Wire gauge for frame ground?

[JRRNeiklot]

What size wire should be used for frame ground on a small travel trailer?  Stock was 8 gauge, but I'll be running an air conditioner that pulls about 450 watts.  Should I upgrade the wire size?

Thanks.

 

[B and C]

Are you plugged into shore power and using it to power the AC? If so, 8 Gauge is overkill for a 120V circuit. If you are trying to run it off batteries, your 12V DC cables will need to be a lot larger; probably down in the 1/0 gauge area to your inverter.

 

[JRRNeiklot]

I have 3 100 amp hour lithium batteries. I'm using 2/0 cable for the batteries and inverter cables. Renogy suggests a 10 awg cable for the inverter ground. I'm asking about the frame ground from the trailer's main power. Sorry if I was unclear.

 

[B and C]

I don't know about grounding an inverter in a mobile application. If the inverter is supposed to be grounded in a mobile application, your 8 gauge existing ground is bigger than the 10 gauge the inverter calls for. My ground through my 30 amp shore power connector is only 10 gauge.

 

[Weight]

What do you mean by "ground". If the cable is to connect the battery negative to the frame, no less than 2/0. If the "case ground lug" on the devices, use what ever the manufacturer recommends or larger. If you mean the alternating current 120 volt, the frame needs be connected to the green wire back to the service panel near the meter. Do not connect the white or black (neutral or hot) wire to the chassis, only the green.

 

[JRRNeiklot]

My batteries are inside, so I'm redoing the whole system. There are two 8 gauge wires from the trailer that original went to the batteries on the tongue.. The negative side also has a wire coming off it that is attached to the frame. Since I have more than tripled my battery capacity and loads, I'm wondering if I should upgrade that wire.

I am not an electrician, so apologies for any vague descriptions.

 

[Weight]

I posted here yesterday. Guess it didn't take. The 8awg wires should all be upgraded. Blue Sea has a easy selector chart to use for your circuits. http://circuitwizard.bluesea.com/

You need the maximum ampere expected on each wire. You need the length of each wire. Some charts you input the round trip, others just the one way. I use bus bars to connect multiple circuits to one point, such as battery. https://www.bluesea.com/products/2104/PowerBar_600A_BusBar_-_Four_3_8in-16_Studs

Then i have fuse at battery positive and smaller fuse at bus bar. https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A

It is good practice to connect the negative battery to the chassis as well as having separate negative cable to critical devices.

 

[JRRNeiklot]

One more question, if I may. Since the trailer power already has a frame ground, is it necessary to run a separate ground straight from the battery?

Thanks.

 

[B and C]

What trailer power already has a frame ground, shore power or battery?

 

[JRRNeiklot]

I'm guessing it's dc. I'm a novice at this. The wire comes from the trailer to the frame to the battery.

 

[Weight]

That is the negative ? What do you differentiate between "trailer" and "frame"?

 

[RvDreams]

You just told us that the battery is grounded to the frame (probably 8 ga you talked about earlier) and the cable keeps going into the trailer to parts unknown. If you have any heavy use items like your inverter negative cable connected to the frame, the existing battery to ground cable needs to be 1 size larger than your inverter cable to account for other loads.

 

[JRRNeiklot]

Since that wire goes to "parts unknown" how am I supposed to replace it? Renogy recommends a 10 gauge cable for the inverter ground.

 

[B and C]

You have to chase it out. If it goes under the trailer, follow it there. If it goes through a wall or floor, measure on the outside where it does and then go inside to measure. It usually is not too difficult if you don't have belly pans.

My guess is it goes to your power center inside.

 

[JRRNeiklot]

Yes, it goes to the power center (I assume), but at some point it transitions into a different wire, I haven't had any luck chasing it down. It disappears under the tanks and stuff long before it enters the trailer.

 

[RvDreams]

It might enter the trailer above a tank. Start looking above right where you lose it below. Time to go inside and start opening cabinets, lifting cushions or whatever to get to floor level and look. It may come up in a hidden spot like behind the fridge, water heater, furnace...

 

[B and C]

Time to start looking inside for it. Open base cabinets, look behind the fridge, at the furnace, etc.

 

[Weight]

You can leave that cable to do its own thing and run new cables to the inverter. What about the positive battery cable? Where does that go?

 

[B and C]

I am with Weight on this one. Just run new cables from the battery to your inverter with a fuse at the battery. Everything else can remain the same. Put the inverter close to the battery and then run 120V to your AC.