I am contemplating fitting an RCD (Residual Current Device / Earth Leakage Relay ) in the power supply to my house between the meter and the fuse box.
The problem with doing this is that it could involve some hot wiring which I dont much like. So I have some questions:
a) The safest procedure looks to be to pull out the Electricity Board (or who ever they are now) Fuses but I would have to break the seals and this might annoy them. I have never tried doing this, I just assume that it is possible and reasonably easy.
b) I could break the seals on the meter and disconnect the wires, coming from it. Again this would no doubt annoy the Electricity Board, but looks to be quite easy and would involve minimal hot wiring, and I would not have to tamper with the fuses.
c) I could hot wire the whole job, I am helped by the fact that there is a join in the cables, but it would still be a bit tricky.
d) Can anyone advise me of any safe working practices for hot wiring?
e) If I paid a non Electrify Board electrician to do the job how would he approach the problem?
I would happily post in a more relevant news group if I could find one.
Whole-house RCDs are deprecated and are contrary to the IEE wiring regulations. It is unacceptable to lose power to lighting and smoke alarm circuits in the event of an earth leakage on a power circuit. If you will google this subject on news:uk.d-i-y you will find anecdotal evidence that whole-house RCDs may cause more deaths through sudden lighting failure causing a person to fall, than are caused by electrocution annually.
The only requirement for whole-house RCDs is in an installation with TT (earth electrode) earthing, when it should be a 100mA time-delay RCD and the power circuits should be protected by 30mA RCDs such that proper discrimination is obtained.
RCD protection should be provided to power circuits either using a 'split load' Consumer Unit where the power circuits are run through a 30mA RCD but the lighting circuits are not, or through individual RCBOs for each circuit, which combine the functions of MCB and RCD.
| The problem with doing this is that it could involve some hot wiring | which I dont much like. So I have some questions: | a) The safest procedure looks to be to pull out the Electricity Board | (or who ever they are now) Fuses but I would have to break the seals | and this might annoy them. I have never tried doing this, I just | assume that it is possible and reasonably easy.
You should only have one service fuse, and the "board" don't usually mind too much if that is pulled. Ensure it is pulled and replaced when no current is flowing.
| b) I could break the seals on the meter and disconnect the wires, | coming from it. Again this would no doubt annoy the Electricity Board, | but looks to be quite easy and would involve minimal hot wiring, and | I would not have to tamper with the fuses.
This *will* annoy the electricity co and does not remove the need for hot wiring; you are still handling live terminals on the meter. If you were going to do this you should pull the main fuse, remove the meter tails from the existing CU and connect to the RCD supply terminals, and provide new meter tails from the RCD load terminals to the existing CU. You should not open the seals on the meter.
| I would happily post in a more relevant news group if I could find one.
copied to and follow-ups set to uk.d-i-y That ng has an extensive FAQ section at
Our CU is a split load, the sockets are run off a 100A/30mA RCD (Via MCB's)
The lighting is run off a 40A/30mA RCD, again via MCB's
This was apparently installed when it became apparent I was very interested in electricity at a very early age!
Is this arrangement not allowed, as IMHO there is more risk of electrocution when some dopey tw*t tries to change the dead bulb with the switch still on than the same dopy tw*t unplugging something when it is switched on!
If someone was up a ladder, using a power drill for example, and the drill caused an earth fault, the sockets RCD would trip, leaving the lights on in my setup.
Personally, I'd remove the lighting RCD. Even with it on, you'll still get enough jolt to knock you off the ladder, and you are unlikely to electrocute yourself with a pendant fitting.
Loss of a lighting circuit can be very dangerous, especially in a fire, or whilst in a dangerous position, such as up a ladder.
Often, the easiest way to add RCD protection to an existing installation (using DIN rail CU) is to replace socket circuit MCBs with single width RCBOs, if they are available. It isn't necessarily the cheapest way, although if there are only 1 or 2 circuits to be protected, it can still be cost effective. It is certainly the best way to do it, however many ways there are.
It is a classic example of the original specifier not understanding risk at all and making things more dangerous by installing "safety" measures.
Putting an RCD in stops you being electrocuted whilst changing a light bulb. As far as I can find out the number of people killed or admitted to hospital from domestic premises in the UK for this reason in the last 10 years is precisely zero.
On the other hand in the same period hundreds have died and thousands been injured in fires at night. Many more have been killed or injured in falls down stairs at night. Lighting RCD's regularly trip if a bulb blows (especially on switch on) and trip very quickly in a fire as combustion products create leakage paths in wiring. Both circumstances create risks considerably greater than the trivial one of electrocution while changing a bulb. The last thing you want in a fire at night is the lights going out on you.
Well, the only person I know personally who's received a serious electric shock at home received it from a wall-mounted (i.e. fixed) light fitting, while she was changing a light bulb.
No they don't, that's the MCBs which trip. And *their* installation is considered to be a good thing.
I think that to form a balanced opinion at this point, we also need to know what proportion of fires are caused by electrical faults which might have been detected by an RCD.
I've just spent 9 years living in a house with a 30mA RCD covering the lot, with a 6A MCB on the lighting circuit. The former is frowned upon, the latter is supposed to be good.
The former *never* tripped except when there was a fault on an appliance. The latter tripped on probably 60% of bulb failures, as often as not requiring a journey downstairs in the dark (have you seen the number of people that die in stair-falls) to reset the breaker. If suddenly plunging a house into darkness is a dangerous, then so are typical 6A type-I (B, nowadays) MCBs on lighting circuits.
You're very acurately restating uk.d-i-y received wisdom on the subject (as a grandee, perhaps you're the origin of it :-), but it doesn't match my experience.
No, it is incandescent light bulbs which are dangerous and should be banned. Lighting circuits intended to have incandescent monstrosities may be better equiped with a 5A cartridge fuse holder (and supply of fuses).
I too know of someone who did the exact same thing - they were thrown across the room (No RCD)
Same here, out RCD has never tripped when a bulb has popped - The MCB's do The blowing of the bulb causes over current, not leakage.
I would always have a seperate MCB on the lights, especially if there were inquisative kids about.
Is it a requirement to have no RCD, or is it mearly a suggestion? (Not that it's getting changed anyway)
I fell there is far more risk of someone poking their fingers in the fitting while it is on, then there is of a fire breaking out - how often are [regular GLS] bulbs changed compaired to how many times fires break out in a house?
I have installed an emergancy light in the cupboard where the breakers are, If the lighting trips (or there is a power cut) this illuminates
Yes, but the shock is rarely fatal or injurous, just painful and embarassing. The nature of the fitting doesn't lend it to maintaining a solid grip on you long enough to cause electrocution.
And quick frankly, if you electrocute yourself changing a bulb, you're probably capable of removing yourself from the gene pool in a much more spectacular fashion.
The reason not to install an RCD is because lights failing is a demonstrable and measurable cause of death either during house fires, or from sudden darkness during a dangerous task (such as operating machinery, or balancing on ladders). Electrocution from changing light bulbs doesn't figure in the statistics.
...just imagining frail old lady holding [Earthed] wall light to steady herself with one hand, and attempting to get the new bulb in with the other, and decides as she cant see the hole (its above her head) she fells around for it with her hand.
It must happen...
Well, it ain't always me that changes light bulbs, if you get my drift
demonstrable
That's why there are two RCD's - one for the lights, and a separate one for the sockets (and an emergency light above the CU!)
Basing a judgement of low probability events on personal experience is never wise.
RCD's regularly trip when bulbs blow.
Not very many. About 20 deaths a year are caused by fires where the cause is known after proper investigation to be an electrical fault. This is about 4% of the total who die in house fires.
The following are based on 1999 figures from the Home Office.
The number of people killed or severely injured by electrocution in domestic accidents the UK each year is very small. Even if you include accidents which are not electrocution but attributable to it (such as falling off a ladder after touching a live cable) the numbers involved in domestic accidents are still small, about 25 deaths and 2000 injuries of all severities (compare this with 70 deaths and 40,000 injuries caused by general DIY activities). Those figures have not reduced since whole house RCD's started to be used although the number of electrocutions in the garden (listed separately in the figures) has fallen.
The total number of people killed in accidents in the home each year is about 4,000, of this roughly half are due to falls and about 1,000 due to falls down stairs.
The number of people killed or injured in house fires is also depressingly large, many times greater than those killed by electrocution. Typically 500 people die and 18,000 are seriously injured each year by fire in the home.
Of these deaths about 20 are attributable to electrical fires some of which an RCD might have prevented. The remainder are caused by non-electrical ignition.
Of the 4,000 people killed in both falls and fires each year there is no easily available breakdown of contributory factors. However some police and fire reports do give further information. Of these I have seen only a very small number from one area, however within these there were a significant minority, probably about 10-20 which mentioned that lights were out and could not be turned back on from the light switch when the emergency services arrived. Only one or two of these, usually fire service reports, specifically mention RCD's having tripped. Nonetheless it is reasonable to infer even from this imperfect data that the number of people killed in falls and fires in which tripped RCD's were the cause or a major contributory factor is significantly higher than the number of people protected by them _in the home_. In the garden or garage is quite another matter.
Of the 20 odd houses I have lived in most had 30mA RCD's covering everything and the majority of those would quite consistently knock everything off at the slightest provocation and especially if bulbs failed.
As has been pointed out the danger is in using inappropriate lighting. If the design of the house or the condition of the occupants makes a fall likely don't fit incandescent bulbs in lights needed for safe navigation of stairs.
Indeed I suspect I am.
My experience is of lifting the burnt corpses of family out of the way of the locked front door they had died against while trying to break it down to escape the fire which killed them. The key was on the floor under the body of the youngest child, the door was covered in blood from their hands. By the time they were found there was no consumer unit remaining but the neighbours all said they had seen no lights on in the house as the fire developed. Did they die because of the fathers love of securely locking the doors or because they couldn't see where the key fell? I don't even know if the house was fitted with an RCD but in view of the date and the fact it was a renovated council property I suspect it had a single whole house 30mA RCD.
However, as I said earlier, relying upon personal experience is unwise. The reason I won't have RCD's on lighting circuits in the house (now I have a choice) is based upon evidence, not experience.
They shouldnt, as RCD's will trip only if there is an imbalance between the live and the nuterual, when a bulb blows, it causes an overcurrent, this is when the MCB's trip as there is no earth inside the bulb, there cant be an imbalance.
This is not good, as has been previously mentioned - I still cant understand why an RCD is tripping on a bulb failure..(maybe it is faulty, or is under rated?)
Just out of interest, why not?
Do you mean fir CFL's, or am i missing the point here!
.
We have already agreed that a whole house RCD is bad. This is NOT what I am suggesting here!
Can you propose a mechanism for this? The only one which comes to mind would be that you already had a neutral-earth leakage fault, and the rise in neutral current caused by the bulb-failure arc was sufficient to create a leak to earth.
It wouldn't matter what kind of lamp illuminated the stairs if the lighting circuit had tripped.
Yes, but you're a (former?) member of the emergency services, aren't you? As such, I have every sympathy with the gruesome sights you might have had to deal with in your chosen profession, but I do believe that members of such services are uniquely *ill* placed to give general advice about risks to ordinary people.
To a fireman, a horrible death in a house fire is a common occurence - to me, as a resident of a non-smoking household, it's extremely unlikely to be the cause of my, or my family's demise. Personally, if I'm doing the neurotic parent bit I worry about road safety a darn sight more.
TBH, if you know of a property that has an RCD which trips when light bulbs blow, then you ought to advice the occupants to get the wiring fixed.
Well said Peter. You are probably a voice in the wilderness, like that chief inspector who categorically stated that 'excess speed is the cause of less than 7% of accidents' and 'speed cameras do not (statistically) reduce road deaths'.
I am definitely with you on this. My 30mA RCD tripped about 50% of the time when any bulb blew, with the MCB about 60%. Sometimes both.
Its bloody dangerous feeling down te saircase to get to the consumer unit, especialy if you have left the casing off...:-)
You haven't thought it through. there is ALWAYS some neutral earth leakage. It occurs every time an oh so rigorously RFI suppressed switch mode power supply (TV, computer, monitor, LV lighting) or any suppresed motor is plugged into the circuits. Enough of these and the 30mA RCD is on a hair trigger. Any voltage surge and over she goes.
Here it was a toss up whether the RCD. MCB, or both would go.
Now with a 100mA RCD, its not gone since.
Whether or not I install RCBO's in the few circuits the regs demand depends on the building inspector.
Proper standrads of wiring and better plugs, sockets, and particularly the use of double insulation and plastic cases have done far far more to reduce shock hazard than RCD's.
I can clearly remember getting shocks of metal fires, whose earthing wwas poor or nonexistent, and whose rubber coated wires frayed all too easily. Now we seldom have metal frames, and we don't have users installing their own plugs nuch either.
I have just explained why.
Actually, I think its quite good, provided it trips only when there is a significant dangerous fault.
There is always some leakage from both L & N to earth. If nothing else due to the capacitance between the miles of T & E laid over the house. And more especially in all the capacitors used to RFI filter electronic devices.
There is always some inductance in the supply, due to cable lengths
and transformer secondaries. High speed switching currents will
Reading this, and especially the very sad ending to Peter's post makes me think that it would not be a bad idea to add emergency lighting as something that should be included in Building Regulations for new properties and incentivised for others in some way, especially for the elderly and others with mobility difficulties..
We already have mains powered smoke detectors as an addition, basically to get over people taking the batteries out or forgetting to replace them.
Non-maintained small fluorescent lights are not very expensive, although the fittings are pretty ugly. Undoubtedly this could be improved if there were a consumer premises market for them.
It would seem to me that the populace would be better served with a lighting measure like this rather than the mandatory low energy lamps stuff. In fact with a bit of creativity, both objectives could be met in a single package.
I am not sure what sort of size and power level that they would need to be to provide sufficient light say at the top and bottom of a staircase in a fire, but to be able to see adequately during a power cut, then the little 8w ones are probably enough.
I have my consumer unit at the back of a cupboard in the kitchen and it would not be easy to see in the dark. I fitted a small maintained fitting, run from a (non-RCD ptotected) lighting circuit and operated also by a plunger switch on the cupboard door. Thus I have a light over the CU for when I want to work on it with the power deliberately off and also to be able to see the breakers after a trip.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.