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RCD protection in Bathrooms


davetheglitz

Question

Just started doing some work for a bathroom installer.

If double insulated downlighters are installed in a bathroom do they need to be RCD protected? Can't see any reason why they should - but am I missing something?

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23 answers to this question

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if you touched live and neutral your still earthed via everything else you would have to draw 55ma to die as you say. but the rcd will trip well before that at 30 and hey presto you live.

the very reason that rcd's save you

But, if you are insulated from paths to earth ie your wearing rubber soled shoes whilst standing on an insulating mat, and you simultaneously touch line and neutral conductor, then their would be none or very little current flowing to earth. However all of the current flowing in that cct would now flow through your body from the line conductor to the neutral which is normally gonna be in amps not milliamps.

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But, if you are insulated from paths to earth ie your wearing rubber soled shoes whilst standing on an insulating mat, and you simultaneously touch line and neutral conductor, then their would be none or very little current flowing to earth. However all of the current flowing in that cct would now flow through your body from the line conductor to the neutral which is normally gonna be in amps not milliamps.

Path of least reistance.

If you grab L&N in 1 hand it will only flow through that hand. You'd have to grab one with each hand for it to pass across your chest.......

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a double insulated down light cannot exist by its very nature

an rcd will protect you from L-N

what do your feet and taps have to do with it

Please don't try the experiment of connecting yourself between live and neutral and expect an RCD to save you!! The available current is limited only by the fuse/MCB. More than the 30mA that can kill you - even on a lighting circuit!

To elecrtocute yourself on a bathroom lighting circuit you have two options:-

  • Connect yourself between live and neutural
  • Connect yourself between live and earth

Live to neutral your a goner.

Live to earth when changing double insulated lights - you need to have access to earth. Bathrooms are special locations because of wet skin contact.

Who changes lamps in a bathroom with no clothes on whilst they need a tool to access the lights? If they do what is the chance of being in contact with a good earth - must have your feet on the taps to provide this!

More importantly who changes lights with the lights on - downlighters will give no access to loop in connections - so if the switch is off where is the risk?

Regs are regs - but how can you sell what you don't believe!

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and RCD does not 'limit' current.

Spot on. I've seen in a few threads recently people saying that with a 30mA RCD you can't have a earth fault current of more than 30mA, or words to that effect.

Of course once the earth fault current reaches 30mA the RCD will trip, but in the 30ms or so that it takes to trip, the current may well increase to much higher levels, hence you can feel the shock when 30mA is apparently imperceptible to humans.

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an rcd will protect you from L-N

please explain? so in that case, why does the RCD not trip when a load is applied to live/neutral?

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Also an RCD will not protect you from making a circuit L-N - which with a downlighter is a more likely scenario than touching switched live while firmly planting your bare feet on a nearby tap.

even if downlighters is DI, there is still a chance of touching live. very unlikely, since light would have to be removed. if you do somehow manage to touch the live, then the RCD should disconnect supply. you dont have to be standing on the tap either - juts about everything will conduct, so you will still get a shock. although on a dry wooden floor, its more likely to a slight tingle due to high resistance

and whats that about needing a tool to remove downlights? unless your using some weird fitting, all downlights can simply be pulled form ceiling.

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please explain? so in that case, why does the RCD not trip when a load is applied to live/neutral?

because some of the current will be leaked.

if thats not the case rcd's are useless

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ALL circuits need RCD protection. No functional earth needed for the RCD to operate.

an I'm a vet ;)

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Just started doing some work for a bathroom installer.

If double insulated downlighters are installed in a bathroom do they need to be RCD protected? Can't see any reason why they should - but am I missing something?

Its:-

Bath & Shower rooms..

reg 701.411.3.3 Additional protection by RCD's

ALL circuits in the location need 30ma RCD protection!

Page 166 of big red ...

:|;)

wot scuppers your plans Dave!!!:(Guiness Drink

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My thoughts on downlighters were are they in the bathroom or above it? If IP rated no live connections could be touched from below without using a tool. Also an RCD will not protect you from making a circuit L-N - which with a downlighter is a more likely scenario than touching switched live while firmly planting your bare feet on a nearby tap.

I've gone with the big red book - but I can forsee problems with some installations.

Thanks SL!

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a double insulated down light cannot exist by its very nature

an rcd will protect you from L-N

what do your feet and taps have to do with it

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a double insulated down light cannot exist by its very nature

an rcd will protect you from L-N

what do your feet and taps have to do with it

Sorry Lostit but you are incorrect double insulated downlights do exsist.

http://www.double-insulated-lighting.co.uk/class-2-recessed-lighting.htm

I would suspect the first ammendmants to the 17th edition will be clarification on all circuits entering a bathroom, a rcd will offer very little protection if any to a class 2 fitting.

However, under the current regulations they must be rcd protected.

You can use mains voltage lighting in the bathroom, providing the IP rating is adequate for the intended use.

I personally would never place a mains voltage light above a shower though, prefering to use a 12v instead.

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A L to N fault is a short cct and not a leakage of current to earth, therefore the RCD would nt pickup this up as there would be no imbalance of current between the L and N coils inside the rcd and so it would not trip.

If the L-N fault was of negligible impedance then a sufficent current would then be produced and then only the circuit breaker would disconnect especially if the terminals were enclosed in a class 2 fitting.

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because some of the current will be leaked.

if thats not the case rcd's are useless

that doesnt explain how an RCD will protect you against a L-N shock. an RCD will only protect between live and earth.

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Dear Mr. It. (Or can I just call you "lost"?)

The ONLY thing that will save you from dying if you`ve got phase in one hand, and neutral in the other, is LUCK!!!!! Pure & simple.

If it isn`t SUPPOSED to be live, but is, then the RCD will see THAT as a fault.

I understand your supposition that there would be leakage through your body; but remember the "path of least resistance" rule?? The neutral will be a far, far better path, in all likelihood, and it is possible that less than 30mA would leak.

FYI, death can be caused by as little as 80mA!!!!!

immaterial if that is to earth, or neutral. If it goes through you, your body won`t care where it went after.

Does that make a little more sense, mate?

KME

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Dear Mr. It. (Or can I just call you "lost"?)

The ONLY thing that will save you from dying if you`ve got phase in one hand, and neutral in the other, is LUCK!!!!! Pure & simple.

If it isn`t SUPPOSED to be live, but is, then the RCD will see THAT as a fault.

I understand your supposition that there would be leakage through your body; but remember the "path of least resistance" rule?? The neutral will be a far, far better path, in all likelihood, and it is possible that less than 30mA would leak.

FYI, death can be caused by as little as 80mA!!!!!

immaterial if that is to earth, or neutral. If it goes through you, your body won`t care where it went after.

Does that make a little more sense, mate?

KME

you just backed my argument up ROTFWL

so in order for someone to die you say 80ma? lets have a compromise then and go half way between 30ma and your 80 so 55ma.

if you touched live and neutral your still earthed via everything else you would have to draw 55ma to die as you say. but the rcd will trip well before that at 30 and hey presto you live.

the very reason that rcd's save you.

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the mcb will trip, may be not quick enough to save u?

an mcb won't tom because it could flow well more than a human can take

but an rcd will limit the current to 30ma hence saving you

not from shock but death

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the mcb will trip, may be not quick enough to save u?

unlikely to be enough current flowing through you to trip MCB. and if there is, your probably dead

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an mcb won't tom because it could flow well more than a human can take

but an rcd will limit the current to 30ma hence saving you

not from shock but death

and RCD does not 'limit' current.

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