Shared earth.

[Howmanygoes]

I am looking to add a few extra lights and circuits to my roof top set up. I am limited on space for running cables up and was planning on using a common earth with branches off once it’s up to the rack.

Would the cable thickness be based on the same method as a positive, ie. amp requirements and distance. As a shared earth does it need the total amps if everything was on

Ie. 50” light bar 25a + 5a working light +5amp usb charger socket. Totals 35a. So 35a “riser” plus branches of 25a,5a,5a (subject to distance)

Alternatively should I earth them to the roof rack mounts if I have continuity and just run the positives up?

 

[steverjuk]

The problem is that the resistance of the earth will affect the brightness/reliability of the lights, personally, I'd run a nice thick earth cable up to the roof rack from the battery and then common them all back to that if you have space/cable if not then you could get away with earthing to the body of the truck/roof rack a 4 or 5 awg cable should be more than enough for this.

 

[Howmanygoes]

The problem is that the resistance of the earth will affect the brightness/reliability of the lights, personally, I'd run a nice thick earth cable up to the roof rack from the battery and then common them all back to that if you have space/cable if not then you could get away with earthing to the body of the truck/roof rack a 4 or 5 awg cable should be more than enough for this.

Thanks Steve. That was my original thought, an earth umbilical from the battery, branching off to each outlet.

 

[Chris]

To keep mine neat I put a grommet in the duct to the airbox and an exit grommet near the top of the snorkel and ran the power to the roof lights up the snork. When I say grommets I do mean watertight, not an O ring before people start wring in.

 

[steverjuk]

I'm sure a hole for the cable filled with tiger seal will work in the snorkel as well, that stuff sticks like dog sh*t.

 

[Towpack]

Seeing as how a snorkel should be water tight you should ideally be looking at an IP rated cable grommet, available in plastic or chromed brass. I used these for the cable entry points on the roof and that’s just to keep the water out from rain and washing, never mind immersion from a deep water crossing. JMO

https://www.ebay.co.uk/itm/PACK-OF-...054743?hash=item1ed48d6397:g:Re8AAOSwnDZUCatr

 

[StarCruiser]

Seeing as how a snorkel should be water tight you should ideally be looking at an IP rated cable grommet, available in plastic or chromed brass. I used these for the cable entry points on the roof and that’s just to keep the water out from rain and washing, never mind immersion from a deep water crossing. JMO

https://www.ebay.co.uk/itm/PACK-OF-...054743?hash=item1ed48d6397:g:Re8AAOSwnDZUCatr

Totally agree. No harm in adding Tiger seal around the hole when fitting each of these though.

 

[steverjuk]

Yea that's what I ment gromit / gland and shit loads of tiger seal, it's not like it's not going to help.

 

[StarCruiser]

I was referring to a cable gland and a light to medium smear of sealant but hey, whatever floats your boat.

 

[moggy1968]

I was referring to a cable gland and a light to medium smear of sealant but hey, whatever floats your boat.

Or your landcruiser