what size wire and relay? (12volt)

[HERTS P&D]

Hi, I have scene lights on side elevation of my van. There are 2 lights with a total of 140 wattage. The question is what gauge wire do I use and what size relay?

I thought I would try here first before the motoring section.

Andy

 

[EFLImpudence]

Assume it's 12volts:

140watts / 12volts = just under 12amperes

Have a look on link for wire size.

http://www.powerstream.com/Wire_Size.htm

 

[EFLImpudence]

Might be helpful:

Load (lights) 12A
Fuse 12A (maybe next size up)
Wire - capable of taking more current than the rating of fuse.
Relay - capable of taking more current than the rating of the fuse

 

[HERTS P&D]

What wire do I need from the list below?

http://www.maplin.co.uk/search?criteria=Wire

Andy

 

[EFLImpudence]

I expect you will have to get 16A fuse (don't think they do 12-15) so you will need AWG17 wire (or lower number - lower the number = bigger the wire).

Not sure about Maplin sizes. I will look into it.

Go to a Motor spares shop and ask for 20A wire.

 

[EFLImpudence]

Not 100% sure of Maplins sizing but I think it will be the

*Deleted wrong information*

Ask them if it will take 20A - they should be able to tell you.

 

[HERTS P&D]

Many thanks for all of your help.

I have just made my shopping list and will be there tomorrow morning.

Andy

 

[EFLImpudence]

I worked out the Maplin wire wrongly.

You need something between the 32/0.2 and 50/0.25 sizes.

If you get 16A fuse then any cable over 16A - that's the important bit.

I would try car spares first.

 

[aaronjb]

Halfords sell 5, 8, 17 & 27A automotive cable on reels in a variety of colours for <£4 a reel.. 17A would do you nicely with a 16A fuse.

 

[bernardgreen]

From bitter experience I know that automotive cables tend to be rated at the top limit of the current they can carry. A wire that over heated and welded the insulation of other wires together. Fuse rating was lower than the rating of the over heating cable.

Also voltage drop can be significant so use cable rated at double the expected current or more.

 

[HERTS P&D]

UPDATE:

All lights are wired up and working.

Many thanks for all posts.

Andy

Untitled

• HERTS P&D
• 11 Jun 2011
• 1

Untitled

• HERTS P&D
• 11 Jun 2011
• 1

Untitled

• HERTS P&D
• 11 Jun 2011
• 1