RV outlet

Discussion in 'Electrical Forum discussion & Blog' started by rrcur, Jun 20, 2012.

  1. rrcur

    rrcur New Member

    Messages:
    14
    Location:
    Southern Maine
    My old house has an RV outlet (NEMA TT-30R) mounted on the outside of an exterior wall. Since I have no use for this, I'd like to remove this recepticle and use the circuit for other purposes.

    The raised printing on the recepticle says "Travel Trailer Use Only, 30A 125V." In the panel, there is a single 30 amp breaker that is clearly labelled "RV Outlet," and when I switch this breaker off, the recepticle is de-energized.

    So far so good, but here's the problem.

    The cable running from the panel to the recepticle has three wires (black, white, red) and a ground and is labelled E25682F (which is 10 gage, 3-wire w/ ground, direct burial cable). I had expected to see two wires and a ground.

    The black, ground, and white wires are connected to the back of the recepticle, and the ground is also connected to the ground screw inside the outdoor junction box. The red wire is not connected to anything, and appears to be just sitting in the box.

    Does this make any sense? It is possible that the previous owner just used whatever 10 gage cable he had lying around and that the red wire is not connected at the panel?
  2. Chad Schloss

    Chad Schloss Member

    Messages:
    329
    Location:
    USA
    sounds like that, or they thought ahead, in case someone wanted a 220v outlet for future use. kind of like wiring a ceiling light in your living room / bedroom with 14/3 just incase someone may want to install a fan/light kit there one day, the wire is always there.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,691
    Location:
    Cave Creek, Arizona
    The important thing is what about the OTHER end of the red wire. Is it also "just sitting" in the panel box? You can only tell that by LOOKING at it. We can guess what he did, but our guessing could get you electrocuted.
  4. rrcur

    rrcur New Member

    Messages:
    14
    Location:
    Southern Maine
    I plan to take off the panel cover to see if the other end of the red wire is connected to anything. I have a very high degree of respect for electricity, and I generally draw the line at working in (or even touching) the panel. I also triple check wires before I install a light fixture or junction box to make sure they're not energized.

    If the red wire is truly just along for the ride (unconnected at both ends), is it safe to just cap the red wire, ignore it, and treat the three-wire cable as a two-wire cable with only a hot, a neutral and a ground connected to the panel?

    I'd like to remove the RV recepticle and use this circuit to add one or two conventional duplex outlets on the first floor of my house. My approach would be to terminate the the three-wire cable at a new interior junction box and extend the curcuit from there with two-wire Romex.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,059
    Location:
    New England
    If the red wire is not connected, yes, it is safe to use that circuit for 'normal' outlets. since it is 30A, you could install 20A outlets rather than the more common 15A ones. Then, if you ever did want to power something that required higher current, you'd be all set. A 20A outlet will work with typical straight or 20A cords since one slot is T-shaped to accept either plug configuration.

    BUT, and this is IMPORTANT; unless you change the breaker ALL additional wiring must be the same gauge. The CB is protecting the wiring, and it must be matched with the wire. If you want to use say 12g wire, you'd have to also change the CB to at most a 20A one, or with 14g, a 15A breaker. It's okay to have heavier wire on a circuit, but NEVER smaller gauge. The extra wire (red) isn't a problem.
    Last edited: Jun 21, 2012
  6. rrcur

    rrcur New Member

    Messages:
    14
    Location:
    Southern Maine
    Ok, so I (carefully) took the cover off the panel, and the red wire from this cable is definitely not connected to anything. It just hangs straight down all by itself to about 3 inches above the bottom of the panel box and is capped with a wire nut. I re-traced the path of this wire from the panel entrance five or six timeswith my eye (and with a flashlight) to make sure i was following the right wire.

    As a final precaution, after the cover is back on, I guess I should flip on the breaker and test the red wire to make absolutely triple sure there's no current there.

    Thanks very much for the advice, especially about wire gauge.
  7. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    Thank the lord for cautious people who call their friendly neighborhood electrician. Guys like you keep us employed.

    The wire is capped in the panel, all is good.

    As for the code and ampacity of wire gauge, etc. I am nearly certain that you cannot have a 30 amp breaker protecting any general use circuits. A general use circuit is one in your house that has several outlets that have two vertical slots for the hot and neutral, and are protected by a 20 or 15 amp breaker. A 30 amp circuit must have a specific purpose, such as a window air conditioner, and can only have one outlet, usually not a duplex.

    You CANNOT be stringing this out as a 30 amp circuit and hanging 20 amp receptacles on it. And trust me, you don't want to wrestle with 10ga if you do not need to. Even 12ga is a pain. And expensive.

    You can exploit the existing 10ga for a 20 amp circuit featuring several 20 amp receptacles, and even extend it with 12ga, but you must protect it with a 20 amp breaker.

    I would make a point of using some white electrical tape and a sharpie in the box to mark both the hots as 20 amp max, and use a 20 amp breaker. Hopefully no knucklehead 30 years from now will be all confused.

    Sorry I cannot cite the code for you.
  8. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    I am just as certain as I can be that 30 amp circuits cannot be used as general purpose circuits in a home.

    One could have two 50 amp circuits in a three wire arrangement feeding all the outlets and lights in the house, except kitchen, bath and laundry, yes?

    There would be zero protection for anything plugged into those circuits.

    You are correct about re-purposing larger wire. A nice old lady bought a gas range to replace her electric. I took the 50 amp receptacle off the wire and using a huge box, installed a 15 amp outlet to juice her controls and timers on the new range. And changed the arrangement at the panel. Got lucky there, as an old panel had been gutted and the wire run thru a large conduit to the new panel. Easy to pull the large wire out of that conduit and replace it with 14 ga and tie it to the original wire in the old panel. Saved me crawling under the blasted house. And easily reversed.
  9. rrcur

    rrcur New Member

    Messages:
    14
    Location:
    Southern Maine
    Ok. Thanks. It makes sense that the 30 amp circuit can't be connected to a string of gereral use recepticles. I've already removed the RV recepticle because I have no use for it, it looks like crap, it's poorly connected to the wall of my house and it's a haven for yellow jackets. I'll probably just cap the wires,terminate the cable in a junction box in the basement and flip off the breaker until the next time I have an electrician around.

    I can't resist asking just one more question. If I use the correct wire gauge, am I prohibited from using this circuit, as it is, as a dedicated circuit for a large window air conditioner? The a/c unit probably draws in the neighborhood of 10 amps at 120 volts and has a conventional 15 amp plug. It has a tag that calls for a dedicated circuit.

    Just wondering.
  10. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    Ask, ask ask! You have a "large" window AC unit? That runs on 120v at 15 amps? I don't think that you do, I think you have a 240v unit that runs on 15 amps.

    Read the specs again.

    That said, you are well within your capacity to use this cable to wire it. If it is in fact a 240v unit, you need a dual pole breaker. Not a tandem, don't confuse the one with the other. As this is 10/3, you would (assuming I am correct) use the black and red to the two hot slots on the receptacle, and the bare wire would go to the ground screw. You can pull the white wire out of the buss bar and cap it with a wire cap and use a wire cap at the other end as well.

    Double check the current demands of the unit. Seeing as you are giving it a dedicated circuit, use a breaker in the panel that is no more than it needs. If the specs say that a 15 amp circuit is sufficient, then by all means install a 15 amp breaker. That is vastly safer than using a 30 amp breaker where it is not needed.

    Any way you figure it, you are using much more copper than is necessary, but you already have it. If I were installing from scratch a 240v 15 amp dedicated circuit for a window AC I would just run 14/2 NM (assuming NM is approved and you are ok with it) and mark the white wire at both ends red.

    And do not "just flip off the breaker" after you make the cable redundant. Turn off the breaker and remove the wire from the breaker, and cap it off, such that it is impossible that it could casually be re-energized.
    Last edited by a moderator: Jun 24, 2012
  11. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    But, as I wrote, if you change the breaker to 20 or 15 amp, you are OK.

    You can even have two circuits, seeing as you have 10-3.
  12. rrcur

    rrcur New Member

    Messages:
    14
    Location:
    Southern Maine
    The window air conditioner I mentioned is "large" in that it barely fits through the lower sash of my windows, and it's much bigger than the other unit I own. It is "surplus" from my office at work, so I've never hooked it up before. As I mentioned above, I assumed it was a 120V appliance becasue it has a standard, three-pronged plug (5-15P?). I just checked the plate on the unit, and it confirms this: Gibson Model GA L123K1A2, 115V, 12,000 BTU, cooling amps 11.2, Watts 1225.

    So my question remains, is it unsafe to connect this existing cable/circuit to, say, a dedicated 20 amp recepticle for use soley by this ac unit? If it makes a difference, the total cable run would be about 4-5 ft from the panel, since the window in question is on the first floor and almost directly above the panel in the basement.

    As I've mentioned, I'm not comfortable working inside the panel, so I'm looking for safe, code compliant modifications I can make (or not) outside of the panel.

    If what I'm proposing is a bad idea, that's fine. I'll give it up and move on to other things.

    Thanks again for the help.
  13. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    OK. No offense, but I am not assuming that you know a 120v plug from a 240v plug at a glance.

    Reading the plate, very good!

    Dedicated circuits with a single appliance attached are expected by code to have a single outlet. Not a duplex plug. One plug in a circle, nothing else can be plugged in. That is one thing.

    Being afraid of the electricity is a good thing. You may well live to a ripe old age!

    Not wanting to work in the panel? Is there any sort of master shut off? If you turned off the whole panel, it gets a good deal less hazardous. No experienced electrician would need to for a small thing like this, but there is no reason that you should not. Except that someone might need to hold a flashlight for you.

    What sort of box is it? Who built it? There are old and hazardous panels that should be replaced outright. Can you find any brand name on it? Most likely there is no problem.

    Is your house wired with non-metalic cable? Known popularly as Romex(registered trademark)? If so, the world is your oyster, nothing easier.

    14-2 is all you need. And a 15 amp breaker. Don't use a 20 amp breaker with 12ga. There is no upside benefit and it is a hazard. See the thread about the stolen wire just a few below yours. And 14ga is MUCH easier to work with.

    If you can drill a hole thru the bottom plate of the wall into an appropriate stud bay, things are very good. Cut a hole in the wall for an old work box and use a stiff rod ( a coat hanger) to reach from the basement up to the hole for the box, use that to pull the wire up. Staple the wire as close to the hole as practical and keep it tight to framing as you get it to the panel.

    Is the panel in your basement the only panel in the house? If it is, the white (neutral) wire and the bare (ground) wire each go to the neutral/ground buss bar. They are supposed to each have their own screw. Often there are not a lot of screws in older panels, and you might use the same one for both. A pro MIGHT install a supplemental buss bar, but most likely he'd just shove both under the same screw and call it good. Just be sure to torque the screws down well.

    If it is a sub panel then there must be two buss bars, one for each, and the neutral buss bar must be insulated from the panel. If this is a sub panel and the buss bars don't seem to be arranged as I described, hire an electrician to assess the situation. Sub panels with the neutral and ground mixed up causes electricity to be in all sorts of places in your house where it should not be and presents a significant hazard.

    But you almost certainly don't have that issue unless it is an older panel and a new panel was installed elsewhere as an upgrade.

    As I wrote, you need a 15 amp breaker. Are there any spare spaces? You could certainly pull out the 30 amp breaker. You could loosen the cable clamp and pull the 10-3 cable out of the panel completely, and route in your 14-2 in the same clamp. Just coil up the 10-3 and tape it up. Once it is pulled out of the box the code has very little to say about it. It could be declared "abandoned" and some inspectors would insist that it all be pulled out, but let's get serious. It is no hazard, don't worry about it.

    You can go to youtube and find videos about how to add circuits. Watch them, and then read the comments attached to them. A few youtube how-to videos are trash, but those all get hammered by real electricians and handymen who spot them for the trash that they are. You are considering a very basic and not frightening project. It really is not a big deal.
    Last edited: Jun 23, 2012
  14. Rich B

    Rich B DIY Senior Member

    Messages:
    283
    Location:
    New Jersey
    Leave the wire alone....use it just the way it is run. Black is hot...white is neutral. Leave the red alone and unused. If it makes you feel better put a wire nut on the red wire end in the panel . Change the breaker to a 20 or a 15 if you like and install a good quality recepticle that will fit the AC unit. A single is a good way to limit the circuit to just that AC unit. It draws 11.2 amps so your well under a 15 or 20 amp breaker rating....the wire is more than enough and a good 20 amp rated recepticle is fine...Get a single recepticle cover plate and your done....

    Working in your panel while it is live is not a good idea if your a novice.....My advice was simply what I would do and I am not a novice. If your worried about working in that live panel or about meeting code...get a licensed electrician....

    Don't make it harder than it is, and the answwers that are written on this forum are rediculous sometimes...

    The wire alone does not set the amperage you can draw on a cirucit....Everything on that circuit needs to be sized right but having wire larger than is needed does no harm....Use it and change the breaker and the outlet....


    I will probably get bashed for something being wrong or not to code but I expect it here.....
    Last edited: Jun 23, 2012
  15. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,534
    Location:
    North Carolina
    my advice also .
  16. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    If he is changing the breaker, he is working in the panel. Do look at what he wrote. The 10-3 does not actually go where he wants a receptacle. He still needs to drill a hole in the bottom of the wall and fish some wire up into the stud bay. Doing that with 14-2 is going to be lots easier than with 10-3. Lots.

    And certainly no loose conductors in a panel or box should be allowed without a wire nut to indicate that they are not in use and to prevent them getting live to current.
  17. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
  18. Rich B

    Rich B DIY Senior Member

    Messages:
    283
    Location:
    New Jersey
    Read my post.......I did not say changing the breaker was OPTIONAL.
    I did not say to work in the live panel if he is a novice.
    I DID say get a licensed electrician if he was concerned about doing it to code and safely...
    I never advise anyone to work in or on live electrical panels or eqiupment.
    I do it all the time but like I said.....I don't advise NOVICES or homeowners to do this work....





    Since neither you or I are there we cannot tell exactly what may need to be done to make this right.
    MR JW agrees with my post and thats more than good enough for me.....


    Have a nice day.....
  19. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,059
    Location:
    New England
    FWIW, when running a 20A circuit, it's perfectly alright to use 15A receptacles. The CB protects the WIRING, not the things plugged into it.

    While not the way we do it, in the UK, each thing plugged in has its own fuse or CB...the wiring basically gets an on/off switch, but not a CB at the panel.
  20. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,218
    Location:
    Houston, TX
    What is wrong with 12 gauge wire ?

    I would use 12ga. To run a air conditioner, and it would be less of a problem with voltage drop then 14ga.

    A 15 amp breaker may trip when the compressor starts with any Head pressure. A 20 amp breaker and 12ga. is the way to go for a air conditioner.

    Most window air units have current limits, but do not have Head pressure delay relays.

    What is unsafe about using 12ga over 14gauge ? Screw easier to work with.
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