The only *certain* way, that's true - but you must admit that Sod's Law was operating at full force in the case that you experienced.
I was just trying to suggest a few things the OP (who does not have high electrical skills) could reasonably try before starting to pay for an electrician.
Which has reminded me of something someone else mentioned earlier which is nearby heavy users of electricity, particularly if the house is near the end of a cable. Switching of motors, welders, refrigeration units etc can all cause a 30mA RCD in a house some way from their location to trip.
I did say I'll get round to RCBO's or a split box one day..regulations apart, if the darned thing was tripping from a total leakage of presumably 30-40mA, it only has to pull an extra 70mA to trip now.
As for 50mA being enough to kill, you will find that about 10mA can be lethal under the wrong circumstances..and the chances of a fault being such that it would trip a 30 and wouldn't trip at 70 are fairly slender.
Yes... which brings me to a question. If we changeed from 30mA rcds for general use to 100mA, would it solve more problems than create?
NT
Yep, especially if you got hooked up across the wrong side of the supply and earth.
Really you need to get the original cause of the tripping located and cleared, anything else isn't really dealing with the problem.....
Each Class I (earthed) IT appliance is allowed to leak 0.75mA. I don't know the limit for Class I TVs, but let's suppose it's the same. A 30mA RCD can trip at anything from just over 15mA to 30mA. The maximum design leakage for a circuit protected by an RCD is 1/4 of it's trip rating, i.e. 7.5mA, which is well below the
15mA above which it might trip. 7.5mA is 10 pieces of Class I IT equipment, i.e. 5 PCs and 5 monitors, or some similar combination with TVs.If that solved the problem, then you've either got an appliance which is faulty and leaking more than it should, or too many pieces of Class I equipment on a single 30mA RCD, or a high impedance wiring fault (which are typical of dampness).
Without further qualification, this isn't true.
Without further qualification, this isn't true.
No.
It creates no problem apart from a shock hazard if you don't shove 30mA trip(s) on the outside sockets etc.
And an infringement of some regulation of course, if you don't do the above.
I have to disagree. If there is mild leakage due to damp, or too many RFI filters on too much kit, then its IMHO emninently sensible to go up a notch.
If it DOIESN'T fix teh problem then there is almost certainly a specific problem that needs addressing.
But I have lived with bloody 30mA trips popping all the time during surge conditions - lightning strikes, blowing bulbs and a crap transformer on a pole supply. Work out how much current a fairly sharp transient will shove down the earth with an accumulation of a few microfarads of various RFI filters across the live/earth..
Too many pieces of class I..lets see 6xTV's, 3xhifis, one all separates..one PC and monitor, one mac and monitor, one PABX, one masthead amp, one router, two printers, a scanner, a DSL router...a prtint server..thats 20 pieces of kit..
then there's three fridges and a freezer..two washing machines a tumble drier..
..oh and some transformerless LV lighting..all of which IIRC have mains filters..then there are 6 thermostats, probably with suppression..
Plus some other odds and ends of kit that is sometimes plugged in..
I ought to, and I will one day, put RCBOS or a split box on the three rings that have outside sockets, but I do know that even with the 100mA trip, a rain shower on an extension cable outside flipped the 100mA trip.
For me, I'd rather have the small danger of shock, than the blasted house collapsing in darkness every time a thermostat goes or a light bulb blows or there is a lightning strike on the overhead cable. That is far more likely to cause me to fall down the stairs and kill my self.
Beg to differ guv, but going up a notch from 30 to 100 might be a step too far for electrocution prevention;!..
Yes there is somewhere...
How does the crap transformer cause this?..
Yep, I know of two locations with some 20 odd computers all on a 30 ma trip, and never a problem!....
Under no circumstances, should you install a value other than a 30mA RCD for the protection of 13A household socket outlets.As already stated these are installed on socket outlet circuits; which potentially could be used for external hand held appliances; such as electric lawnmowers, hedgecutters etc. I recommend that you get a competent electrician to rectify your problem.
This is the relevant extract from the IEE regulations: -
412-06-02 The use of a residual current device is recognised as reducing the risk of electric shock where the following conditions are complied with: (ii) the residual current device shall have a rated residual operating current not exceeding 30 mA and an operating time not exceeding 40ms at a residual current of 5 IDeltan, as provided by BS 4293 BS 7071, BS 7288, BS EN 61008-1 or BS EN 61009-1.100/200/300/500mA are available but are used for Fire protection and the protection of livestock etc., not for personal protection! The replacement of a 30mA RCD with a 100mA unit would create an unsafe condition, particularly so when there is already a known tripping problem with earth leakage currents. This type of cavalier action would be a parallel, with installing a larger fuse size in an attempt to overcome a problem.
Jaymack
This just isn't accurate, but you keep repeating it.
30mA RCD protection is required on socket outlets which might be used for powering outdoor portable appliances, and socket outlets in a room such as a bedroom which contains a shower. It isn't required on other 13A sockets, although it's a good idea unless they are supplying something like a fridge/freezer, in which case they are a bad idea.Yes, but 412-06 only applies where the RCD is providing supplementary protection against direct contact, and that's only required in the circumstances I listed above for 13A sockets.
Agreed (except livestock protection, which doesn't even work with
30mA RCDs -- most animals are killed by much lower currents than are required to kill a human).
Half of them should be double insulated / Class II though?
Which is sufficient load to be on a separate kitchen/laundry circuit anyway.
That's the idea of it :-)
If the house is sufficiently technological to have six thermostats, wouldn't a couple of emergency lighting units have been an insignificant extra cost to the wiring budget at Philosopher's Hall?
Owain
"Under no circumstances, should you install a value other than a 30mA RCD for"
I don't know what point you are trying to make here, the thread is regarding a known problem with a 30mA RCD tripping on a socket outlet circuit. Implicit in the above statement is the fact that a 30mA RCD should be installed as opposed to a 100mA, You are taking the statement out of context and introducing another argument regarding the application or not, of rcd's for fridges etc. Please keep your argument germaine to the thread! Jaymack
So put a socket/integrated 30mA RCD where you intend to use external devices.
To put it in perspective about 10 people a year are killed by electrocution in the UK.
About 330 are killed in dwelling fires and about 2,000 die in falls, half of these in falls down stairs.
Some of these are people whose houses have been plunged into darkness by the tripping of RCD's.
The fitting of whole house 30mA RCD's has without doubt killed more than it has saved. It is the classic example of the unsafe safety device (and of course is no longer fitted).
100mA for a known installation. Jaymack
Now, add some more proposed facts:
100mA RCD would trip in most electric shock cases where 30mA trips now, but not all. (some people seem to think the rcd limits the shock current, it doesnt)100mA RCD would not nuisance trip in most present nuisance trip instances.
Unnecessary trips plunge people into darkness without a moment's warning. How many accidents or deaths this causes we can only guess, I dont suppose there are any figures yet. How many people are going downstairs, exiting fires, using power tools, reaching frmo atop a stepladder, carrying something hot from the oven and so on when the RCD trips we just dont know. Out of 1000 stair falls and 300 fire deaths pa, rcd nuisance trips need only cause what, maybe 1 or 2 of those to balance out the tiny increase in electrocutions that would follow from going from 30mA to 100mA general rcds.
IOW we dont know without the figures, but they seem to indicate that most probably going from 30mA to 100mA RCDs wuold probably reduce deaths. The case for it reducing non-fatal accidents is tronger.
NT
I thought I was clear, but the point was that your "Under no circumstances[...]" was incorrect, and that your citation of 412-06-02 was misleading because you failed to state its very specific applicability.
There is no "out of context" for "Under no circumstances[...]". That's the sole purpose of the phrase.
If there is only one RCD and it covers the whole house then it should be 100mA, it is safer than a 30 mA.
installation, in which case it should be slugged to give a time delay, to allow the other downstream 30mA RCD to operate; since this is also required; and necessary to prevent the inconvenience and danger when an appliance etc., causes a trip. Without going into chapter and verse, there are diagrams in the on site guide which illustrate this and the reasons for the two types of RCD. A 100mA RCD, is not safer than a 30mA RCD, the installation has to be designed to the regulations.
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