Which 120V wire?

[Airwave503]

Hi, I am wanting to replace all the 120V wiring in my '61 Safari while I have the inside skins out. I don't plan on being hooked up to shore power all that much and I never plan to have an air conditioner. Someday I would like to have a microwave, hybrid refrigerator, maybe a TV.

Given this, is just a regular 3-prong receptacle adequate for the shore power inlet? 15A I think it's called?

I picked up some Cerrowire indoor 12-2 NM-B w ground at Home Depot. Is this the right wire for my needs?

Thanks!

[Melody Ranch]

STOP! Don't buy anything else until you do some homework here about electrical. It will save you some money. You always should plan ahead for what a future sale will demand.....nothing special, just right.

[Airwave503]

Thanks Melody. I have been doing lots of reading on here and elsewhere and have been stuck on the electrical planning phase for too long. Right now I just want to get the right wire in the walls so I can insulate and get the inside skins back in. <sigh>

[DavidsonOverlander]

Originally Posted by Airwave503

Hi, I am wanting to replace all the 120V wiring in my '61 Safari while I have the inside skins out. I don't plan on being hooked up to shore power all that much and I never plan to have an air conditioner. Someday I would like to have a microwave, hybrid refrigerator, maybe a TV.

Given this, is just a regular 3-prong receptacle adequate for the shore power inlet? 15A I think it's called?

I picked up some Cerrowire indoor 12-2 NM-B w ground at Home Depot. Is this the right wire for my needs?

Thanks!

15 Amp circuits are usually supplied by 14 ga wire. 12 ga wire is for 20 amp circuits. 12/2 wire will be more expensive, heavier and more difficult to work with, so I'd return it and get 14/2 if you can. I used 14/2 Aluminum BX Cable (the conductor is copper, the sheathing is aluminum) although you could also use Romex. I used the BX for added protection because even though I had the walls open to re-insulate I ran most of the wiring on the inside of the inside panels through cabinets, under beds, etc. This was partly to keep the wire where it was accessible in case I decided to make changes later and partly for convenience as we've been camping in the trailer while working on it and this allowed for a slower process.

I'm not an electrician, just sharing what I did.

[Melody Ranch]

I think that if you approach the project with a confident attitude you will find it an easy job.

Go ahead and use 12 x 2 wire. Use a Marino style inlet..it is 35 AMP (RV type power) but a small cheap adaptor will plug in when you need it for 15 AMP (home type power) service. Look at these diagrams...very simple. Your best bet will be use a Progressive Dynamics converter and a small 12 fuse panel. Bay or Amazon for cheap sale items.
Start with a new battery too. These items will do what you want and will make you upgrade ready. I suggest that you put in outlets everywhere and even put in an AC wire for future use (by you or future owner....it is a good item to aid in a sale.)

[lewster]

In my professional opinion, Romex has NO PLACE in a moving RV, just like it is against code for use in the marine industry! Romex is made for use in a stationary house. The continual bouncing of an RV will introduce work hardening to solid copper and it will be subject to eventual breakage.

I spend many hours each year tracing dead 120VAC circuits in RVs only to eventually find a broken solid copper conductor, often inside it's insulation.

The better alternative, and the one that I have been using for over 14 years on any RV wiring project or repair is stranded marine cable. It comes in all of the usual 'Romex' sizes yet is far stronger and much more supple than solid copper Romex. Plus, you get the added anti-corrosive properties of fully tinned strands within the insulation wrap.

Use 14/3 for 15 amp circuits, 12/3 for 20 amp circuits and always remember, you are protecting the wiring with your fusing or circuit breakers.....NOT the devices that they are connected to by matching the ampacity of the wire to the appropriate over current device.

[Melody Ranch]

Do what Lew says...he knows his stuff.

[GeocamperAS]

120 volt circuits in a trailer is no different than 120 volt house circuits.
All the 12 volt items in your trailer (lights, vent fan, furnace fan, water pump) are powered the battery when you are not plugged into 120 volts. When you do plug into 120 volts, all your 12 volt items are powered by the converter in your trailer that is plugged into 120 volts (converting the 120 to 12 volts).

The 12-2 you bought is correct.

14 gauge wire is used for a 15 amp circuit. (15 amp breaker)
12 gauge wire is used for a 20 amp circuit. (20 amp breaker)
Although overkill, se can use 12 gauge on a 15amp
BUT NEVER use 14 gauge on a 20amp.

I would install at least 4 branch circuits, example, one for the A/C, a second for 1/2 of the outlets, a third for the other 1/2 of the outlets and a fourth for a Microwave oven. I would use 12 gauge with 20 amp breakers.
Most A/C's and M/W's draw about 12 amps. If the voltage at the campground is poor, they could draw much closer to 15 amps. Therefore with a 20 amp you will have less of a change of a tripped breaker to deal with. Also divide the 2 house outlets planing on what "could" be used. A slow cooker in the kitchen and a blow dryer in the bathroom would blow the breaker if on the same circuit.

Make sure when you run the 12-2 through the trailer, any holes in the channels should have a plastic grommet so the sharp edge of the aluminum does not cut through the insulation of the wire.

Hope this helps

[GeocamperAS]

Originally Posted by lewster

Use 14/3 for 15 amp circuits, 12/3 for 20 amp circuits and always remember, you are protecting the wiring with your fusing or circuit breakers.....NOT the devices that they are connected to by matching the ampacity of the wire to the appropriate over current device.

When you buy bundled wire like Romex or BX you need to be careful what you ask for. Especially if the clerk selling it has no clue.

14/3 or 12/3 could mean 2 wires plus a ground (black, white and bare copper). But it could also mean 3 wires plus a ground (black, white, red and bare copper).
14/2 or 12/2 could be sold with or with out a ground.

You want a black a white and a bare copper.

[Airwave503]

Awesome, thanks you guys!

I'll get a 30amp receptacle just in case (I didn't realize you can just slap an adapter for a regular plug on there).

I'll go find some marine stranded wire. I go to a lot of bumpy places and I live in a very moist place.

I'll have all 20 Amp circuits since all my lights will be 12V and everything else like outlets, microwave, fridge needs the 20 Amp circuit.

I'll get all 12 gauge wire. Black, white and copper.

[lewster]

Originally Posted by Airwave503

Awesome, thanks you guys!

I'll get a 30amp receptacle just in case (I didn't realize you can just slap an adapter for a regular plug on there).

I'll go find some marine stranded wire. I go to a lot of bumpy places and I live in a very moist place.

I'll have all 20 Amp circuits since all my lights will be 12V and everything else like outlets, microwave, fridge needs the 20 Amp circuit.

I'll get all 12 gauge wire. Black, white and copper.

Actually, 12/3 marine cable is black/white/green as all of the conductors are insulated individually. Green is ground. You can also get 2 conductor marine cable and if all of your 12VDC circuits are 20 amp, 12/2 is what you will need. That is available in either standard colors of black(positive) and white (negative) or marine specification red (positive) and yellow (negative).

[TG Twinkie]

Many do not realize that the outlets most commonly sold in the big box stores are rated at 15 amps. The same goes for light switches commonly used in your home.
Read the labels on the packages.
For example; 20 amp outlets have two vertical slots, like those in your home. But one slot has a vertical slot. Looks like a sideways "T".
IMHO The hardware should be rated to handle the same current as the wire and circuit breaker that protects it.


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[TG Twinkie]

Meant to say horizontal slot.


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[DavidsonOverlander]

Airwave503,

If you haven't already done so you may wish to listen to the most recent edition of The Vintage Airstream Podcast as they discuss a similar question on the Nov. 14 Podcast (Episode 222).

[Airwave503]

Thanks Davidson,

I listened to the podcast and they don't share Lew's experience with solid wires failing. Realizing that my trailer will have pretty limited use for the next 15 years (until I retire and move in full time and that the marine stranded was 3X more expensive, I think I will stick with the 12/2 I got and just secure it really well.

Please don't ban me from your knowledge fountain Lew!

[PA BAMBI II]

Originally Posted by lewster

In my professional opinion, Romex has NO PLACE in a moving RV, just like it is against code for use in the marine industry! Romex is made for use in a stationary house. The continual bouncing of an RV will introduce work hardening to solid copper and it will be subject to eventual breakage.

I spend many hours each year tracing dead 120VAC circuits in RVs only to eventually find a broken solid copper conductor, often inside it's insulation.

The better alternative, and the one that I have been using for over 14 years on any RV wiring project or repair is stranded marine cable. It comes in all of the usual 'Romex' sizes yet is far stronger and much more supple than solid copper Romex. Plus, you get the added anti-corrosive properties of fully tinned strands within the insulation wrap.

Use 14/3 for 15 amp circuits, 12/3 for 20 amp circuits and always remember, you are protecting the wiring with your fusing or circuit breakers.....NOT the devices that they are connected to by matching the ampacity of the wire to the appropriate over current device.

Hi! I am intrigued by this answer to a post pertinent to what I am tackling right now in my '61 Tradewind: wiring.


I looked up this stranded marine cable, and it has great reviews. Happy to go this way instead of Romex, but have a few questions:


1) what size wire/circuit (15 or 20 amp) should I used for a regular Norcold 2-way fridge?
2) what size would I want to use for basic 12v circuits (lighting, water pump, etc.?)
3) what size would I want to use for the electric brakes?



Like I said, I am happy to have found this post. Thanks for sharing this information.


Ben

[lewster]

Originally Posted by PA BAMBI II

Hi! I am intrigued by this answer to a post pertinent to what I am tackling right now in my '61 Tradewind: wiring.


I looked up this stranded marine cable, and it has great reviews. Happy to go this way instead of Romex, but have a few questions:


1) what size wire/circuit (15 or 20 amp) should I used for a regular Norcold 2-way fridge?
2) what size would I want to use for basic 12v circuits (lighting, water pump, etc.?)
3) what size would I want to use for the electric brakes?


Like I said, I am happy to have found this post. Thanks for sharing this information.


Ben

To be on the safe side, I would use the 20 amp capable 12/3 gauge cable for all of your 120VAC circuits and 12/2 gauge cable for all of your DC circuits. This will allow the proper flow of power to all of your circuits, even if they require less then the 20 amp rating of the cable. Same for your electric brakes. Also, be sure to connect your power source with 10/3 from the covered port on the outside of your trailer into your breaker box.