crossing under floor with major wires

[Virgil Jones]

[font=Verdana, Arial, sans-serif]I'm very tall so my bed will be along the drivers side wall.  I will be putting AGM batteries under the bed.  On the passenger side wall I will have the kitchen...sink w/pump...propane stove...Dometic frig... lights...plug-in outlets for a/c and d/c.   [/font]

[font=Verdana, Arial, sans-serif] I plan on running a pair of SHEATHED 4 gauge cables in a groove under the 5/8inch plywood (in the area where the framework and insulation will be). One cable for d/c from the battery and one cable for a/c from the inverter.  They will be going to fuse panels under the kitchen counter and then spread smaller wires where necessary.  Has anyone done this? [/font]

[font=Verdana, Arial, sans-serif] This seems easier than running the wires around or through the ceiling. I also plan on having a second fuse panel on the battery side to take care of that side of the van.  I'm not sure whether to run one cable off the batteries and then split it at a junction box to the two sides or run two seperate cables off the batteries.  Virgil[/font]

 

[djkeev]

As long as the wires are in a conduit or in a framed channel you are fine.

If they will in any way be pinched or stepped upon under wood or carpet, do NOT do this!

Dave

 

[blars]

You won't need 4-guage for the AC, but you will need 2+ground for it. 12 gauge should be big enough unless you have more than a 2kw inverter.

 

[ccbreder]

I wish I had thought of transverse when I did my floor. I did run conduit from the back to front. I ended with 12 volt wires mid way across the top, and the 120 volt went around the back above the doors before 1/2 way front.. 10 AWG 2 conductor for 12 volt. and 12 AWG 2 + green for 120 volt. All marine wire. You dont need conduit if you dont have sharp edges to cut the insulation. marine has best insulation.

 

[djkeev]

I wish I had thought of transverse when I did my floor. I did run conduit from the back to front.  I ended with 12 volt wires mid way across the top, and the 120 volt went around the back above the doors before 1/2 way front.. 10 AWG 2 conductor for 12 volt. and 12 AWG 2 + green for 120 volt. All marine wire. You dont need conduit if you dont have sharp edges to cut the insulation. marine has best insulation.

Yes, for a wire run with no pinching possibilities or not under carpet or plywood where wires will have the possibility of being compressed by furniture, foot traffic or cargo, you don't need a conduit. 
IF the possibility exists, I don't care the wire quality, do NOT run it unprotected! 

What will happen? ..... Probably nothing.
What could happen? ...... At best a short circuit and you blow a fuse...... At worst a horrific Van engulfing fire. 

Dave

 

[Virgil Jones]

sounds like conduit it is!  Possibly 2 runs of conduit...one for a/c and one for d/c.  I hate fighting to get wires thru conduit.  I will probably put polyiso around the conduit as much as possible to it is not just on the man metal for condensation purposes.

 

[BradKW]

sounds like conduit it is!  Possibly 2 runs of conduit...one for a/c and one for d/c.  I hate fighting to get wires thru conduit.  I will probably put polyiso around the conduit as much as possible to it is not just on the man metal for condensation purposes.

Biggest mistake people make is trying to feed wire through conduit that already has wire in it....gotta take all wires out, make a nice, pointed taped-up bundle, and pull through all at once with your tape or fishing line. There's even wire lube, but can't see you needing that...just make sure you get all the wires in one shot, maybe add a couple extras.

With something small like a van, you could probably just assemble the conduit with wires in it...if you have 90's, might be the way to go, otherwise you'l need to anchor conduit down strongly enough to withstand pulling through...

 

[vanman2300]

I agree the gauge seems pretty much overkill. The other concern is that if you are running serious power through it you'd better make certain that the wire doesn't heat up. Once you enclose a wire that does create heat then you've also created a fire hazard.

 

[djkeev]

I agree the gauge seems pretty much overkill. The other concern is that if you are running serious power through it you'd better make certain that the wire doesn't heat up. Once you enclose a wire that does create heat then you've also created a fire hazard.

While this is I'm sure a possibility....... It isn't something to lose sleep worrying about. 

Under sized wire will create heat as you draw power through them. Simply too much resistence as it passes through. 
It is far better to oversize a wire if in doubt. The larger wire will pass all the electric you need without fear of over heating. 

Dave

 

[Virgil Jones]

I agree the gauge seems pretty much overkill. The other concern is that if you are running serious power through it you'd better make certain that the wire doesn't heat up. Once you enclose a wire that does create heat then you've also created a fire hazard.

I might be under the bigger the wire the better syndrome.  I understood that the bigger the wire the less chance of it heating up.

 

[vanman2300]

That's good then. I was in the wire and cable business for years and usually heavy gauge meant big time voltage. The gauge still seems incredibly large though. Even 8 gauge would be plenty.

 

[djkeev]

I agree, size appropriately but don't get carried away.
We are talking very short runs with what will most likely be low draws. An electric space heater might be the biggest draw? If so, A 12 gauge wire is more than sufficient.

BTW, the higher the voltage, the smaller the wire you can safely use to transmit it a given distance.

Dave

 

[ccbreder]

Using this chart; http://www.genuinedealz.com/custom-cables/custom-battery-cable-assembly
Your 4 AWG will safely carry more than 100 amps at 12 volts. I would fuse for that at the battery. Put a fuse panel at the other end to fuse for the other branch circuits. The voltage drop would be how you select the size wire you use. Higher amps, larger wire.