7 pin RV plug
- Thread starter mep1811
- Start date
R_Lefebvre
Expedition Leader
It *might* ground through the trailer coupling, but it would be best to run a ground wire.
R_Lefebvre
Expedition Leader
What exactly do you mean "not the same ground as the lights?"
If you're using quality 7 conductor trailer wire, the ground wire in the cable should be the same gauge as the power wire. IIRC, 10ga on both of those, and 14 on all the signal light wires. 10ga is fine for the grounding, and there's no good electrical reason not to use the same ground wire for the battery and lights.
If you're using quality 7 conductor trailer wire, the ground wire in the cable should be the same gauge as the power wire. IIRC, 10ga on both of those, and 14 on all the signal light wires. 10ga is fine for the grounding, and there's no good electrical reason not to use the same ground wire for the battery and lights.
REasley
Adventurer
7 wire trailer cable comes in a variety of put-ups. The sizes are in the product description ie: 14/7 is seven 14 gauge wires, 14/6, 12/1 is six 14 gauge wires and one 12 gauge wire. There is also 14/6, 10/1 or 14/4, 12/2 and so on. The standard runs; if there is one larger wire it's white (ground). If there are two larger wires they are white and black (aux). Some companies will do custom put-ups for large users, but you'll generally find the most common to be 14/7 or 14/6, 12/1. The ground is usually largest because it carries the negative for all of the rest of the positives.
As far as grounding on the auto side, just use a chassis ground. It is not neccessary to run a ground from the battery. If you find otherwise, you need to address your chassis ground at the battery.
As far as grounding on the auto side, just use a chassis ground. It is not neccessary to run a ground from the battery. If you find otherwise, you need to address your chassis ground at the battery.
sgv209
Observer
I meant that he should use the 10ga wire as you suggested instead of a ground wire the same gauge as the lights, so if he is using an off the shelf 4 wire harness, he should make a new ground instead of using the one from that harness.
This is what I bought. It has 10GA for both the ground and 12V+. The brake wire is 12GA and the rest are 14GA. I hope the 10GA is enough to power my Hellroaring isolator. I plan on running 4-8GA from the battery to the rig's 7-way to cut down the voltage loss on that run but it would be nice to leave the pig tail alone with the 10GA rather than customize it with an 8GA to the isolator in the trailer.
http://www.etrailer.com/Wiring/Hopkins/H20046.html
http://www.etrailer.com/Wiring/Hopkins/H20046.html
R_Lefebvre
Expedition Leader
Ok, that makes sense.
ntsqd
Heretic Car Camper
If you were only running that ground wire it might be a bit small to carry both lighting and charging currents if you're at maximum charge rate for the trailer battery while running the lights. However, don't discount the coupler's ground connection. Unless you are using something like the Treg or Max couplers there is a metal to metal conduction path through the coupler. It is not a great ground, but it will carry some current. I think that this will work fine. Note that greasing the hitch ball will be detrimental to grounding. I'd use graphite if you don't want to run a dry hitch ball.
This is my dilimma now. I would like to install an isolator but use the trailer wiring 10awg that I have from the truck engine bay to the trailer plug. Mike at hellroaring said it should be o.k. with what I have. Something to do with the resistance would actually help the system. Are you putting the isolator in the engine bay or trailer?