Maximum Length Flex For T5 Link Lights

[Ripperoo]

Hey Guys

I am thinking about having some fluorescent under-cupboard link lights installed around my kitchen, but need a bit of advice as the cupboards are a bit spread out.

What is the maximum length of 0.75mm 2-core that can be used?

If you look at the diagram below, you can see the lower-right cupboard is approx 7 metres away from the power supply (only one available) when taking into account the drop from ceiling.


Click Image To Enlarge

Also, is it OK to run 0.75mm 2-core through the void behind 100mm plaster ceiling coving?

 

[securespark]

Interesting question bearing in mind the big debate that was had a while back on whether cables should be run with a cpc.

 

[Iggifer]

you don't need to run the cable 7m though?

You only need to run it from the previous light to the next?

Which looks like, at most, 1m away?

The maximum run of 0.75m would depend on the current you need for the last lamp, but 0.75mm is good for ~6a you should be fine.

Is there insulation in the ceiling void or is it empty?

 

[Iggifer]

Interesting question bearing in mind the big debate that was had a while back on whether cables should be run with a cpc.

quite, do it in 1.0mm T+E, save the arguments

 

[Ripperoo]

Interesting question bearing in mind the big debate that was had a while back on whether cables should be run with a cpc.

Thanks for the quick replies guys, but what is a 'CPC'?

 

[Ripperoo]

You only need to run it from the previous light to the next? Which looks like, at most, 1m away?

Can't do that though as there is a window in between the upper-right and lower-right cupboards. So the only way the cable could be run is through the coving, if that is acceptable as there is no mains outlets at that end of the kitchen.

The diagram was maybe a little too basic I suppose.

The 7 metres I mentioned is as the cable will possibly run. I've just quickly measured it and it's actually 7.5m.

The maximum run of 0.75m would depend on the current you need for the last lamp, but 0.75mm is good for ~6a you should be fine.

The lamp furthest away from the power supply (lower-right) is 10w, so will that be OK?

In fact all four lights total 62w (6w + 10w + 16w +30w)

Is there insulation in the ceiling void or is it empty?

Above the kitchen is a bedroom with no insulation between the floors, if that's what you mean.

 

[Ripperoo]

Interesting question bearing in mind the big debate that was had a while back on whether cables should be run with a cpc.

Thanks for the quick replies guys, but what is a 'CPC'?

Earth?

 

[bernardgreen]

CPC = Circuit Protective Conductor.

It is the wire known as the earth wire.

 

[sparkwright]

As mentioned earlier, the correct way would be to run a 1.0 mm2 twin and earth cable from the 'power supply' to the far cupboard.

Join this and your light lead together, either using a 20 amp junction box, or a pattress and blanking plate with 5 amp connector blocks. Do not cut off the bare earth wire. Sleeve it with green and yellow sleeving, and connect it to a spare terminal.

 

[Ripperoo]

As mentioned earlier, the correct way would be to run a 1.0 mm2 twin and earth cable from the 'power supply' to the far cupboard.

Join this and your light lead together, either using a 20 amp junction box, or a pattress and blanking plate with 5 amp connector blocks. Do not cut off the bare earth wire. Sleeve it with green and yellow sleeving, and connect it to a spare terminal.

OK, great stuff.

I should have mentioned that the 'Power Supply' shown in the pic in the First Post, is a 2G 13a switched socket.

Does that have any bearing on what has been suggested?

Thanks

 

[sparkwright]

It has a bearing on the whole project.

If it's fed from a socket, it needs a 13 amp fused spur (5 amp fuse fitted) connection unit, You can't wire the lights directly to the back of the socket.

OR

Do you mean you are simply fitting a plug onto the lead, and plugging into the socket.

 

[Ripperoo]

It has a bearing on the whole project.

If it's fed from a socket, it needs a 13 amp fused spur (5 amp fuse fitted) connection unit, You can't wire the lights directly to the back of the socket.

Could a regular 3-pin plug not be used (fitted with a 5 amp fuse)?

 

[Ripperoo]

Do you mean you are simply fitting a plug onto the lead, and plugging into the socket.

You beat me to it!

 

[sparkwright]

If you're plugging it in, simply use 1.0 mm2 3 core flex (not twin and earth as I previously suggested).

Connect the earth core to the earth terminal of the plug.

At the other end (light end) terminate the earth core in a spare terminal.

Use a 5 amp fuse in the plugs.

 

[Ripperoo]

One more thing I will add is that the 2 gang 13a socket will come straight from the CU via 16a MCB + 2.5t&e (radial circuit?). It will also be the only outlet on that circuit.

This 2 gang socket will be installed with the intention of also using it with a small cooker hood if that is acceptable.