12v cabling regs ?

[vinny8]

Hello, 12 v cabling. In a false ceiling, does`it have to comply with Regs as per 230v. ie spacing of cable clips etc. replies much apreciated thanks.

 

[breezer]

cables for what, current determines size of cables, not voltage

 

[vinny8]

Cheers, ELV cables in this case`12 volt. From Transformer to appliance.

 

[Big_Spark]

There is nothing specific you need to be concerned about, so long as the cable meets BASEC requirements, BS compliant and is sized accordingly to the load it will be subjected too.

Remember that current at 12V will be a lot higher than 230V

Example

230V 50W Halogen Dichroic lamp draws 0.21A from the supply

12V 50W Halogen Dichroic lamp draws 4.166A from the supply, thus is will need a larger cable size than 230V lamps.

 

[ban-all-sheds]

Hello, 12 v cabling. In a false ceiling, does`it have to comply with Regs as per 230v. ie spacing of cable clips etc. replies much apreciated thanks.

The regs on cable supports are based on physical size, so the answer to your question is an unequivocal "yes".

 

[vinny8]

FWL........... Thanks i fully understand your info there thats very helpful. i am using 2 core 6amp lighting cable. Ban thanks as well . is a yes a yes or a yes. I take it the cables need clipping up at the same distances as others. 200mm i understand.

 

[ban-all-sheds]

FWL........... Thanks i fully understand your info there thats very helpful. i am using 2 core 6amp lighting cable.

What do you mean by that? 1.0 or 1.5mm² twin & earth?

What is the lighting load on each cable, and how long is the cable? have you checked that it's OK for voltage drop?

Ban thanks as well . is a yes a yes or a yes. I take it the cables need clipping up at the same distances as others. 200mm i understand.

250mm is the maximum, but a smaller gap is good.

 

[Big_Spark]

For LV downlighters it is usual to use 2.5mm two core flex that is specifically manufactured for use on ELV, SELV and PELV circuits, however if you are able to obtain 2.5mm butyl rubber flex this will do the job.

Twin and Earth cable should not be used for supplying 12V lights.

 

[ban-all-sheds]

Twin and Earth cable should not be used for supplying 12V lights.

Why not?

 

[plugwash]

there are two issues i can think of

one is you either risk introducing an earth to a seperated cuircuit or you leave an "earth" wire floating or your use an earth wire for something other than earth none of which are good practice

the other is possiblly heat resistance depending on the design of the individual lights.

 

[ban-all-sheds]

OK

 

[Big_Spark]

Plug has hit the two of the reasons on the head, but there is also the fact that T&E would leave people thinking that these may be 230V supply cables when they are not, by using the correct cable, you clearly identify the feeds as ELV,PELV or SELV not plain LV.

Segregation of circuits is more than simply not mixing cables, it is also about clearly identifying cables too.

 

[vinny8]

Tis great help thanks. I had .75mm 2 core flex no earth but i noted that 2.5mm is mentioned by FWL. the length of csbles from Tranformer to light is about 500mm. i have 35watt 12v dichroic lights. i assume the amperage is just over 3a. the .75mm 2 core cable appears to small although it is rated for 6a lighting circuits.

Chaps your info is invaluable thanks

 

[ban-all-sheds]

0.75mm² is good for up to 2.5m for a 35W lamp.

http://www.tlc-direct.co.uk/Technical/Lighting/VoltageDrop.html

 

[NealHarman]

Twin and Earth cable should not be used for supplying 12V lights.

B****r, B****r, B****r How massive a sin is this? (Before I stick the ceiling up tonight using the tower I've got hired until tomorrow?)

Neal