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Old 02-25-2018, 02:08 PM   #1
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Extension Cords?

So I see alot of people saying they are using extension cords for the interior wiring on their bus.

Why? And what kind of extension cord do you use?
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Old 02-25-2018, 02:29 PM   #2
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I have seen a number of folks using SO or SOJ wire for their bus 120v wiring.

The argument for using it is that stranded wire is considered better suited for mobile application than solid wire.

The argument against is that it is NOT code accepted for this application.

I have also seen a product that is essentially stranded Romex intended for marine 120v wiring.

I saw this used in the Marathon Coach factory several years ago. The electrician there claimed that it met NEC and RVIA code. I have not verified that.
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Old 02-25-2018, 03:28 PM   #3
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As far as I am aware, there are no codes for RV wiring. The RVAA is a voluntary industry organization that is still putting their seal of approval on flimsy motorhomes.

There are, however, best practises. Most people still use Romex for their 110V wiring. Will it break? Who knows, but Thomas used it to wire the four passenger heaters in my bus and they were all still working 18 years later.

Use whatever you feel comfortable with because I don't think you'll have an issue with either if you install it sensibly.
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Old 02-25-2018, 03:49 PM   #4
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But Romex what? I have seen 12/3, 14/2 and a half a dozen others.

I need to run a very basic AC system to get some outlets working in the bus as I renovate it. Right now the previous owner spliced an extension cord to romex he ran inside the RV to just plug in to his house but I am not exactly trusting his wiring.

I want an 50A shore connector and a 15A connector to a fuse box and then run 1-2 outlets off that to start. Still trying to work out the details so I dont have to re-do everything once I get the full system in.
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Old 02-25-2018, 04:28 PM   #5
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i was reading a post earlier where the guy put up a video saying he did his mostly in 12/2, with a little 14/3 for certain lights. ill try and find it
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Old 02-25-2018, 08:06 PM   #6
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The whole subject of using extension cords for 120VAC wiring inside the bus has been discussed, sometimes very acrimoniously, many times on this and other forums. Fred Hobe does it, many others have also used it, but some folk get the heebie-jeebies when you mention extension cord and RV in the same sentence. Yes, extension cords are UL-rated, but their UL rating is for use as a temporary extension cord not inside conduit, not for permanent wiring in a vehicle. Gut feeling tells me that appropriately-sized extension cords will work just fine as long as they're not inside conduit or close confines. Mind you, solid-strand wiring such as Romex will also work just fine in a bus if it's properly supported to prevent any movement at all, and I mean any movement. Long unsupported lengths of Romex dangling in mid-air and bouncing around every time you drive over a bump (yes, Winnebago, I'm looking at you) is a recipe for problems, but if used intelligently it should be OK. I used some AFC MC-Lite metal-sheathed solid-core 10/2 for my 30 amp wiring from the generator and the two shore inlets, but it's secured every 10 to 12 inches and does not move at all. Obviously you cannot crimp terminals onto solid wire, but I found that forming the ends into small loops for the terminal screws works just as well as crimped-on lugs for stranded wire.

The NEC does not apply to RVs, let alone to self-built bus conversions, and the RVIA are a bunch of self-serving RV makers who are trying to convince gullible RV buyers and RV park owners that an RVIA sticker means anything. NFPA 1192 is more pertinent for us home-converters, but even then some of its provisions are of questionable relevance to us. I'm cognizant of the NEC and 1192, but I'm not slavishly following their specifications, merely using them as the starting point and making my own final determinations. Boating and marine standards may be more pertinant to us, but some of their stuff is very spendy (have you priced Ancor tinned marine wiring recently? Ouch.)

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Old 02-25-2018, 08:37 PM   #7
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Originally Posted by PNWorBUST72 View Post
But Romex what? I have seen 12/3, 14/2 and a half a dozen others.

I need to run a very basic AC system to get some outlets working in the bus as I renovate it. Right now the previous owner spliced an extension cord to romex he ran inside the RV to just plug in to his house but I am not exactly trusting his wiring.

I want an 50A shore connector and a 15A connector to a fuse box and then run 1-2 outlets off that to start. Still trying to work out the details so I dont have to re-do everything once I get the full system in.
The wire gage you use depends on the draw of the devices on that circuit. 14ga is fine for most circuits but if you're powering hi draw stuff like electric cook tops and coffee makers you'd want 12ga. 14ga gives you 15 amps of power and uses a 15 amp breaker at the panel. 12ga wire gives you 20amps of power and get a 20amp breaker. Your 50amp shore power connection needs a 50 amp breaker at the panel.

12/3 is 12ga with two hot wires in the sheath. Generally you'll use 12/2 or 14/2 for your circuits. As others have said, solid wire will work fine with proper support but stranded wire is preferred. I used 12ga metallic cable for my two 120v circuits and 10ga metallic from the power panel to our 30 amp RV shore power plug.

The 50 amp connections aren't available at all RV parks but if you'll be running multiple roof AC units you'll need the power.

Ground your panel to the body.
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Old 02-25-2018, 08:50 PM   #8
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I was planning on running 12/2 in conduit for my 110 in the bus. Iceni, are you saying I should not put it in conduit? My thoughts were it would provide protection for the wire. Will it cause excess heat build up or something?

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Old 02-25-2018, 09:00 PM   #9
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Originally Posted by Genghis View Post
I was planning on running 12/2 in conduit for my 110 in the bus. Iceni, are you saying I should not put it in conduit? My thoughts were it would provide protection for the wire. Will it cause excess heat build up or something?

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z
You would need to look up the NEC deratings for putting it inside conduit. Heat buildup is the reason for the lower ampacities when inside conduit.

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Old 02-25-2018, 09:01 PM   #10
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My thoughts were it would provide protection for the wire. Will it cause excess heat build up or something?

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z
Protection from what?

Your wires will be run through, or otherwise attached to framing along their whole length and safely secured behind some form of sheathing.

Sounds decently protected to me
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