Grid switches on 32A ring

[Deleted member 112675]

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.

Thanks for that but the feed in surely has to continue the ring thus would need two cores per terminal? (And the load side as you say off to the socket). So each DP switch controls a single spur with a single socket.

 

[Midwest]

Thanks for that but the feed in surely has to continue the ring thus would need two cores per terminal? (And the load side as you say off to the socket). So each DP switch controls a single spur with a single socket.

Yep, as said feed in and feed out per terminal. And each DP switch feeds an appliance via a single cable. We at cross purposes?

 

[Deleted member 112675]

Yep, as said feed in and feed out per terminal. And each DP switch feeds an appliance via a single cable. We at cross purposes?

Sorry yes might be my fault - I had to change my original post.
So if there is feed in and feed out that could easily go beyond 13a (and possibly beyond 20a depending on where it is in the ring?). Not sure if its an issue in practice though?

ANd in any case no more than 13a would be going through the switch.

 

[Strima]

So if there is feed in and feed out that could easily go beyond 13a (and possibly beyond 20a depending on where it is in the ring?).

Both cables will be in the same terminal and clamped together so the current is flowing through the cables and not the terminal block.

Most switches would normally feed a single socket for an appliance however you could potentially use a double socket-outlet for two appliances, these are normally rated for a maximum of 20 amps hence the 20 amp rating on the switches.

This is down to diversity of the loads and unless you have two three bar heaters plugged in it's doubtful you'll ever exceed 20 amps on a switch.

 

[telectrix]

might never exceed 20A through the switch but why do i keep finding them burnt out and occasionally bridged? spawn of the devil, would never fit myself.

 

[Taylortwocities]

might never exceed 20A through the switch but why do i keep finding them burnt out and occasionally bridged? spawn of the devil, would never fit myself.

They burn out because they’ve been installed badly, often by fitters of kitchens. And I agree, pain in the whotsit, and mostly pointless.

 

[Midwest]

might never exceed 20A through the switch but why do i keep finding them burnt out and occasionally bridged? spawn of the devil, would never fit myself.

There's thousands out their with no problems. Perhaps those that have caused issues are like problems RFC's have, to the unanitiaive. (cant be arsed to spell it correctly)

 

[Oliver Luke Martin]

Sorry all to revive an old post. I’ve often thought 20A switches are underrated so was looking for alternative. I’m installing a grid switch to feed appliances in the customers house. I’m using Scolmore Minigrid 32A switches, this allows full current through the RFC without worrying about terminals over heating. What are your views on this solution?

 

[Taylortwocities]

Don’t see the problem. A grid switch isolating a single appliance should never have to handle more than 13A. Unless you have a double socket, even then the expected load shouldn’t exceed 20A.

. I’m using Scolmore Minigrid 32A switches, this allows full current through the RFC

But you should never be interrupting the ring final. That’s the only place where the higher current might be found. Even then it’ll be around 20A max.
The switch will only ever see the current on the (switched) spur.

 

[Oliver Luke Martin]

Incase I wasn’t clear the 32A switch allows the RFC to continue at a potential full load on the supply as the terminals are rated at 32A as a pose to 20A on many grid switches. Only one socket/appliance on the load side.

 

[Strima]

Incase I wasn’t clear the 32A switch allows the RFC to continue at a potential full load on the supply as the terminals are rated at 32A as a pose to 20A on many grid switches. Only one socket/appliance on the load side.

The switch is rated at 20 amps not the supply side terminals which are designed for much higher currents.

 

[ackbarthestar]

I thought a 20A DP switch was rated at 20A. Please point me in the directions of the specifications for a 20A DP switch where the input terminals are something else

 

[Avo Mk8]

Looking at the specifications of MK 20A grid switches, they quote the input terminal capacity as 3 x 2.5mm or 2 x 4mm or 1 x 6mm. The MK 32A cooker switch has the same input terminal capacity figures. I don't see any MK specification for the maximum through current between two conductors stuffed in the same input terminal, but I suspect from the above is that it would be more that the rating of either of those switches.

 

[Dartlec]

Sorry all to revive an old post. I’ve often thought 20A switches are underrated so was looking for alternative. I’m installing a grid switch to feed appliances in the customers house. I’m using Scolmore Minigrid 32A switches, this allows full current through the RFC without worrying about terminals over heating. What are your views on this solution?

I suspect the terminals on any switch are probably not the limiting factor, it's the connections within the switch that may be. I see their 32A switches are double width, so the extra space may allow for meatier internals and a higher rating on the throughput. They also do a 20A DP switch of the same size though, so maybe it's mostly marketing. Would be interesting to take one of each apart and see what the difference is.

The terminals on all but the cheapest accessories could probably easily cope with 32A for straight in and out connections. Sockets are mostly rated at 20A after all but still are fine on a ring - whenever I've seen overheat damage it's usually due to loose connections, and it's the plastic that gives up not the terminal.

Having said that, I have started using the minigid light switches a lot recently, and they seem pretty well made so seems like a neat solution to provide isolation of under worktop appliances.

 

[Strima]

I thought a 20A DP switch was rated at 20A. Please point me in the directions of the specifications for a 20A DP switch where the input terminals are something else

TBH I could have worded my response a little better. The supply side terminals don't have to be load rated as such due to the fact they clamp conductors together and take no load themselves.