Romex Run Under Coach Of 86 Dolphin

[Guest samsterid]

I am trying to safely run Romex under the coach in my 1986 Dolphin - from an Inverter installed close to the batteries over to the RV sub-panel.

From the sub-panel side, I can easily remove the generator flex conduit (don't need that) and re-use that hole.

On the battery side, I was thinking of drilling a new hole close to the two wires that go under the coach to Chassis ground.

I just don't know what I'm drilling through - is there any sheet metal where the two ground wires go down?

Also should the Romex be enclosed in conduit under the cab? i could use 3/4 PVC flex conduit for that - doesn't cost much.

Thanks - Sam

[zero]

"Romex" is just a brand name for an indoor-version only of NM-B cable (originally made in Rome, New York and thus the name). You want waterproof UF-B cable, not NM-B Romex. Adding any sort of flexible conduit certainly won't hurt anything and will give some extra protection from road-gravel. That being said, I've wired many an equipment trailer with plastic-sheathed UF-B and can't say I ever had any get damaged from road-debris. I've got a bunch of 12 gauge UF-B under my RV and it's all in flexible plastic conduit.

[Guest samsterid]

Thanks JD - will look around for the waterproof stuff.

Any idea what's under the carpet here that I need to drill through?

From underneath there is a very thin layer of sheet metal - hoping the rest is just plywood with maybe some insulation . . .

Sam

[Guest samsterid]

Now I have noticed another type of wire sold by the foot at Orchard Supply.

SOOW or SJOOW wire - seems easier to work with than NM-B or UF-B and maybe wouldn't need any conduit?

Sam

[snail powered]

I am trying to safely run Romex under the coach in my 1986 Dolphin - from an Inverter installed close to the batteries over to the RV sub-panel.

From the sub-panel side, I can easily remove the generator flex conduit (don't need that) and re-use that hole.

On the battery side, I was thinking of drilling a new hole close to the two wires that go under the coach to Chassis ground.

I just don't know what I'm drilling through - is there any sheet metal where the two ground wires go down?

Also should the Romex be enclosed in conduit under the cab? i could use 3/4 PVC flex conduit for that - doesn't cost much.

Thanks - Sam

You might want to use Romex (triplex flat wire) that is made for situations where there will be flex. It is made with multiple small strands of twisted wire instead of one larger solid wire. It is an industry standard to use the twisted wires for automotive situations rather than solid wire. Flexing can cause work hardening in thicker solid, single strand wire causing it to fracture the wire/ I purchased it by the foot at my local marine supply store. The best versions of this product are fully tinned. But for interior work I used the standard version without tinning for the cost savings.

http://www.fisheriessupply.com/ancor-standard-tinned-triplex-boat-cable-flat

Of course you can also use a triplex round wire instead of flat. Your choice, the convenience is in having all the wires inside of one outside jacket. The shape of the wire is a personal choice for what you want to use for clamping it in place on the wire runs. Of course you don't need as large of a hole diameter for round wire to pass through if you are going to be running it through solid structures such as the floor.

http://www.fisheriessupply.com/ancor-standard-tinned-triplex-boat-cable-round

[zero]

You might want to use Romex (triplex flat wire)

I don't mean to be redundant or picky, but "Romex" is an indoor, NM-B, dry location wire only.

[Maineah]

You can use THHN inside of plastic conduit. I have no ideal where the Greenfield is going if it's out side it will rust like crazy and is not water tight. If you want flexible stuff they do make liquid tight flexible conduit. and fittings. For 3 #12 wires 1/2" is plenty big enough.

[Guest samsterid]

Ah - Greenfield is metal flex conduit - was not planning on using that. I have 5 wires to run: #12 for AC IN, and #14 for AC OUT, plus ground - would 1/2 inch Liquidtight still be ok?

@snail - thanks for the tips on the marine grade wire - I even found it by the foot here:

But now I'm leaning towards the SOOW cable - the "W" means it's suitable for wet areas and it's very easy to get locally.

I'm thinking I would run the last 2-3 feet (near the wheels) through some Liquidtight flex cable to protect it from gravel and excessive water.

There are some wires in use right next to where I have to go up with this feed that seem like they have been there for 30 years with no problem.

I don't think they are marine grade!

BTW - both of those two old white wires terminate in a lug attached to the chassis, and they both go back to the same negative post on the battery. - do I really need two of them?

Sam

Edited August 26, 2015 by samsterid

[Maineah]

THHN is pretty tough stuff it is stranded and pretty water proof and a lot easier to pull you should be able to get your 5 wires in a 1/2" pipe. Suck a pull string in with a vacuum cleaner it will make it easier to get your wire in.

[Maineah]

Ah - Greenfield is metal flex conduit - was not planning on using that. I have 5 wires to run: #12 for AC IN, and #14 for AC OUT, plus ground - would 1/2 inch Liquidtight still be ok?

@snail - thanks for the tips on the marine grade wire - I even found it by the foot here:

But now I'm leaning towards the SOOW cable - the "W" means it's suitable for wet areas and it's very easy to get locally.

I'm thinking I would run the last 2-3 feet (near the wheels) through some Liquidtight flex cable to protect it from gravel and excessive water.

There are some wires in use right next to where I have to go up with this feed that seem like they have been there for 30 years with no problem.

I don't think they are marine grade!

BTW - both of those two old white wires terminate in a lug attached to the chassis, and they both go back to the same negative post on the battery. - do I really need two of them?

Sam

Yes you do need the white wires. Your 120 volt grounds should be grounded to the frame also. You going to use a GFI ?

[Kane]

West Zmarine sells really nice Marine grade wire looks like Romex but is obviously for outdoor exposed.

[Guest samsterid]

After reading that NM-B or Romex should not be enclosed in conduit due to possible overheating, this is what I've got going.

I used a short length (12 inches) of Liquidtight flex conduit to run some SJOOW cable through the floor at each end.

SOOW seems to have similar features to marine grade cable. (J is for Junior - good for up to 300 volts)

Overall, SOOW cable resists oil, solvents, water, ozone, aging, and abrasion. It is also flame retardant, flexible, and durable.]

So I ended up with about a 4 foot run of SJOOW cable under the coach that is not in conduit - It is away from the muffler and not near the wheels, but I will keep an eye on it.

Thanks - Sam

Edited September 1, 2015 by samsterid

[zero]

After reading that NM-B or Romex should not be enclosed in conduit due to possible overheating, t

Thanks - Sam

Who the heck wrote that? It is not only allowed, it is called for in certain installs.

National Electrical Code 2011 ARTICLE 334 Nonmetallic-Sheathed Cable: Types NM, NMC, and NMS II. Installation

334.15 Exposed Work. In exposed work, except as provided in 300.11(A), cable shall be installed as specified in 334.15(A) through ©.

( Protection from Physical Damage. Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, Type RTRC marked with the suffix -XW, or other approved means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, Type RTRC marked with the suffix -XW, or other approved means extending at least 150 mm (6 in.) above the floor. [ROP 7-94] Type NMC cable installed in shallow chases or grooves in masonry, concrete, or adobe shall be protected in accordance with the requirements in 300.4(F) and covered with plaster, adobe, or similar finish.

[Vanman]

If the wire even comes close to overheating it's way too much the wrong size and overfused.