Which cable to run from Leisure Battery to fuse box in rear cupboard?
- Thread starter MikeMc88
- Start date
I think I ran 10mm that should handle about 70amp. A pretty ‘average’ install I’d say.
This might help you Cable Stuff .
This might help you Cable Stuff .
Same here, 10mm fused.
Ideally you need to know what your planning to run from the fuse box and then figure out the draw and add it all up, then bank on 20-25% extra capacity.
Thats my route .
Ideally you need to know what your planning to run from the fuse box and then figure out the draw and add it all up, then bank on 20-25% extra capacity.
Thats my route .
Total up your maximum expected power draw, add a bit for safety and then go up to the next size cable!
FYI 6mm cable is rated to 48 amps so will typically have a usefull maximum (fused) rating of 30 amps.
Edit.
Don't forget about voltage drop. Well remembered by those below
FYI 6mm cable is rated to 48 amps so will typically have a usefull maximum (fused) rating of 30 amps.
Edit.
Don't forget about voltage drop. Well remembered by those below
Last edited:
Thats a fair amount. Your fridge will probably drink quite a bit.
What I did was run a dedicated 6mm cable with in-line fuse just for the fridge, and a separate 6mm cable to the fuse box.
I did this because of reports that the start-up current of the fridge was quite high, and if there is too much voltage drop on the cable then it will not start up.
I reckon 6mm is plenty for what you are doing, particularly if you do what I described above.
Pete
When I figured out my (fairly normal) current requirements, I found I had to massively oversize the cables to keep volt drop down. So at least in my van, 'draw' (or current/Amps) is not the deciding consideration at all.
For instance, Fridge, Heater, lights, water pump combined will use around 12A. 1.0mm cable can handle this, but volt drop over 6m will be 2.8V, obviously unacceptable. 2.5mm cable can carry twice the 'draw', but still volt drop is a nasty 1.2V. To keep volt drop under 0.5V it turns out 10mm is needed (so I used 16mm!)
1. Size the cable for the volt drop
2. Size the fuse for the load
3. Check the cable is big enough for the fuse (it most likely will be)
I hope I don't sound like I'm picking at your method, just trying to help!
Not at all, my reply was a little too generic.
My point was that you need to know why your hooking up to the fuse box to really determine your cable size.
Out of interest what size fuse did you use for the 16mm cable?
I fused it at 30A. If I remember correctly, I couldn't get a smaller MIDI fuse, or I would have used a 20A.
I kept volt drops to a minimum by fitting two 6 way fuseboxes. The first one is only 2m (of cable) from the battery, this feeds the fridge and heater (the main power users, with high inrush). The second fusebox near the rear has only light loads on it.
I have a 6mm cable and a 10mm cable both fused at 30 amps. Would it be best to use the 10mm fused for the higher load stuff like the fridge etc and use the 6mm cable for lower powered stuff such as the lights, tv etc.
I have 3 fuse boxes I can use. A 12 way fuse box and Two 6 way fuse boxes.
My plan was to use the 10mm fused cable with 6 way fuse box to power to fridge which would be around half a metre of wiring to location.
And use the 6mm fused cable with 6 way fuse box to power lights, tv etc which would be around 1.2 - 1.5 metres to rear cupboards.
Would that be a good way to set it up?
I have 3 fuse boxes I can use. A 12 way fuse box and Two 6 way fuse boxes.
My plan was to use the 10mm fused cable with 6 way fuse box to power to fridge which would be around half a metre of wiring to location.
And use the 6mm fused cable with 6 way fuse box to power lights, tv etc which would be around 1.2 - 1.5 metres to rear cupboards.
Would that be a good way to set it up?
Then that makes perfect sense. Be good for that.
My heater takes a fair bit of load to get it started then settles down to minimal once going.
Hi all
Can I just check if you also need a bigger cable for the negative on a fridge. I am wiring my dometic cr50 straight to leisure battery as it’s currently to a pms3 and have some 6mm wire for the positive. There is the existing 4mm negative/ground wire which I am thinking of using or should I replace it with 6mm.
Thanks in advance.
Can I just check if you also need a bigger cable for the negative on a fridge. I am wiring my dometic cr50 straight to leisure battery as it’s currently to a pms3 and have some 6mm wire for the positive. There is the existing 4mm negative/ground wire which I am thinking of using or should I replace it with 6mm.
Thanks in advance.
When you're working out voltage drop, then you need to add the length of both positive and negative cables - If you think you need to uprate the positive cable to 6mm, then you almost certainly need to uprate the negative as well. - But if the negative is routed to the leisure battery via the chassis and good connections, then hopefully the voltage drop through the chassis section is low, its just fridge to chassis cable and chassis to Leisure battery cable you need to consider.
Thanks so much for the reply and that makes perfect sense and I have just ordered some more 6mm wire. Can I just double check the bit about ‘routed to the leisure battery via the chassis’ means that I simply can just connect the negative from the fridge to the negative on the battery and that’s all I need to do so it’s a simple circuit. Getting confused as some information says ground it to chassis.
Thanks Darren
Thanks Darren
