How difficult is it to run wiring in foam walls in trailer?

[profdant139]

My small inverter is starved for juice -- I am pretty sure it is because we have it running off the thin 12v wire that feeds the cigarette lighter socket. I want to run heavier wire from the converter to the inverter.

My question is pretty simple -- how to fish the wire? The wall panels are a sandwich of paneling and styrofoam. It is not like fishing wire at home, where there are voids between the studs. Will ordinary "fish tape" penetrate the dense foam?

Thanks in advance for your advice. Obviously, I am not yet an expert at electrical repairs.

[profdant139]

time2roll, you are right that extension cords running around the interior are not pretty. But these would be for occasional use -- not permanently installed. When not in use, the cord is rolled up and stowed neatly.

[time2roll]

profdant139 wrote:
This solution, if it works, avoids the issue of hooking the inverter to my converter.

The converter is just one component in the distribution panel.

You could connect the inverter power to the single circuit you need and not power up the entire panel. Yes if the converter happens to draw power off that same single circuit you could easily make adjustments so the converter component never gets powered up by the inverter.

If you prefer extension cords or surface wire molds from the inverter mounted in the front compartment that will work. Not my style.

[profdant139]

2oldman, that link discusses a much more elaborate inverter setup than I want or need. But there was one very useful paragraph:

"After removing the original converter and it's wiring, I installed heavy duty battery cable to connect the inverter directly to the batteries. It's important to use heavy enough wire here, as some larger inverters can draw several hundred amps when under full load! My inverter required 6 ga. wire. I also twisted the heavy wire to help eliminate any electrical interference when operating the unit in charge mode. A fuse was used to protect the system from meltdown. I used a 100A fuse connected directly to the positive terminal of the battery."

This tells me that I can hook my much smaller inverter to the battery directly. I won't need 6 gauge cable -- I think the very light loads that I will draw will be fine with ten gauge.

Just to be clear, the inverter will be completely separate from the rest of the electrical system within the trailer.

[Naio]

2oldman, I don't see the inverter in that.

And profdant, don't worry, the newbie questions are helpful to me and, I bet, many others!

I will add that surface conduit, which is made for sticks and bricks wiring, is kind of giant for 12v wiring (and surprisingly expensive). You might consider getting some thick-housinged wire and just running it behind/through cabinets and stuff, if you can find routes where it will be protected. I am guessing that your rig is like mine and does not have a lot of bare wall space ;).

[MEXICOWANDERER]

The non-ability to simply run a wire through foam sandwich has been adequately IMHO. I had a job in the late 80's in which it could not be avoided and the unit was a near new Alpenlite thirty footer.

The load was 30 amperes and the owner insisted on not running wire under the unit. Flexible waterproof conduit never has been cheap and it wasn't even back then. So the owner stripped panels and cabinets off the walls (side opposite the refrigerator). Because of the length and because of the insulation factor I decided to use 6AWG wire. A router was used making parallel grooves and where the wall met bulkheads, a sharp wood chisel was employed. Splotches of canned foam were applied to adhere the cable into the foam. It took him over a week to do the panel removal and replacement. As an aside he discovered really stupid manufacturing defects like multiple staples punched into the 120 vac wire in the bathroom. My decision was and is this is a big - big job. His forté was to run an inverter and HAM radio in the bedroom via a Trace 812 inverter. He ganged eight Trojan T-105's in the front cargo area under the 5th wheel overhang.
I wired Quicksilver with four once inch PVC tubes per side, with wiring breakouts to avoid this problem. Good luck with your project. A near to the batteries inverter is the way to go.

[2oldman]

12v side of life.

This is the usual recommended reading for wiring.

[profdant139]

One more answer to Niner's questions -- my old inverter was 400 watts, but it died of old age and overuse. I bought an 800 watt unit, thinking bigger is better, but it gives a low voltage reading when I am running my pump and my furnace at the same time. (When I read voltage at the battery, I have 12.7, but the inverter sometimes shows 12.0 or less.) . That is why I think this is a wiring problem -- it is like drinking a thick malt through a thin straw.

I use the inverter for minor things, like recharging my laptop and phone. So we still do need a little 120v power, even when boondocking. And yes, it has an on/off switch, to kill the parasitic draw when not in use.

[2oldman]

profdant139 wrote:
2oldman, when you say "nobody hooks it up this way," do you mean no one hooks the inverter to the converter? Or do you mean no one hooks the inverter right to the battery?

Nobody hooks an inverter to a converter.. not directly anyway. Everybody hooks an inverter directly to the battery..if you want to run anything that takes more than a few amps.

Hooking the inverter to the converter would imply you have 120v power to the converter.. which means you don't need to use an inverter. I'm not sure what you mean by this.

[profdant139]

2oldman, when you say "nobody hooks it up this way," do you mean no one hooks the inverter to the converter? Or do you mean no one hooks the inverter right to the battery?

And Niner, when you say "wire it to the 12v side of the panel," are you saying wire the inverter to the converter panel?

Again, guys, I apologize if these are simplistic questions, but I have zero experience in this particular area. Please try to be patient with us newbies -- thanks. Not everyone is an expert in everything.

[NinerBikes]

Get a good amperage rated on off switch, wire it to the 12v side of the panel first, then wire in the inverter after the on off switch with it's 120v outlet.

How many watts is your inverter? You need to be able to turn the inverter off to reduce parasitic load, when not in use.

What is in your TT that you need 120V?

[2oldman]

profdant139 wrote:
This solution, if it works, avoids the issue of hooking the inverter to my converter.

What do you mean by this? Nobody hooks it up this way.

And you simply plug your coach 30a cord into the inverter. Turn off the HW and converter. No fishy wiring involved because it's already there.

[profdant139]

It never occurred to me to mount the inverter near the battery, but I think I could do that.

Please forgive the simplistic questions, but does that mean that I could attach leads to the battery and then come right through the front wall of the trailer to the inverter? I would seal the holes in the trailer -- the batteries are on the tongue, inside plastic battery boxes.

I would then mount the inverter on the inside of the front wall and run a 120v cord from that point, using surface wire mold.

This solution, if it works, avoids the issue of hooking the inverter to my converter.

This sounds too easy -- I think I am missing something.

[time2roll]

If there is an existing outlet you do not need to pull wire.

Move the inverter close to the power distribution panel.
Use the main battery feed to get 12 volt power.
Use a small transfer switch to send power down the existing wire to the outlet.
I assume the inverter is 500 watts or less. With a larger inverter it is best to mount near the battery.

[Matt_Colie]

Dan,

You idea is wrong from the start.

You need the inverter as close to the house bank as you can possibly get it, but still have it be in a protected place and not exposed to the battery acid vapor. It does not matter where it ends up because the 12V current is 10 times the 120V current. The 120V you can run in a household extension cord to the other end of the trailer with very little loss.

You won't ever fish wires (particularly the size you need) though the laminated walls of a modern trailer. But you can get surface wire mold at any big box and put the 120V cord in that. When I quote internal wiring and surface wiring in an RV, they always pick the surface way. Funny thing.

We did a lot of boat work before the depression and I ran into this a lot. The problem was always the same and the fix was always the same.

Matt

[ScottG]

I dont think you can fish it in the usual way. The foam is hard enough that if you just try to push a point through it, the material just balls up and the channel gets bigger and bigger until the ball of material stops you.
Can you go under the floor?