outside Lighting

[Marula]

Hi Neewbie here.

Trying to systematically resolve the wiring nightmares of previous owner. Latest one.
30Amp feed from CU goes to outside light, then via junction box then goes off the a plug socket in garage. For the time being this has been disconnected.

Two approaches I was considering.
1. Feed from garage lighting circuit. into Single gang RCB with 5 amp fuse then into wall mounting external light.
2. Take original 30 CU feed. into Single gang RCB with 5 amp fuse and then into external sensor light.

I want to make sure its safe and the correct approach. Please advise if other methods are recommended.

thanks

 

[Taylortwocities]

That 30A feed shouldn't be like that! what size cable is in this circuit?
The max fuse for lighting wiring would be 5 or 6 amp.

Power your light from the garage lighting circuit. It will already be protected by a 5/6amp fuse/mcbin teh consumer unit. so no additional

Single gang RCB with 5 amp fuse

needed.

What is an RCB, by the way?

 

[Marula]

Hey thanks. Cable size out of CU is 2.5 twin and earth.

Sorry typo RCD.

 

[JohnW2]

Hey thanks. Cable size out of CU is 2.5 twin and earth.

2.5mm² T+E is not large enough for a 30A circuit. Do I take it you mean that it is connected to a 30A fuse (or maybe a 32A MCB) in the CU? If so, you either need to get the fuse/MCB reduced to 20A or else have the cable size increased to 4mm².

Sorry typo RCD.

Fair enough - so what do you mean by a "single gang RCD with a 5A fuse"? Are you perhaps talking about a RCD-protected Fused Connector Unit? As has been said, if you power the light from the garage lighting circuit, you probably would not need the additional fuse (and probably not the RCD).

Given that:

I want to make sure its safe and the correct approach

...I think that you probably need the assistance of an electrician.

Kind Regards, John

 

[Marula]

Thanks John,

Bad explanation. It's a 2.5 fed from a 30 amp fuse. Always seems obvious when you standing in front of it.

Ok so would seem that the best approach is to take the feed directly from lighting circuit to outside light.

I read that because it's an outside light an there may be risk of water ingress, that the circuit needs to be protected by RCD. Currently I have an old style fuse box. So thought that a RCD fused spur box was required. If not, then will wire straight into the lighting circuit.

Cheers

 

[JohnW2]

Thanks John, Bad explanation. It's a 2.5 fed from a 30 amp fuse. Always seems obvious when you standing in front of it.

In that case, as I said, you need to get either the fuse or the cable changed. 2.5mm cable is too small to be adequately protected by a 30A fuse.

Ok so would seem that the best approach is to take the feed directly from lighting circuit to outside light. ... I read that because it's an outside light an there may be risk of water ingress, that the circuit needs to be protected by RCD. Currently I have an old style fuse box. So thought that a RCD fused spur box was required. If not, then will wire straight into the lighting circuit.

That's why I only said 'probably'! If the garage lighting circuit has a 5A fuse (or 6A MCB) then you don't really need an additional fuse for your outside light, but it might not be a bad idea to have RCD protection (required if any of the cable will be buried in a wall) - so an RCD fused connection unit may be the simplest answer.

However, as I said, I think you probably need the assistance of an electrician - in which case (s)he will have their own ideas as to which is the best way to do things.

Kind Regards, John

 

[EFLImpudence]

I read that because it's an outside light an there may be risk of water ingress, that the circuit needs to be protected by RCD.

That is not the reason.

RCDs are required - for sockets and new cabling in certain places without other protection; not because the light may get wet.

The water ingress may cause the RCD to operate but this is just a nuisance as the other lights on the circuit will be disconnected as well.
A double pole switch, which can be switched off, controlling the outside light will enable the other lights to be used until the water is removed.

 

[JohnW2]

That is not the reason. ... RCDs are required - for sockets and new cabling in certain places without other protection; not because the light may get wet. ... The water ingress may cause the RCD to operate but this is just a nuisance as the other lights on the circuit will be disconnected as well.

Not if the RCD FCU is (as I think the OP is suggesting) supplying only the outside light.

The rest of what you say is true in terms of 'requirements'. However, if the outside light can be touched, particularly if it's Class I (and, yes, I have some ), I think that there is an argument for RCD protection being desirable - after all, for many years there has been a requirements for RCD protection of sockets which are likely to be used for outdoor equipment - which is conceptually not that much different. Do you disagree?

Kind Regards, John

 

[EFLImpudence]

Not if the RCD FCU is (as I think the OP is suggesting) supplying only the outside light.

Sorry, yes, missed that bit.

However, if the outside light can be touched, particularly if it's Class I (and, yes, I have some ), I think that there is an argument for RCD protection being desirable - after all, for many years there has been a requirements for RCD protection of sockets which are likely to be used for outdoor equipment - which is conceptually not that much different. Do you disagree?

I do disagree as far as requirements are concerned.
I don't think any appliance in itself is required to be RCD protected.
Isn't it the 'holding' which is the main criterion; not merely touching?
Plus, of course, the flex.

After all, with a Class I light, what can happen for an RCD to be advantageous for a person?

As for desirable, that would be up to someone who thinks RCDs save lots of lives.

 

[JohnW2]

However, if the outside light can be touched, particularly if it's Class I (and, yes, I have some ), I think that there is an argument for RCD protection being desirable - after all, for many years there has been a requirements for RCD protection of sockets which are likely to be used for outdoor equipment - which is conceptually not that much different. Do you disagree?

I do disagree as far as requirements are concerned.

That's not really disagreement - as would have been apparent if you had also quoted my immediately preceding sentence ("The rest of what you say is true in terms of 'requirements'.").

Isn't it the 'holding' which is the main criterion; not merely touching?

What is 'mere touching' other than brief 'holding? (electricity moves quite fast!)

After all, with a Class I light, what can happen for an RCD to be advantageous for a person?

What about if it developed an L-E fault of sufficiently high resistance (water?) for an OPD not to operate, but low enough impedance to be a problem if an 'earthed' person (e.g. standing on ground with bare feet) were to touch an exposed-c-p.

As for desirable, that would be up to someone who thinks RCDs save lots of lives.

Sure, but we have to accept that a lot of people believe that - and we also have to accept that sooner or later (even if it hasn't yet happened, which it probably has now and again) RCDs will save at least a few lives.

Kind Regards, John

 

[EFLImpudence]

What is 'mere touching' other than brief 'holding? (electricity moves quite fast!)

It is the not being able to let go which is important.

What about if it developed an L-E fault of sufficiently high resistance (water?) for an OPD not to operate, but low enough impedance to be a problem if an 'earthed' person (e.g. standing on ground with bare feet) were to touch an exposed-c-p.

Then you would be in the thinking it desirable camp despite your views on it happening.

Sure, but we have to accept that a lot of people believe that - and we also have to accept that sooner or later (even if it hasn't yet happened, which it probably has now and again) RCDs will save at least a few lives.

I can't argue with the theory but it is for some reason not a requirement.

 

[JohnW2]

It is the not being able to let go which is important.

That can certainly make it worse, but I think you may underestimate how rapidly a shock can (sometimes) be fatal. In any event, a person could be holding the light (e.g. whilst changing a lamp/bulb).

Then you would be in the thinking it desirable camp despite your views on it happening.

. Not really - I was representing the possible views of those in that camp.

I can't argue with the theory but it is for some reason not a requirement.

As I said at the start (and repeated in my last post), I acknowledge that it is not a requirement. In any event, whatever my personal feelings, I suspect that we may only be one or two Amendments (or, at least, one edition of the regs) away from the day when virtually everything will be required to have RCD protection - we've been gradually approaching that situation.

Kind Regards, John

 

[EFLImpudence]

That can certainly make it worse, but I think you may underestimate how rapidly a shock can (sometimes) be fatal. In any event, a person could be holding the light (e.g. whilst changing a lamp/bulb).

No, but it is a question of lengths to go to protect people.
If the barefoot non-isolating DIYer is the target then presumably everything should have an RCD.

. Not really - I was representing the possible views of those in that camp.

Why?

As I said at the start (and repeated in my last post), I acknowledge that it is not a requirement.

I know. Therefore it cannot have been considered important.

In any event, whatever my personal feelings, I suspect that we may only be one or two Amendments (or, at least, one edition of the regs) away from the day when virtually everything will be required to have RCD protection - we've been gradually approaching that situation.

Do you think there is a good reason for this (other than above B,N-I DIYer)?

If not, in view of the numbers, what is the reason?
Bearing in mind that manufacturers and new cables and sockets call for RCD protection and replacement CUs will likely have RCD on every circuit, will it make any difference?

 

[JohnW2]

No, but it is a question of lengths to go to protect people. If the barefoot non-isolating DIYer is the target then presumably everything should have an RCD.

Yes, that is the question - and the answer is very much open to debate. However, particularly once one gets outside of the building, I suppose it's not just the "barefoot non-isolating DIYer" one has to consider. There is also, for example, his innocent non-DIYing daughter with bare wet feet!

. Not really - I was representing the possible views of those in that camp.

Why?

That should be apparent from the evolution and chronology of this discussion. I suggested that "there is an argument (not necessarily subscribed to by myself) for RCD protection (of outdoor circuits) being desirable". When you probed me about that, I indicated what one basis of such an argument could be (effectively on behalf of those who subscribe to that view).

In any event, whatever my personal feelings, I suspect that we may only be one or two Amendments (or, at least, one edition of the regs) away from the day when virtually everything will be required to have RCD protection - we've been gradually approaching that situation.

Do you think there is a good reason for this (other than above B,N-I DIYer)? If not, in view of the numbers, what is the reason?

You tell me. Emotions, knee-jerks, politics, fear of public opinion and lack of (and/or flawed interpretation of) statistical information all come to mind. It obviously cannot be to produce a substantial reduction in domestic electrocutions - there are so few already (a good few of which could not be prevented by an RCD), that even the complete banning of electricity could not reduce absolute the number of domestic electrocution by more than a small handful per year.

Bearing in mind that manufacturers and new cables and sockets call for RCD protection and replacement CUs will likely have RCD on every circuit, will it make any difference?

Exactly - that's my point. We're almost there already, so they might as well (and, IMO, probably will) introduce a 'blanket' requirement. At least there would then not be any uncertainties or scope for debates/ discussions such as you and I are having!

Kind Regards, John

 

[bernardgreen]

No, but it is a question of lengths to go to protect people.

Cost of compliance also affects the extent of regulations. Making compliance expensive ( cost of RCBO on every circuit ) means people will avoid being compliant and thus avoid reading the rules and doing that which is essential.

If the barefoot non-isolating DIYer is the target then presumably everything should have an RCD.

And the DIYer with one ungloved hand gripping a metal ladder..

There is also the average person changing the lamp bulb un-aware that the lamp is switched ON ( the lamp is dark ) using a metal ladder on wet ground. The electric shock from the faulty lamp may not be fatal but the fall of the ladder may be fatal or result in life changing injuries.

An RCD would not prevent the non fatal shock from a faulty double insulated non earthed lamp fitting. But it would if the metal case of the lamp fitting was earthed as the RCD would trip as soon as the fault occurred and long before the person got to touch the lamp fitting.