker, heating and hot water ie: nothing portable. If any of those or the electrical installation are shown to have caused any loss then yes it is covered, including their food by My landlord insurance, it also covers emergency accomodation etc.

As to cost... a BG 2 RCD board from beloved SF fully populated with 10 MCB's currently selling for £57.59 or the smaller size with 6 MCB's costs £57.22 including 100A isolator and 63A RCD's. (Yes I know some will start bleating about compliance but many smaller properties still only have a 60A fuse, such as all 3 of my one bed flats on looped supplies) from the same stable a 9 way board with 100A isolator (7 spare slots and smallest unpopulated currently listed) is £24.99 and 2 RCBO's are £16.32 each, total £57.63 so break even at somewhere well under 2 circuits!
There are many, many, properties protected by only one RCD with no apparent problems and as John correctly says a tripping RCD is absolutely no different to a power outage.

I have never been aware of any genuine RCD false tripping, in each case I've encountered there has been a real cause. In Che Sunray the 2 RCD board started tripping overnight and changing to RCBO's on the affected side (only done as enough were 'in stock') soon confirmed the suspicion it was kitchen ring, excluding fridge/freezer, and further subdivision soon identified dishwasher. I swapped the mains filters between tumble drier and dishwasher and tripping moved with it. This was with the dishwasher turned off.

In one of my rentals the brand new washing machine was the culpret and another was the Sky box but both caused me unfunded time and effort. Yes I could have invoiced but I'm too soft for that.

 

[JohnW2]

I would say SOME dual RCD boards are still being fitted, but not many - which may suggest the era of dual RCD boards has long gone. They are not as widely used as they were 13 or so years ago, which tells me the era is dead - even though people still fit them from time to time. ....I feel even though dual RCD boards are still made, and fitted from time to time, the era of dual RCD boards may be long gone, or at least becoming long gone, as I haven't noticed many people using them - because of relative cheapness and easieer fault finding. ... So, what am trying to say is that even though dual RCD boards are still made and sometimes installed ...

OK. I thought this was a fairly 'black and white' issue, but you're rather turning it into a semantic question - i.e. regarding the meaning of "the era is dead/'long gone', "not many", "not many people", "sometimes", "from time to time" etc.

For what it's worth, the last dual RCD board I fitted was about five years ago. And the last one that someone I know would have installed is around five years ago too.

Fair enough - if that's true, it's true. However, it appears that a lot of people must still be buying them and hence, I would have thought, installing them ...

... I've just looked at the TLC website. Of the many 'populated' CUs they offer, only two come with any RECBOs - an "all RCBO" one from Contactum and one with one RCD, 6 MCBs and 2 RCBOs from 'MK'. All the other 'populated' CUs (from BG, Contactum, Hager.'MK' and Wylex) come with 2 RCDs and multiple MCBs.

If "not many people" are installing dual-RCDs and even them only "from time to time", I cannot help but wonder what is happening to all these CUs being sold by TLC (and, although I haven't had time to look, probably most/all other wholesalers) - are they perhaps being used as door stops, or all sent to museums?

If people didn't believe dual RCD boards were still being installed, why would they vote no? And if they believed no one had installed them for several years, why is that any different to the previous sentence?

I've already said that, in either of those scenarios I would expect them to vote "yes" in both cases - but I really can't see how anyone could really believe either.

I don't want to annoy people by posting yet another poll, but if I were to post one asking:

• Do you believe that no-one has installed dual-RCDs for several years and that none are now being installed (Yes/No) ??

.... do you really think that anyone could honesty answer "Yes" to that question?? Even you have acknowledged that some ("not many") people continue to install them "from time to time".

So, what am trying to say is that even though dual RCD boards are still made and sometimes installed, the 'era' of dual RCD boards has gone - because I believe we are now in the 'era' of all-RCBO boards. ... Well we are, aren't we?

As I said, you've turned this into somewhat of a semantic discussion". If "we are now in the 'era' of all-RCBO boards" means "we are at a time when the use of all-RCBO boards is increasing", then I would have to agree with you. That would seem similar to saying, a decade or so ago, that we were "in the era of electronic vehicles" - but I doubt that many people back then would have paraphrased that as "the era of vehicles with internal combustion engines is long gone", would they?

Kind Regards, John

 

[ericmark]

I was surprised what a short time one has when a freezer fails, I was standing next to mine when it went bang, I had a spare freezer in the garage I used for brewing, so turned it on to allow it to cool first, an hour latter when I came to transfer the food, stuff at the top had already defrosted, stuff above the level of the rear panel which separates the coils from the main body.

I would assume it failed when it came to restart after the defrost cycle, and this has nothing to do with RCD's, except it shows how little time we have once the power fails, I have had a chest freezer seem to be OK after 8 hours without power, but the main point is seems, freezers today do show temperature when power was restored, removing the guess work, but in the main when a RCD has tripped be it with good cause or with no reason known for the trip, I have been able to reset it fast enough so food has not been spoilt.

But not every time, just before my move I lost two freezers full of food, and the worry is what may happen, not a report from insurers saying how many times a claim for lost food has been made. With a CU lasting around 25 years if not more, the question is what is the chance of a third or more RCD in the CU saving one freezer full of food in 25 years, and in the homes I have lived in the chance of a failure once for long enough to defrost food in 25 years I would say as around 90%, and it only needs it to happen once to pay the extra cost of having a third RCD.

To have a third RCD looking at less than £20, can't see how anyone's maths can show not worth the extra, even if only in peace of mind.

As to

the era is dead/'long gone

the era of Steam trains is also dead/long gone, but we still have them where I live.

RCD board from beloved SF fully populated with 10 MCB's currently selling for £57.59

That is cheaper than they have ever been, yes 63A RCD SF £12.25, but the 100 amp model is £23.74 so for the £57.79 we have a CU needing re-configuring to take a SPD and likely needs two replacement RCD's so add to the £57.79 2 x £23.74 plus £29.99. So real cost £135.26.

Yes see your point about 60 amp DNO fuses, but that raises another question, if fitted with a 60 amp fuse and it ruptures, will they replace it with a 60 amp fuse? I don't know the answer, this house also has 60 amp fuse, it did have a Wylex fuse box which had a 60 amp main isolator, which likely explains the 60 amp fuse. But should it rupture I think very likely it would be replaced with a larger fuse.

I was happy with my 14 way RCBO CU when we had a roof leak and some sockets got wet, I simply left the circuit tripped for a few months until repaired, had it been a twin RCD box I would have needed to have opened the CU and disconnected that ring final, not a big job for an electrician, but not so easy for the normal home owner.

The same with @SUNRAY tenants, he can respond fast and repair things, but any normal landlord would be panicking trying to find an electrician. OK claim off insurance, but the premiums will go up as a result, so not cost free.

So yes the era of two RCD's is gone, save for a few penny pinching landlords.

 

[SUNRAY]

yes 63A RCD SF £12.25, but the 100 amp model is £23.74 so for the £57.79 we have a CU needing re-configuring to take a SPD and likely needs two replacement RCD's so add to the £57.79 2 x £23.74 plus £29.99. So real cost £135.26.

Errrr

Surely one would not purchase a fully populated unit with the intention of replacing the most expensive bits in there.

And I see no point adding the totally useless junk for another £29.99.

 

[ericmark]

When one sees redundant stuff being sold very cheap, there is always a temptation to use redundant stock, we saw it when Wylex got out of the CU supply for a time, then sold off that part of business so up and running again.

I saw neighbours buy a car in same way, when the factory closed we got loads of cheap stuff, then the reverse as parts get rare.

I fitted two RCD's back in around 1992, one fed each of a pair of old Wylex fuse boxes, I still have spare RCD's 4 module wide, no marking as to if type AC, A, F, or B and seem to remember no electronics. There was no option back then, there was no such thing as a consumer unit, type testing had not come in, and no option to fit RCD's inside the fuse box.

As time progressed we had new products hit the market place which allowed us to fit RCD's in the distribution board, but it was limited by the configuration of the board, and even when single width RCBO's came out, they were longer and would not fit in the old boards, the old loadmaster board would take up to 70 amp MCB's and the isolator looked the same as a MCB except for the red bar, I know one guy who was fitting them thinking they were MCB's.

Future proof is impossible, but to fit stuff you know is being sold off as obsolete, unless used in temp stuff, is really not very cleaver, the problem is the electrician fitting it is unlikely to have the problem latter, it is the home owner who will have to foot the bill for a premature CU change.

I held on to old MCB, RCD, etc. And now I am faced with the going through loads of old stuff and binning it, people are slowly waking up to fact fitting obsolete stuff cost money in the long run.

I see it at work all the time, Bayer-Garratt is no longer trading, so anything which brakes has to be made from scratch, the cost of making one piston is huge. With electrical stuff can't see we have the option to make a replacement, if a dash pot motor starter fails, your unlikely to be able to make the parts to fix it, when did you last top up dash pots?

 

[SUNRAY]

When one sees redundant stuff being sold very cheap, there is always a temptation to use redundant stock, we saw it when Wylex got out of the CU supply for a time, then sold off that part of business so up and running again.

The Wylex I fitted recently theroetically falls into the temporary category in a commercial outbuilding although there are no plans for redevelopment, customer has a 4 drawer filing cabinet full of used switchgear to keep their elderly kit running with oodles of spares so although I wouldn't have proposed fitting one, it wasn't inappropriate to fit their property.

I fitted two RCD's back in around 1992, one fed each of a pair of old Wylex fuse boxes, I still have spare RCD's 4 module wide, no marking as to if type AC, A, F, or B and seem to remember no electronics. There was no option back then, there was no such thing as a consumer unit, type testing had not come in, and no option to fit RCD's inside the fuse box.

Winston will disagree with you and on this occassion I'll have to agree with him. Back in 1970's I recall a farm building with 3ph board with integral RCD main switch and MCB's (the tall type 1's shape) but of course in those days consumer units hadn't been invented, then they were called fuse box, fuse board, distibution board or any other name people wished to use.

As time progressed we had new products hit the market place which allowed us to fit RCD's in the distribution board, but it was limited by the configuration of the board, and even when single width RCBO's came out, they were longer and would not fit in the old boards, the old loadmaster board would take up to 70 amp MCB's and the isolator looked the same as a MCB except for the red bar, I know one guy who was fitting them thinking they were MCB's.

Again I's suggest these were available way back in 70's and configurable, albeit not with the ease of current CU's.

Back then RCD's & MCB's were very expensive and therefore not popular in domestic situations

In 1985 I built an extention to house my radio shack and fitted a secondhand steel Wylex (from a bootfair for £1) with integral 4 module width RCD as main switch so such things were freely available way back.
Here is one:
https://www.diynot.com/diy/media/untitled.15082/

 

[flameport]

Some people will install any old rubbish just because it happens to be available and is cheap.
Some manufacturers will create any old rubbish to supply that market.
Some retailers will continue to sell any old rubbish just because they can.

All of those are entirely different from installing consumer units which comply with BS7671.

 

[bernardgreen]

Some customers will buy any old rubbish because marketing say it is the "must have" item.

 

[SUNRAY]

Some customers will buy and install any rubbish because BS7671 says it'the current fashion/"must have" item.
Some manufacturers will create that rubbish to supply that market.
All of those are entirely different from installing units which safely fulfill the requirements of the job.

 

[JohnW2]

Some customers will buy and install any rubbish because BS7671 says it'the current fashion/"must have" item. ... Some manufacturers will create that rubbish to supply that market.

There will obviously be considerable variation in views as to what constitutes 'rubbish', but in terms of things for which the 'need' is controversial, I couldn't agree more.

Furthermore, as bernard has said, it is often marketeers, helped by views expressed in platforms such as this forum, which persuade the general public of their 'need' for something which is, at best, a 'controversial need'.

As I'm sure you will understand, it is because of my view that people ought to be given 'objective' information about the matters which we are discussing that I started this thread.

Kind Regards, John

 

[JohnW2]

But not every time, just before my move I lost two freezers full of food, and the worry is what may happen, not a report from insurers saying how many times a claim for lost food has been made. With a CU lasting around 25 years if not more, the question is what is the chance of a third or more RCD in the CU saving one freezer full of food in 25 years, and in the homes I have lived in the chance of a failure once for long enough to defrost food in 25 years I would say as around 90%, and it only needs it to happen once to pay the extra cost of having a third RCD. .... To have a third RCD looking at less than £20, can't see how anyone's maths can show not worth the extra, even if only in peace of mind.

It's not the maths, per se, but the underlying assumptions which are the issue.

In the ~35 years I have lived with freezers (always more than one) protected by RCDs, the only significant 'freezer failures' we've suffered have been failures of the freezer itself, not of its power supply - so any 'device trips' have been the result, not the cause, of the freezer failure.

Furthermore, I have always (deliberately) had freezers supplied by circuits (e.g. kitchen or living room circuits) whose failures would be rapidly noticed (if the house was occupied), so there is only a potential issue (no matter what sort of protective device is involved) if the house is unoccupied for appreciable periods - which, in our case, is very rarely. Taking that together with the fact that (unlike your experience) 'unexplained RCD trips' are almost unknown in our house (despite very many RCDs) means that the probability of a freezer being 'lost' because of an RCD trip occurring 'coincidentally' during one of the very rare periods when the house is unoccupied must be extremely small.

In fact, since (given that the house is very rarely unoccupied for appreciable periods, and that freezers are supplied by appropriate circuits), none of the freezer failures have gone unnoticed for an appreciable period of time, we have never 'lost the contents' of a freezer - so that, in our case, the maths has no financial 'losses' to balance against the cost of implementing measures to minimise losses!

I was happy with my 14 way RCBO CU when we had a roof leak and some sockets got wet, I simply left the circuit tripped for a few months until repaired, had it been a twin RCD box I would have needed to have opened the CU and disconnected that ring final, not a big job for an electrician, but not so easy for the normal home owner.

A few months?! Whenever I've suffered (understandable, not 'nuisance') RCD trips due to water ingress into electrical accessories, once I have 'released' any actually trapped water, it has usually only been a small number of hours, never more than a day or two at most, before things had dried out enough for me to be able to re-energise the circuit without the RCD tripping.

So yes the era of two RCD's is gone, save for a few penny pinching landlords.

I think we have established that interpretations of "the era of ..." vary so much as to render it a fairly useless, and potentially misleading, phrase!

However, it's certainly not only 'penny-pinching landlords'. None of the re-wires/CU changes undertaken by/for owner-occupiers I have been aware of in recent times (out of interest, I pay attention to such things!) have involved all-RCBO CUs being installed - most have been dual-RCD ones , and a few 'high integrity' ones, with 2 RCDs, several MCBs and a couple of RCBOs. If one takes sparkwright's view, one would presumably have to conclude that all of those must have been installed by 'non-discerning' electricians!

Kind Regards, John

 

[plugwash]

All of those are entirely different from installing consumer units which comply with BS7671.

But ultimately what matters is not your interpretation of BS7671, but the interpretation of the self-certification schemes that electricans are practically forced to join.

As long as dual-rcd CUs are still allowed by those schemes and as long as they remain the cheapest option, you can expect many of them to get installed.

 

[JohnW2]

... In fact, since (given that the house is very rarely unoccupied for appreciable periods, and that freezers are supplied by appropriate circuits), none of the freezer failures have gone unnoticed for an appreciable period of time, we have never 'lost the contents' of a freezer - so that, in our case, the maths has no financial 'losses' to balance against the cost of implementing measures to minimise losses!

I should have added ... the main reason why we never 'lost the contents' when freezers (not their power supply) failed whilst the house was occupied is that all of our freezers have 'over-temp' alarms (which also do detect failure of power, but that was not relevant in most cases, except those in which primary failure of a freezer actually caused a device to trip).

Kind Regards, John

 

[SUNRAY]

I should have added ... the main reason why we never 'lost the contents' when freezers (not their power supply) failed whilst the house was occupied is that all of our freezers have 'over-temp' alarms (which also do detect failure of power, but that was not relevant in most cases, except those in which primary failure of a freezer actually caused a device to trip).

Kind Regards, John

Of the 7 or 8 freezers I've had anything to do with only 2 have failed and both were still running but not cooling sufficiently (and both were full for Christmas) allowing us to use everything well before near to going off, even the melting icecream was used in place of milk, either dringing or in desserts. Not opening the freezer in times of power loss kept it frozen for many hours.