12v Bathroom Downlights - Too Much for the Cable

[gaz0001]

Hi,

I think i may be trouble in terms of the Current and my lights, but really need a sparks advice to confirm.

I have 8, 50w Bathroom Downlights. 400w in total. (I know, the bathroom has no window!)

Each light has its own 12v transformer, so i planned to loop in loop out to all the transformers, providing mains to them all in series.

I know that the current is increased when the voltage is decreased, but im not sure whether this increased current will only be present on the small 12v cable from the transformer to the fitting or on the 240v T&E cable??

I think its just on the cable between the transformer and the light fitting and since each transformer has its own cable to the fitting then i should be ok.

Just need this confirming please.

 

[Spark123]

You don't really mean series
Not taking into account transformer losses, the current on the mains side will be roughly 400/240 = 1.67 A.
The current between each transformer and each lamp is 50/12 = 4.17A.
I take it you know this work is notifiable to your LABC under Part P of the building regs.

 

[gaz0001]

Hi Spark123,

I was not aware that it was notifiable. I thought that i could change a light myself???

Is this not the case??

The house is mine, there is no flat or anything above it and i have full access to the loft. There is already a light there with switch. All i need to do is move the ceiling rose into the attic and replicate it there, mount all the transformers to a board, daisy chain them to the mains and run cables to the 8 spots.

Do i need a legally need a spark to do this?? If so then thats what ill do.

 

[NewOrder]

As I understand it installing low voltage lighting is notiable as transformers draw more current and the existing circuit may become overloaded. There is also the issue with heat.

The thing is I believe replacing fittings in the bathroom other than like for like is also notifiable as its a special location. You don't need a spark to this, but you do need to pay the council to check it etc, it would be cheaper just to get a part P registered spark in.

 

[Taylortwocities]

JoyD is right.

If you do it yourself you will have to notify the works and also have to comply with the new wiring regulations BS7671(2008) - this means that you may have to provide RCD protection for all of the circuits in the bathroom (including lighting).