FCU connected to ring main

[masona]

Many thanks lads, always learning

So in theory the 20A double pole switch should never see more than 20A across its contacts on the ring main?

Just seen a 32A double pole switch, wouldn't this be better?

 

[bernardgreen]

I would suspect that as it would be in the ring, the restriction is on the rating of the input terminals

That can't be it because it's exactly the same on a radial and would only be 13A maximum - unlike a double socket.

The inportant parameter is the maximum current that can flow from cable to cable where they are clamped together in the terminal. This must be greater than the rating of the MCB protecting the circuit. Strangely I have only ever seen it quoted on data sheets for industrial sockets.

 

[AndyPRK]

Many thanks lads, always learning

Just seen a 32A double pole switch, wouldn't this be better?

No, be too clunky.

They make FCU's engraved washing machine etc for just this reason.

Use one of them.

http://www.ebay.co.uk/itm/CRABTREE-...al_Electrical_Fittings_MJ&hash=item4d0aeed5e3

 

[phatboy]

I expect you would connect a 2.5mm t+e on the load side of the switch. If there was a fault in this cable, the contacts on the 20amp switch could overheat before the MCB trips.

Using an FCU means that there will be the safety of a 13amp fuse to blow instead.

Also, someone down the line could replace the single socket below the counter with a double and connect 2 high current devices. This would overload the switch. Having a FCU prevents this, and means someone would have to consciously change out the FCU to achieve what they wanted

 

[masona]

Using an FCU means that there will be the safety of a 13amp fuse to blow instead.

This is what I have decided to do and have now connected and run the 2.5mm² T&E spur to a single socket under the worktop.

Now because of this I would like to run a spur from the single socket to another socket for a freezer, is this acceptable unless 1 spur is enough for the washing machine ? The T&E cable is about 1m from the FCU to the socket but will be another 2m run if I spur from there.

Won't be a problem because I can do it another way

 

[phatboy]

Hopefully you used an un-switched socket under the worktop? Saves accidental switch-offs when pushing the appliance back in.

You could run another socket from this one for your freezer, but I wouldn't recommend it, it may be enough to blow the 13a fuse.

 

[EFLImpudence]

I expect you would connect a 2.5mm t+e on the load side of the switch. If there was a fault in this cable, the contacts on the 20amp switch could overheat before the MCB trips.

Perhaps better not to fit one, then?

Using an FCU means that there will be the safety of a 13amp fuse to blow instead.

True, but unnecessary and only protecting that which need not be there..

Also, someone down the line could replace the single socket below the counter with a double and connect 2 high current devices.

That wouldn't matter to the cable.
You could say that was the fault of installing an unnecessary FCU when all would be well had the spur been run from the existing socket.

This would overload the switch. Having a FCU prevents this, and means someone would have to consciously change out the FCU to achieve what they wanted

You mean replace it with the original socket.

 

[AndyPRK]

One FCU per appliance is normally the way its done.

And you can turn off the W/M when its not being used.

 

[phatboy]

I expect you would connect a 2.5mm t+e on the load side of the switch. If there was a fault in this cable, the contacts on the 20amp switch could overheat before the MCB trips.

Perhaps better not to fit one, then?

Using an FCU means that there will be the safety of a 13amp fuse to blow instead.

True, but unnecessary and only protecting that which need not be there..

Also, someone down the line could replace the single socket below the counter with a double and connect 2 high current devices.

That wouldn't matter to the cable.
You could say that was the fault of installing an unnecessary FCU when all would be well had the spur been run from the existing socket.

This would overload the switch. Having a FCU prevents this, and means someone would have to consciously change out the FCU to achieve what they wanted

You mean replace it with the original socket.

Whats your point then? Whats your suggestion for a solution?

 

[EFLImpudence]

If the OP wants a switch, for whatever purpose, then, apparently, he will have to fit an FCU.

It's just that you seemed to be thinking of every unlikely scenario when it may be advantageous to have the fuse when these occurrences are are only disadvantageous because the FCU is there - because the OP wants a switch.

 

[masona]

Hopefully you used an un-switched socket under the worktop? Saves accidental switch-offs when pushing the appliance back in.

No I didn't as the socket is in the next base unit and not in the washing machine area as I didn't want any water leaking near it

You could run another socket from this one for your freezer, but I wouldn't recommend it, it may be enough to blow the 13a fuse.

It's not problem as I can run a cable from using the 16 amps radial

 

[Bluehair]

Is the reason I've listed why?

I mean, would a 32A switch be compliant?

Regulation 433.1.5 only lists BS1363 devices as being acceptable to be supplied from a RFC, and AFAIK this standard only applies to 13A socket outlets, and FCUs.

The word "only" is not used in 433.1.5. It says that BS1363 MAY be supplied with or without unfused spurs and does not preclude the use of a 20A switch to supply an unfused spur.