Cable rating

An alchemy of sparks, copper wire and earth

Moderators: Moderators, User administrators

Post Reply
Teeaitch
Posts: 11
Joined: 14 Jun 2017, 12:07
80-90 Mem No: 0

Cable rating

Post by Teeaitch »

I'm planning on fitting a 140amp VSR split charger. As usual, I'm confused about what rating cable and fuse I should use. Can anybody put me in the picture please, and while we're at it maybe someone can put me in the picture about how to calculate for this kind of issue. Thanks.

Funkychops
Posts: 17
Joined: 01 Jul 2020, 15:39
80-90 Mem No: 0

Re: Cable rating

Post by Funkychops »

Fuse should be rated lower than the cable (so that the fuse goes first)

I think a general rule of thumb is 1.25x normal current for the fuse rating (http://www.judgeelectrical.co.uk/domest ... ating.html). Using P=IV you should be able to work out the current draw for the appliance.

Then make sure the cable rating is higher than the fuse. Your safety margin depends on various factors like environment, number of cables in the run etc but all this is doing is making sure the wire doesn't get too hot to cause a fire. You can't really go too high - all higher does is give you a thicker and less manageable cable.

For VSR connections to battery and earth, you need to go big in terms of cable rating. Should be able to find out the exact charge current going into the battery but I would imagine it's high
1983 2L Air Cooled (CU) T25 Hightop
Based in Bristol

Teeaitch
Posts: 11
Joined: 14 Jun 2017, 12:07
80-90 Mem No: 0

Re: Cable rating

Post by Teeaitch »

Thanks for that.

User avatar
Mocki
Membership Admin
Posts: 15162
Joined: 29 Sep 2005, 09:27
80-90 Mem No: 428
Location: Mansfield tel/txt 07947137911
Contact:

Re: Cable rating

Post by Mocki »

There is no point using cable that’s rated more than the out put of the alternator, it’s never going to exceed what the alternator can produce . 
16mm2    
 
Steve
tel / txt 07947137911
Image
just one shade of very fast grey
________________

1989 2.1LpgWBX HiTop Leisuredrive Camper

Post Reply