Providing garage with power supply from external plug on house

[JohnW2]

I think 20A switches are more expensive than an FCU though.

Probably true. However, the 'rating' of a switch usually relates to the maximum current it might be called upon to break, so I'd be perfectly happy to have lights supplied by a '6A' switch (and 'protected' by a 13A fuse). Under what circumstances could the switch be called upon to break more than 6A?

In the case of a fault downstream of the switch, a fault current of probably several hundred amps would flow (until some OPD operated) - but if a current of 'several hundred amps' is flowing through the switch for a very brief period of time, it hardly matters whether it is 'rated' at 6A or 20A!

Kind Regards, John

 

[AndyPRK]

One may end up with contacts welded together.

 

[Iggifer]

MK standard switches are rated at 10A so that's marginally better than 6A, and they're only £1 each, and MK 20A switches are cheaper than their 13A FCU's, obviously other brands may vary, and MK are generally quite expensive anyway

 

[JohnW2]

One may end up with contacts welded together.

In the case of a fault current of several hundred amps, you mean? If so, yes, that's a possibility - but, as I said, not really any more likely with a '6A rated' switch than with a '20A rated' one (or even, come to that, a '50A rated' one).

As for an overload (as opposed to fault) current in excess of, say, 6A, as I implied, I just don't see how a light or light fitting could result in that, can you?

Kind Regards, John

 

[JohnW2]

MK standard switches are rated at 10A so that's marginally better than 6A, and they're only £1 each, and MK 20A switches are cheaper than their 13A FCU's, obviously other brands may vary, and MK are generally quite expensive anyway

Fair enough, but as I keep saying/asking, what is the perceived problem with a switch supplying just a a light having a 'rating' of 'only 6A' (or 10A) when it's protected by a 13A fuse ?

Kind Regards, John

 

[Iggifer]

I suppose it's down to following the MI's. If there's no max current specified, nobody can really argue, but if they say 6A max, and there is a problem, it's gonna come back and bite you (not so much the case for a DIYer though I guess)

 

[JohnW2]

I suppose it's down to following the MI's. If there's no max current specified, nobody can really argue, but if they say 6A max, and there is a problem, it's gonna come back and bite you (not so much the case for a DIYer though I guess)

If they say what is "6A max"? It presumably refers either to maximum breaking current or the maximum current that may pass through the switch. In either case, I just don't see how a light/fitting can result in a current remotely as high as 6A, regardless of what OPD may be protecting the circuit - can you? As I've said, fault currents are a totally different kettle of fish, and are going to be dozens of times higher than the 'rating' of any switch you would seriously contemplate installing for a light!

Kind Regards, John

 

[Iggifer]

I suppose it's down to following the MI's. If there's no max current specified, nobody can really argue, but if they say 6A max, and there is a problem, it's gonna come back and bite you (not so much the case for a DIYer though I guess)

If they say what is "6A max"? It presumably refers either to maximum breaking current or the maximum current that may pass through the switch. In either case, I just don't see how a light/fitting can result in a current remotely as high as 6A, regardless of what OPD may be protecting the circuit - can you? As I've said, fault currents are a totally different kettle of fish, and are going to be dozens of times higher than the 'rating' of any switch you would seriously contemplate installing for a light!

All true. I suppose it depends if there's going to be a hydroponic set up in the garage! I'm sure you'd soon get there!