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Discuss Grid switches on 32A ring in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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I've been trying to work out whether grid switches (ie. a 20A switch) are acceptable on a normal 32A ring. I've read many threads online. Very few people seem sure whether it's acceptable but many sparks seem to do it in kitchens etc.

The argument seems to be that the switch is rated at 20A but there could be 32A flowing through the ring. However, how much of that 32A would actually go through the terminal? The majority of the current would go straight from one wire and into the other as they will be touching. I can't see it being an issue but the real question is whether it meets regs. Does anybody have the official answer to this?
 
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Andy78

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Have a read up on the regs surrounding ring final circuits with the start off point being that 2.5mm cable clipped direct is only rated for 27A.
Also think about how the 20A DP switch is to be connected into the circuit and the load that would be drawn through it.
 
T

Toneyz

If a bank of grid switches supplying a few high current used appliances this should be located as close as practically possible to the midpoint of the kitchen ring final circuit.
 

Taylortwocities

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Your grid switch will be on a spur (LOAD) output from a ring

So that will not be 32A, will it? The only place where it might be anything near 32A is at the MCB in the CU.
 

ChrisElectrical88

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The load across the switch will be 13A maximum as you would imagine that they feed a single socket or spur each.

However i am not a fan of them and have been called out to a few crackling due to poor termination. Takes a lot of care and a 47mm backbox to get them perfect, something not many people do.
 
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Have a read up on the regs surrounding ring final circuits with the start off point being that 2.5mm cable clipped direct is only rated for 27A.
Also think about how the 20A DP switch is to be connected into the circuit and the load that would be drawn through it.
That all makes sense now. This is what I had originally though but my mind had been led astray by some convincing replies I had read.
 

telectrix

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grid switches...spawn of the devil. rated at 20A yet burn out on 13A max. .... need to knock a brick out to get all the cables in. never can get the faceplate on right.... and the 1 marked fridge controls the dishwasher.
 
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However i am not a fan of them and have been called out to a few crackling due to poor termination. Takes a lot of care and a 47mm backbox to get them perfect, something not many people do.
This is my biggest fear. However, they look great when they are done well and will take up a lot less space in my small kitchen.
 
Me personally not a big fan of grid logic switches

But if done correct do serve a purpose

but as telexctric mentions the amount of wonky badly installed ones is frightening , and never assume they are wired correct

turn off the one marked fan and you probably just isolated the washing machine
 

Taylortwocities

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I really do not like a bank of grid switches fed from a ring final. The whole point of a ring final is to distribute the loads round the ring. With a grid bank you’ve got all of the high power items coming from a single point on the ring.

If you MUST have a mission control panel like this, then it is best fed from a 32A 4mm radial. That finishes the sermon on the mount for today.
 
I am not a fan of this method. The last few firms that I have worked for do this method, even having a fuse holder in the grid switch along with the socket by the appliance, so having 2 fuses in series and making it more fiddly, along with them mounted in a cupboard. Also as has been said before they are fiddly and prone to issues. Especially when under pressure to get jobs done as quickly as possible.
 

Midwest

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I think the only reason these are used in new builds, is to comply with Part M, with all the sockets for appliances in cupboards or behind appliances.
 
Your grid switch will be on a spur (LOAD) output from a ring

So that will not be 32A, will it? The only place where it might be anything near 32A is at the MCB in the CU.
I know this is a few months old but I found it quite an interesting thread.

Presumably each switch is on a spur and doesn't that mean the supply side of each switch module will have 2xL and 2xN cores - continuing the ring in and out.

So there could be more than 13a flowing through the terminals on the supply side of the switch. But maybe that's ok because its not flowing through the switch ?

EDIT CORRECTION: Apologies I corrected this a couple of times !
 

Midwest

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Don’t think so. Each DP switch will have feed in and a feed out, for each live & neutral terminal, thus completing the RFC. The load side of the switch will feed the appliance.
 
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