10a under counter switch

[thefuzz247]

Ive purchased a 10a under counter "wedge style" switch from tlc with the intention of using it to switch 4 x20w lv halogen under counter lights.

I was proposing to take a spur from the ring main to a fsu (with 5 amp fuse) and then from the fsu onto the lv lighting with the aim of the lights being switched by the 10a undercounter switch. Two questions:

1. Does the switch operate after the transformer on the 12v circuit or before it on the 230v?
2. The switch itself only has two terminals labelled in and out so how should the switch be connected? (I was originally assuming there would be a live and a neutral in the switch housing - aka like a "normal" light switch that I could then run to a ceiling rose type device to which the transformer is connected?)

With these questions in mind can anybody enlighten me with the correct wiring diagram?

Thanks in advance for any words of wisdom.

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Sorry - by under counter I obviously? meant under wall unit! Doh!

__________________________________
moderator

please note 10a

 

[Adam_151]

switch on the 230v side of the transformer.

Take a spur from a s/o on the ring using 2.5mm² cable to the supply terminals of the fcu, fit a 3amp fuse in it, use 1.5mm² cable to the switch, connect live to com, neutral to a terminal block, another 1.5mm² cable from the switch ot a flex outlet plate or something, connect live to l1 in the switch, and nutral to the other side of the terminal block, terminate both earths in the brass earthing point on the box, ensure earth continuity at all other acesories as well

 

[Spark123]

1. Does the switch operate after the transformer on the 12v circuit or before it on the 230v?

On the 230v side.

2. The switch itself only has two terminals labelled in and out so how should the switch be connected? (I was originally assuming there would be a live and a neutral in the switch housing - aka like a "normal" light switch that I could then run to a ceiling rose type device to which the transformer is connected?)

There is not normally a neutral in a light switch, you may be thinking of the 20A double pole switches used for such things as storage or immersion heaters.
You can connect the supply from the FSU live to in, transformer live to out, link both neutrals together in a piece of terminal block, connect the supply earth to the back box and to the transformer earth if the transformer is not double insulated.

Another option you may consider is to purchase a switched fused spur unit, you can wire the transformer directly to this.

 

[thefuzz247]

Thanks very much for the posts - I now understand the correct way to proceed.

Just one question regarding the earth?.....The 10a switch has a small black plastic switch housing that contains the in and out terminals (read live and switched live if I understand the posts correctly) but there doesnt seem to be a dedicated earth terminal in the switch housing itself?

However the actual outer casing of the wedge switch is made of metal and it does have an integral inner metal "tab" with a small hole in it. Should this be where the earths are connected from the supply and the transfomer (if not double insulated)? ie the switch outer casing (that you can touch) becomes the earth?

Thanks once again for all the insightful advice. Much appreciated.

 

[Spark123]

If the transformer is not double insulated it should have an earth wire in the cable. (Double insulated is usually shown on the item as a square in a square). I would terminate earth wire from the mains into a terminal block, terminate the transformer earth into this and loop a single piece of wire from the terminal block to the back box earth as some back box earths are not brilliant.
The metal back box is very unlikely to be double insulated, you may have got away with a plastic back box.
The small hole in the tab you refer to may once have had the earth screw in (fallen out?)

 

[thefuzz247]

Can I just join the earths of the transformer and supply together then - and thus ultimately back to the eath terminal in the fsu box? - i.e. the switch is not earthed at all as it is made of metal?

Sorry if im being thick but the switch does not have a back box to which an earth terminal is connected. It is basically a wedge shaped sheet of metal surrounding a black plastic connection block with a rocker switch. The wedge shaped sheet of metal is simply screwed to the underside of the cabinet - ive just realised this is of course what the hole I described is for!

Thanks once again sparks123. You're a star!

 

[Adam_151]

Is there any earthing point on the metal surround of the switch, there should be, as it requires earthing

 

[thefuzz247]

The only possibility I can see for attaching the earth is to the screw fixing holder (to the cabinet underside) which is an integral metal tab that is part of the inside of the metal switch casing, or to the fixing srews that secure the black plastic switch connector (in and out) insert to the outer metal casing? If that makes sense?

 

[plugwash]

i'd stick a crimp eyelet on the earths then and put it over the fixing screw to the counter not ideal but its probablly the only feasible way to earth it.

 

[Steve]

or solder it on . . .

 

[Spark123]

Is this the switch?
http://www.tlc-direct.co.uk/Main_In...essories/Wall_Switches_White_4_Arc/index.html

 

[thefuzz247]

Thankyou to everyone for the comprehensive advice - I feel much happier now

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This is the actual switch - thanks sparks123 - I didnt think of posting the link!

http://www.tlc-direct.co.uk/Products/KS106.html

___________________________________

moderator

you also do not seem to read your own posts.

please note 10a

 

[securespark]

If the switch has the afore-mentioned double insulated symbol on it, then it does not require an earth connection.

If it doesn't, ring the mfr.

 

[thefuzz247]

If the switch has the afore-mentioned double insulated symbol on it, then it does not require an earth connection.

If it doesn't, ring the mfr.

I spoke to the supplier who said it was a "continental" type switch and does not therefore need an earth? Because the switch is plastic. It doesnt have the square in square symbol on it though.

He also commented on the proposal to connect earth through the fixing screw to the cabinetas being ok as well?

So can anyone tell me which is the best way to go?

 

[securespark]

If it doesn't, ring the mfr.