Bathroom Light Switch

[securespark]

I was thinking about RCD protection in a bathroom while I was in the shower last night. Yeah, I know, it's sad. Regular guys have much better things to think about in the shower!!

I was thinking it is a risky strategy to trust an electro-mechanical item to save your life when you are wet, naked (or even damp and not naked) and in contact with low voltages.

We know RCD's do not prevent contact with voltages. In some cases, they do not operate at all, even if the mechanism is healthy.

What are the chances of an RCD preventing injury or saving a life in a faulty shower situation?

Are there any stats on this?....cos I sure as heck don't want to put the theory to the test!!

 

[adrian.groves]

Thank you for all of the replies.

It is interesting to see that the regs don't prohibit the use of wall switches in the bathroom just not where you could reach them from the bath /shower. Since in my case you could just about reach it from the shower(or definately reach it with one foot in the toilet) I will use a pull chord for the main lights and a wall switch outside for the mood lighting.

Thanks for the help, i now know that the guy who made the suggestion was not a fool.

 

[EFLImpudence]

Do RCDs ever get the chance to save anyone while having a shower?

We know RCD's do not prevent contact with voltages.

The plastic casing does, though.

Some electric showers have (or did have) a metal outlet from the can which, if you connected a metal hose, could present a fault but doing that would be foolish.



John has asked before if an RCD has ever saved a life.
I don't see how there could be any stats. How would anyone know?

 

[PBC_1966]

Is there a perception/believe that a 5mA device will give appreciably more protection than a 30mA one? I suspect that they don't disconnect much, if at all, more rapidly than do 30mA ones, and, particularly in the context of potentially wet skin, L-E shock currents are likely to be well in excess of 30mA (even at US voltages).

It's been some years since I read about the specific development of the GFCI in the 1960's, but if I recall correctly the 5mA level was chosen based upon the maximum "let go" current for the majority of people. The specifications require that the GFCI must trip at an absolute maximum of 6mA and must not trip at a sustained 4mA. Again, if I recall correctly, I believe the maximum allowable trip time is 25mS, but I have in mind that that's specified for a ground fault somewhat above the 5-6mA level.

 

[stillp]

We know RCD's do not prevent contact with voltages.

Actually they do, by disconnecting the supply if an earth fault occurs that has too high a fault loop impedance to trip an MCB. The fault current that trips the RCD doesn't have to flow through a person.

 

[stillp]

A lot of hotels in the US seem to ignore that. I've often seen a hairdryer provided and a socket-outlet above the washbasin to plug it in to.

The complete prohibition referred to is for the British IEE Wiring Regs. 13th edition.

Sorry, mis-read your post.

 

[PBC_1966]

A lot of hotels in the US seem to ignore that. I've often seen a hairdryer provided and a socket-outlet above the washbasin to plug it in to.

The complete prohibition referred to is for the British IEE Wiring Regs. 13th edition.

Sorry, mis-read your post.

It happens to all of us from time to time!

Far from prohibiting sockets, the NEC actually requires every bathroom to have at least one receptacle outlet for convenience of use by the wash basin. The current rules (at least as of 2008) state that it must be within 3 ft. of the basin on a back wall or side panel, or may be mounted on the front or side of the supporting cabinet no more than 12 in. from the top. I'm not sure exactly when the specific distances were introduced; older rules just said one must be provided adjacent to the basin location (that goes at least as far back as the 1971 NEC).

Also, with the proliferation of the ridiculously high-powered hair dryers around today, there was a new rule introduced in, I think, either the 2002 or 2005 code requiring a separate 20A circuit for bathroom outlets. Previously they could just be included on any general-purpose 15 or 20A circuit serving other parts of the house (subject to having GFCI protection from 1975 onward).

 

[JohnW2]

It's been some years since I read about the specific development of the GFCI in the 1960's, but if I recall correctly the 5mA level was chosen based upon the maximum "let go" current for the majority of people. The specifications require that the GFCI must trip at an absolute maximum of 6mA and must not trip at a sustained 4mA.

Fair enough. In some senses, it's obviously a case of 'the lower the better', but I still suspect that the majority of potentially serious shocks are going to be well over 5mA, probably well over 30mA.

Although I seem to have been extremely lucky (virtually immune, despite having lived with many RCDs for many years) but, as you know, we are always hearing over here about 'nuisance trips' with 30mA RCDs - what are the experiences with a 5mA trip threshold?

Kind Regards, John

 

[JohnW2]

John has asked before if an RCD has ever saved a life.

I have indeed - although I do usually qualify the question by conceding that one imagines that "there 'must' have been at least some cases" in which an RCD has prevented a death.

I don't see how there could be any stats. How would anyone know?

That literal question obviously would be impossible to answer. However, the other question I have often asked (here and elsewhere) is how many people have experienced, or even heard of, cases in which an RCD has operated in response to someone receiving an electric shock - since those are cases in which the outcome might have been fatal in the absence of the RCD. However, despite having asked many people that question many times, I've still only had two or three people telling me that they were aware of a case in which a shock had resulted in an RCD operating.

Kind Regards, John

 

[PBC_1966]

Although I seem to have been extremely lucky (virtually immune, despite having lived with many RCDs for many years) but, as you know, we are always hearing over here about 'nuisance trips' with 30mA RCDs - what are the experiences with a 5mA trip threshold?

It can certainly be a problem, especially the accumulative effects of multiple pieces of equipment plugged into the same GFCI circuit each with a small amount of leakage. In fact in some cases equipment - particularly older equipment - just won't work properly on a GFCI circuit as designed, so unless one wishes to go to the trouble of running through a transformer, the only solution is to plug into a non-GFCI outlet instead (if one is convenient - which is becoming less and less so in newer homes) or pull out the GFCI and replace it with a regular circuit-breaker instead.

 

[JohnW2]

It can certainly be a problem, especially the accumulative effects of multiple pieces of equipment plugged into the same GFCI circuit each with a small amount of leakage.

How many outlets would one typically see on one 5mA protected circuit?

Kind Regards, John

 

[securespark]

If the code is logical, it ought to be no more than 1.

 

[PBC_1966]

Sometimes you'll find a single duplex outlet, but in other cases it's not unusual to find half a dozen or more duplex outlets all on the same GFCI, either by way of a GFCI breaker in the panel or by use of a combination GFCI receptacle to provide feed-through protection to outlets "downstream." As the code required more and more locations to be GFCI protected, the incentive to try and cut costs by using the least number of GFCI's for the most number of outlets certainly seems to have grown.

In our present home we moved into earlier this year, for example, we have one GFCI duplex receptacle in the kitchen on one side of the sink, which also protects two more duplexes on the counter on the other side, and - for some reason yet to be determined - also the outlet to provide power for lights & controls on the gas stove. We have a second GFCI at one duplex in the garage, which also feeds three more duplexes in the garage, the bathroom outlets, and the outside outlet on the patio. For my liking, that's far too much spread around on one 5mA GFCI, but it's clear that it was done that way to minimize the GFCI costs while providing GFCI protection to the outlets required by code at the time the house was built (plus, for whatever obscure reason, the stove outlet). I'm certainly planning on rearranging everything considerably as I rewire various sections of the house to improve upon that.

 

[PBC_1966]

John has asked before if an RCD has ever saved a life.
I don't see how there could be any stats. How would anyone know?

That's the problem with so many of these sorts of statistics: It's often only those who do not survive whatever it is who get included in the statistics. Those who do survive are typically never counted, and even if they are, there's often a substantial amount of guesswork involved as to whether they would have survived anyway even without whatever protective device is being debated.

 

[JohnW2]

Those who do survive are typically never counted, and even if they are, there's often a substantial amount of guesswork involved as to whether they would have survived anyway even without whatever protective device is being debated.

Indeed - and the other way around, too. The non-survivors of electric shocks will inevitably include at least some (e.g. those who suffered L-N shocks) whose deaths could not have been prevented by any sort of protective device.

Kind Regards, John