Currently I have a split load consumer unit, boths sides have their own 30mA RCD It is split into lighing one side, and everthing else the other.
I am adding a second CU for non-RCD protected things (Alarm, freezers and feeds to smaller comsomer units in the shed & garage)
Would it be advisable to put the oven and induction hob feeds on this non RCD CU?
Sparks...
Hi Sparticus,
You should put the hob and oven on an rcd protective device if one is available, obviously if they are not on rcd it will still comply with the iee 16th ed regs (excluding outside/garden barbecues/sockets, etc), though if you have a circuit available with rcd protection for the hob/oven then use it.
You shouldn't really put lighting circuits on rcd protective circuits, hence the idea of a split consumer unit, as a trip of the lighting causes a hazard in itself, also alarm circuits i.e. fire/intruder (without outlets should be dedicated circuits) should also not be rcd proctected for similar reasons.
Regs Alan
Sparks wrote:
I have always been amazed in this day and of implied safety, you're still allowed to have bare connectors associated with light fittings without any protection at 230V AC.
What do you think will be in the 17th Edition?
The house is a TN-S (Supplied by the electricity company's cable)
Incedently, this earth wire from the head to the CU seems to be about 4mm or
6mm - is this normal, or should it be replaced with heavier cable?If so, do I ask the electricity company, as it is sealed in the lower part of the cable head?
Sparks...
So, for the fridge and freezer, should these be hard wired, so not having a socket on an unprotected circuit?
Sparks...
My preference would be to put those fixed loads on the non RCD side. The Regs certainly don't require them to be RCDed; and the older your oven and grill elements get (also radiant and 'sealed' hotplates, but not induction plates as you have) the more they pass a small leakage current, especially when cold and a little damp (e.g. after a steamy baking session as the elements cool down). Putting these on a shared RCD predisposes that RCD to nuisance tripping.
But if you prefer the added reassurance that slopping salty spud-boiling water about will cut the supply should it drip where it shouldn't, there's nothing deeply bad about putting it on the RCD side. You could always (assuming enough slack at the CU end) start off with it on the RCD side, and move it across to the non-RCD CU if you get nuisance trips which sort-of tie in with turning the cooker on.
In my direct experience of this, with a whole-house RCD (as used to be the fashion), young kids (so making me keen on keeping the whole-house RCD until they were past the fingerpoken age - 85, isn't it? ;-), a coupla 'emergency' lights which came on if the power failed, and a growing number of switched-mode-PSU computers and mains-filtered appliances, *oh* and an RCD which on test showed it'd trip at under
14mA! - it was still only rare that turning on the cooker ring/grill would make the RCD trip immediately; rather, it'd pop a minute or two after you'd started to use the cooker. Maybe an element had to expand a little first to bring a live conductor close enough to the earthed casing to leak enough... maybe it was just pixies at work ;-)HTH - Stefek
It comes down to which is the greater danger, being plunged into darkness or being electrocuted...
FWIW our lighting circuits are RCD protected and are staying like it ;)
Lee
Why have you got 2 RCD's are you sure they are both RCD's? If so I'd remove the one supplying the lighting and add the other circuits to it, if you have room and don't overload the cu!
If the oven switch has a 13 amp outlet on it then it must be rcd protected, otherwise up to u.
I can think of few downstairs sockets *less* likely to get an outdoor appliance plugged in than the one permanently occupied by the householder's kettle - so I don't understand why you hold with such certainty that a cooker-control unit with integral socket 'must' be RCD protected...
So, if it was compliant at some point, it would still pass an inspection now?
If that is that case. surely that is a bit stupid, as if the regulations have changed, the older ones must now be deemed unsafe?
Sparks...
They don't need RCD protecting, and oven elements can cause tripping whilst not presenting any significant electrocution risk which means it's not a brilliant idea to have them sharing an RCD with anything else. So normally, they go on the non-RCD protected side.
Another thing I should have said, or asked, What type of earthing system do you have? If it's a TT system, you can't normally have any non-RCD protected circuits (except possibly for some low current ones if you can prove the earth fault loop impedance is OK for them). This might be the reason you have all circuits RCD protected (although some of them should be at >= 100mA).
That one is a complete no brainer.
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 DIY!). Those figures have not reduced since whole house RCD's started to be used but are expected to rise with Part P dissuading people from installing extra sockets and increasing the use of extension leads.
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.
I suggest you invest in a book on basic risk assessment.
What benefit will this bring?
It will have been compliant when installed - maybe, say 14th Edn of t'Regs. Theze Dayz it'd be 16mmsq or so. Not sure there's a *vast* benefit in getting the supply co out to upgrade - they may then want you (or at least suggest you should) up the rest of your own bonding to
10mmsq/16mmsq, and/or PMEify you...
Just because we chose one slight benefit over a possible risk does not mean that we are unaware that risk.
We are unlikely to fall down stairs we don't have, for instance...
Lee
Yes. There's no point in RCD protecting permanently connected devices like this - and since they may well have mineral insulated heating elements might cause nuisance tripping.
I tend to agree. I know the arguments about a blown bulb plunging the house into darkness - but think the hazards of Joe Bloggs replacing a bulb on a possibly live circuit more of a risk. IMHO.
Sparks wrote: >
No - there's every difference between 'unsafe' and 'not to latest standards for a new installation'. There's no obligation to keep an installation continually updated in line with Regs changes (though I bet the NICEIC would *lurv* such a principle to be established). There's a specific category for 'not in line with latest Regs but not presenting any problem' on the standard Periodic Inspection form (scrabbles for OSG: ah yes, here it is.) There's a 4-level "recommendation" scale, thus: "1 - requires urgent attention; 2 - requires improvement; 3 - requires further investigation; 4 - does not comply with BS 7671:2001 amended to . This does not imply that the electrical installation inspected is unsafe."
HTH - Stefek
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