Grid Switch Questions

[dunny123]

I am installing an 8 gang grid switch in a kitchen, never fitted one before. Its supplied via a 32A RFC in 2.5 T&E. The loads will be Dishwasher, Hob Ign, Ext Fan and Under Cabinet Lights. The design is 4 DP switches below 4 fuse units, (13A for D/W, 3A for rest)

First question:
Do you bring the ring into a chock block inside, or use the first DP switch as the termination, meaning 3 x 2.5mm cables in L&N (2 for the ring and 1 out to next switch in the grid), they do fit but the switch terminals seem a bit weedy for this, even though its a 20A DP.

Second Question:
The kitchen will be tiled eventually, which will mean the yokes will sit too far back for the grid cover. Will the yokes need to sit against the front surface of the tiles, or will I need to pull forward the backbox to be flush with the face of the tiles ? Hope you understand what I mean.

 

[RF Lighting]

First question:
Do you bring the ring into a chock block inside, or use the first DP switch as the termination, meaning 3 x 2.5mm cables in L&N (2 for the ring and 1 out to next switch in the grid), they do fit but the switch terminals seem a bit weedy for this, even though its a 20A DP.

You should take 1 leg of the ring to the first switch, and the other leg to the last switch. You then link from sw1 > sw2 > sw3 > sw4.
This will result in you having two wires in each switch, and all the accesories will remain on the ring.

Second Question:
The kitchen will be tiled eventually, which will mean the yokes will sit too far back for the grid cover. Will the yokes need to sit against the front surface of the tiles, or will I need to pull forward the backbox to be flush with the face of the tiles ? Hope you understand what I mean.

The yokes will need to sit flush with the tiled surface as if it would with a normal plastered wall.

If the screws in the yoke are not long enough to allow this, you can extend them with castle studs, or cut the screws out of the yoke, and fit normal long socket screws.

 

[dunny123]

You should take 1 leg of the ring to the first switch, and the other leg to the last switch. You then link from sw1 > sw2 > sw3 > sw4.
This will result in you having two wires in each switch, and all the accesories will remain on the ring.

Thanks RF, I had considered this, but felt may introduce more potential of a break in the ring being as the ring itself having several connections within the grid. However, as you say this means all accessories are on the ring, rather than spurs, so good call.

The yokes will need to sit flush with the tiled surface as if it would with a normal plastered wall.

I think my problem is the mounting box I have used is designed for surface mount, because the yokes sit inside the box. But I assume I can overcome this by creating an aperture with the tiles that leaves the yoke lugs in front of the tiles, and as you say long pins to reach the box behind.

 

[RF Lighting]

Connecting the four switches on the ring is no different to having four sockets connected on a ring, and should be no more likely to introduce a fault either.

Even in the unlikely event of ending up with an open circuit ring for example, anything like this will be shown when you test the installation prior to commisioning it.

 

[dunny123]

I agree that that the wiring in no different than four sockets on a ring, I was alluding to the size, rating and integrity of the terminals in the switches. It would be obvious during testing if there were an o/c orpoor connections, I was thinking further down the line when they've been installed for some time, and maybe disturbed during tiling, decorating or the like.

On the mounting box question, is the outside dimension of the flush box smaller than the surface box ?

 

[RF Lighting]

Yes.

The grid plate will be the same size as a surface mount box. It will be about 7mm larger on each edge than a flush box.

 

[dunny123]

Thanks RF for your replies.