Neutral/ground at sub breaker panel

Discussion in 'Electrical Forum discussion & Blog' started by Cubey, Aug 16, 2007.

  1. Cubey

    Cubey New Member

    Messages:
    78
    Location:
    Southern Arkansas
    I purchased a breaker box with 2 slots for a project I am working on for a portable outdoor 30 amp to 15 amp converter that features an outdoor breaker box with two 15 amp breakers leading to 2 duplex outlets with an in-use weatherproof cover, raised up off the ground by a stand. I will then plug in 12 gauge extension cords for extra amperage in my vintage travel trailer. This is my solution to the breaker question thread, but now I have a new separate question/problem.

    Anyhoo, the breaker box I purchased has the ground and neutral connected together. Is this normal for a sub breaker? Some websites I read say not to do it while others say its normal. Huh??

    If its not normal, how do I deal with connecting the ground? Do I splice the outlet's ground to the 30 amp service ground directly without going through the breaker's ground strip (which is very obviously also the neutral connection off to the sides) or what? That certainly doesn't seem right from what I read online since current going through ground has something or other to do with tripping the breaker.

    Can anyone clearify if its safe and normal for a sub breaker to have ground and neutral connected together, especially when it's going to be plugged into many different electrical systems. I need to know the universal way to wire the breaker box's ground & neutral in a safe fashion, if that is at all possible.
  2. Cubey

    Cubey New Member

    Messages:
    78
    Location:
    Southern Arkansas
    Figured it out for myself finally! Isolate neutral from ground in a sub panel. Looks like I'll be going back to home depot for a grounding bar to put in.
  3. Bob NH

    Bob NH In the Trades

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    What is a "portable 30 amp to 15 amp converter"? Are you using the subpanel to supply a couple of 15 amp outlets from a 30 amp breaker?

    Answers to your question:

    The neutral in a subpanel must be isolated from the ground.

    The usual practice is to have a ground bar separate from the neutral bar but you probably don't need a ground bar for two circuits (see below).

    The neutral bar is often mounted on an insulator and there will be a green screw, installed or furnished loose, that "bonds" the neutral bar to the enclosure. That screw is not used in a subpanel and must be removed if it is already installed.

    If the neutral bar is mounted directly to the enclosure (not insulated), then you will have to install an insulated bar for the neutral or provide another means to isolate the neutral.

    Then you will have to provide a ground point to connect the incoming and outgoing grounds to the enclosure. That could be a ground screw in the enclosure with the grounds all connected to it.

    Are you feeding the subpanel with a two-pole 240 volt breaker or a single 30 amp breaker?

    The outdoor receptacles will have to be GFI protected. The best way it to install a

    Are you running the wire from the main panel underground? UF or in conduit?

    Usual Practice:
    The usual practice with a subpanel is to run a 240 Volt circuit (from a 2-pole breaker) to the subpanel. If you want 15 amp circuits you would run #14 black and red (or two black) plus one #14 white plus a #14 green (or a 14-3 + ground cable) to the subpanel. Then you would run two separate #14 circuits (15 amp) to the outlets. You need only #14 because the neutral load cancels if both circuits are loaded.

    However, that won't work if the trailer is wired for only a 120 Volt supply.

    The way you have described your installation (30 amp circuit to subpanel) you will have to run #10 black, #10 white, and #10 green (or #10 cable such as UF) to the subpanel.

    Edit Postscript: You answered your question, a lot more succinctly than I did, while I was writing. I will leave this here in case there is information that may be useful to you.
    Last edited: Aug 16, 2007
  4. Cubey

    Cubey New Member

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    78
    Location:
    Southern Arkansas
    It will plug into 30A service at an RV park and there is a 30A breaker on at the hookup pedistal. The purpose of this is so I can make use of the 30A service without using a $5 "cheater" adapter which can be a fire hazard if misused either on purpose or accident.

    I need this for long term use however I didn't want to have to haul the trailer to someone to have a hole cut into it for a 30A inlet, nor have to pay that since people around here charge an arm a leg for the most basic things so I figured it wouldn't be cheap.

    I'm far from good at simple wood cutting so I didn't dare try to do that myself. This seems like the safest and easiest solution for doing it all myself. I will have that breaker thing to carry around but I don't see that as a big deal. Doesn't weigh much and can be stored easily.

    I really only need it when 15a isn't enough, which is what the trailer's electrical system is designed for. I will need the extra amperage mainly in winter when I will need to run a heater or two. This will provide me with safe extra amperage for that. I suspect a single 1500W heater will keep me plenty toasty but I say "or two" since.. well, you never know! A second heater could be run at a lower setting (ie: 600W) as not to max out the hookup. Also, there will only be one duplex outlet per breaker so there definitely won't be any overloading. A single extension cord will be plugged into it and run into the trailer. In the case of needing two heaters I'd have to run another cord as well or just use it on a lower setting while plugged into the trailer's electrical system. As long as I count my amps I'll be fine though I don't wish to put much strain on the trailer's electrical system.

    This is actually also useful should I find an RV park or campground that lacks 15/20A outlets. I can haul out my converter and get separated, breakered 15A power without using a cheater adapter.

    I was thinking about that but wasn't sure. I guess I will do so.

    Yes, that is what I will do. Home Depot has a #10/2 cable rated for outdoor use (not UF, it was black and insulated) that is flexible and the guy said that would be fine to use for wiring up to a breaker. I will only need about 4-5 feet of this as converter will be kept right at the hookup pedestal and 15A extension cord(s) run to the trailer from it's outlets.

    This may seem like a big waste of time an effort when I should just get a 30A system built into the trailer but eh, this seems kind if easier for me so thats what I went with. Easier, except I have to haul out a special convert box every time. Oh well! *lol* I could easily have 30A service put in later and reuse the breaker box and such if I find this to be too much trouble but I don't think it will be for my planned usage of it.
  5. Cubey

    Cubey New Member

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    78
    Location:
    Southern Arkansas
    Here is a photo of it so far. It will have a big #10/2 (plus ground) cable coming out the bottom of the breaker box of course but this how it'll look aside from that. The purpose of the stand is to keep it from falling forward or sideways. It will be braced against the electric hookup pedestal so it won't be able to fall backwards. A simple $2 lashing strap going around the pedestal and stand will keep it up just fine should there be some gusty winds.

    The stand legs are just leftovers from some poles I got used for making a rope & pole awning using a tarp. The stand is clamped in place and mounted to the back of the breaker box with screws & nuts.

    The weatherproof in-use outlets are attached to the box via screw in 2" nipple. I need to seal up all the caps and such before I start wiring it up.

    [​IMG]
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

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    What you have is a death trap in the making. When you get to the RV park find the space that you need.
  7. Cass

    Cass Plumber

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    Ohio
    Could you expand on that statement.
  8. hj

    hj Moderator & Master Plumber Staff Member

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    trailer

    Either I am misunderstanding, or you made the project more complicated than necessary. It makes no difference whether the park has a 30 amp, or 100 amp at the connection, as long as the wire to your panel will handle it. YOUR breaker in the trailer then limits how much of that power you can utilize. It looks like you have to run an "extension cord" through the door to your subpanel.
  9. jwelectric

    jwelectric Electrical Contractor/Instructor

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    To understand what is being talked about here one would need to take a look at this thread along with the one we are in now.

    It seems that this is going to be a Camper used for full time occupancy and more than what the unit is designed for is going to be used at one time.

    These campers are set up from the factory with a distribution panel that is designed for the loads in the unit and it seems to me that the owner is wanting to add things that were not originally part of the unit ie; heat and AC.

    As has already been pointed out there will be cords passing through floors, walls, windows or doors which is a very big NO, NO!!!

    Instead of doing something to help this guy out anyone giving him help is only helping him burn his unit to the ground and I hope no one is inside when this happens.
  10. Cubey

    Cubey New Member

    Messages:
    78
    Location:
    Southern Arkansas
    Thats the thing. The wire between the 15A inlet to the panel is about 14 gauge. The insulation seems to lack any markings but its definitely not 10 gauge. In the 60s trailers came with 15A electrical systems, unlike now where they come with 30A or 50A. It would be a real fire hazard to use a cheater adapter which adapts a 30A outlet to 15A and runs through a 15A extension cord and plugs into a system designed for 15A only.


    I guess I'm not understanding the problem with running in an extension cord. Whats the harm?

    It will be entering the trailer though a plastic dryer vent. When I removed the gas furnace that was missing parts and generally beyond repair, I first put in a small catalytic heater (which lacks low oxygen sensor so I want to use that sparingly) which requires a high pressure propane supply so I had to run a dedicated high pressure propane hose in so I put in a dryer vent with a hatch next to the entrance door and ran in the propane hose.

    I can also use this for running in the extra extension cord. It will have no pressure on it such as a door or window and will not be bringing in any water when it rains. It enters through the dryer vent and into a cabinet. I simply run the cord out of the cabinet and I have the added amperage I need. I don't see how that would be unsafe or a fire hazard.

    Here is a photo of the dryer vent with the propane hose entering through it.

    http://img.photobucket.com/albums/v222/illiop/dyer_vent.jpg

    Seems perfectly safe to to me to do it in this fashion. I will be installing GFCI outlets for the converter and it will be double breakered (the 30A hookup breaker plus my 15A breakers). The box will be kept off of the ground so it won't be sitting in a puddle of water. I guess I'm not understanding the problem. I do see how I've greatly complicated things but my only solution would be to have someone cut the hole in the trailer for the 30A inlet. Seems like nothing in contrast to what I'm doing, I guess. Wish my logic didn't complicate things as it does.. But in any case I honestly don't see how this idea is dangerous. If you feel it is, please explain it.
    Last edited: Aug 17, 2007
  11. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    The biggest danger lies with what you can't see as a danger.

    You must first learn that what works is not always what is safe.

    The fact that you have changed the heating unit for a high pressure unit is a big danger in and of itself.

    Now you are wanting to start adding cords through holes in the wall to add to the current load of the camper.

    Unless you are planning on having this camper tested with the remodel work you are doing I would highly suggest that you stop.
  12. Cubey

    Cubey New Member

    Messages:
    78
    Location:
    Southern Arkansas
    It seems you are completely misunderstanding what I'm doing.

    Regarding propane, I didn't "change" the pressure from high to low. The original furnace ran on the low pressure propane supply lines. The heater I bought needs high pressure as it was designed for 1lb bottles, but of course can safely run off of a bulb cylinder (kept outdoors, of course!) with the proper hose which is what I have done. The heater is connected to a bulk cylinder located out on the tongue of the trailer and the hose runs in to the heater. It is completely independent of the low pressure system of the trailer which the stove and fridge run off of. Perfectly safe.

    Now about the electrical stuff. I will NOT be adding any more load to the trailer's electrical system. Thats why I will be running in an extension cord, for the specific purpose of NOT adding excessive the load to the trailer's electrical system. The extension cord will have a heater plugged directly into it, completely separate from the trailer's electrical system. I will not be overloading anything anywhere. The trailer will have it's electrical system plugged in to one 15A outlet and the extension cord I run in will directly plug into a heater while being plugged into another, seperate circuit 15A outlet. Think of it as plugging in two extension cords on two seperate circuits in a house and using them. Thats bascually what I will be doing, except one of the extension cords plugs into the trailer's electrical system for its original 15A service. The other one will feed a heater. However the extra extension cord is plugged directly into the heater. I will not be combining two extension cords into the trailer's electrical system to pull 30A out of a 15A system which seems to be what you think I will be doing. I will simply be using an extension cord that is run into the trailer for plugging in a heater. I will get a 12 gauge cord so it can handle the load well.

    The only other solution I can come up with is to mount a 30A inlet box on the back of the trailer and have the box sticking out of the back instead of being flush on the side. It would be the same thing as I'm doing now except it would be built in. (Not sure why I didn't think of that before...) I suppose I could try to do that but really it would be the same difference as using an outdoor converter. Would mean less cords to deal with is all. Humm.. now I think I may do that. *grumbles* I'm about the worst in the world at making descisions.
  13. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    Cubey

    Once again, What you are doing is building yourself a death trap.

    You are taking appliances that are not approved for what you are using them for and trying to install them in a tender box.

    The best and only advice I have for you is to either live with what you have or trade it in for something that you want before you kill yourself.
  14. Cubey

    Cubey New Member

    Messages:
    78
    Location:
    Southern Arkansas
    You are being very vague. You are not explaining anything. A statement that its a deathtrap tells me nothing about the WHY it is. Anyone can make a statement that something is dangerous but without the explaination as to why it is dangerous, how would anyone understand and not do it? Tell me WHY and WHERE it is dangerous.

    And what appliances are you talking about? A heater? Since when is a 1500W heater not supposed to be used on a 15A circuit?
  15. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    Well let's see how this works out.

    It is a resistive heating load that is to be calculated at 125% and I do believe that this will come to 15.625 amps. Now let’s add a voltage drop from a drop cord and wonder where it will be?

    The NEC is a bare minimum safety rule book and it states;

    ARTICLE 400 Flexible Cords and Cables
    400.8 Uses Not Permitted.
    Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:
    (1) As a substitute for the fixed wiring of a structure
    (2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors

    Should I run into something like you are talking about doing in my jurisdiction there would be a power failure throughout the park in which this was found.

    Should a fire start and the insurance people find what you are describing then I doubt very seriously there would be a pay off.

    Should a fire start in your unit that caused damage in other units I do believe that you would be held liable.

    As to the new gas unit, was it purchased from a RV dealership or off the shelf at the big box store? There are some listing issues that would need to be addressed.
  16. Cubey

    Cubey New Member

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    78
    Location:
    Southern Arkansas
    Lets look a bit deeper into the NEC code you referred to. You put in bold 400.8 Uses Not Permitted. but you completely ignored the following line: Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following ....

    Now lets look at 400.7:

    Take note of number 3 and 6 which I placed in bold.

    According to number 3, it says portable lamps, signs or appliances. A 1500W heater is a portable appliance which would allow for flexible cable to be used on it. I would assume that means its power cord but that is what an extension cord is, just an extension of the power cord so that would mean that a long, flexible extension cord is fine to use on a heater. That doesn't really clarify the "though a wall" issue however.

    But..moving on to number 6...

    According to the list at http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9879 a recreational vehicle is considered "utilization equipment" which would allow flexible cable to be used to "facilitate frequent interchange" as mentioned in NEC 400.7.

    What I get from that is 400.8 says you absolutely can't:

    (1) As a substitute for the fixed wiring of a structure
    (2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors

    Unless specifically permitted in 400.7, flexible cords and cables shall not be used [for the items listed above]".

    400.7 says you CAN use flexible cable for "utilization equipment" and the link above I provided states that an RV is "utilization equipment".

    So the NEC code seems to state that its perfectly fine to use flexible cable through a wall.

    Also, I found out today that is how they make RV 30 amp inlets. I thought they had a fixed male socket but it turns out they put a #10/2 flexible cable with a male plug inside of a compartment with a hatch cover which is what you plug your 30amp cord into, not a fixed socket like I thought. So your argument kind of just flew out the window about it being dangerous and against NEC code to run flexible cable though a wall. They do it on a daily basis in the US for manufacturing RVs at this very moment and its in keeping with the NEC code.

    11 in 400.7 may also apply but I can't seem to locate 527.4(B) and 527.4(C) in the NEC code online.
    Last edited: Aug 17, 2007
  17. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
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    Location:
    NY State, USA
    Cubey, MAN, you are fishing, without bait.

    Nice try on all fronts but every argument is baseless.

    1) Flexible cords CANNOT be run through walls. Regardless of what you think you found you did not find any exemption for this rule. Mainly because there is none.

    2) Your "RV cord through a hatch theory" is totally WRONG. This is NOT a cord through a wall. It is a cord through a SPECIFICALLY designed hatch with a notch for the cord.


    Over the many years of coming to boards like this has taught me a few things. One of those things is recognizing when someone makes a statement like "Anyone can make a statement that something is dangerous but without the explaination as to why it is dangerous, how would anyone understand and not do it? Tell me WHY and WHERE it is dangerous.". This is almost always an indication that someone is fishing for the answer they want to hear. If they don't get that answer they call foul because they didn't get a full and detailed explanation. Sometimes a full and detailed explanation is quick and easy to put into words. Sometimes a full and detailed explanation is not worth it. Sometimes it can be well over the head of the average lay person.
    Sometimes folks just need to be told "DON'T DO IT", "THIS IS DANGEROUS", and they need to simply accept that.
    It's not like we are making out on this stuff. It's not like by telling you this our brother-in-law who is an electrician as well is going to get the job.
    We say this stuff because we know better, not because we will gain anything from it.
    This is why it amazes me when folks question us up and down the block when we say not to do certain things. Sometimes code is just CODE!
  18. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
    North Carolina
    Sorry big guy but your thinking is very flawed. There is no relief to allow a cord to pass through a dryer vent for a RV to be found in Article 400.

    Yes a RV is allowed to be cord and plug connected but it is also done in a UL approved manner.
    The site that you posted also states that an Industrial substations rule 1910.302(a)(1)(vii) but I can’t for the life of me remember seeing one cord and plug connected, can you?

    No the code clearly states that you can not run a cord through a wall from the outside to the inside to plug in an electric heater.

    First it is not my argument but the argument of the National Fire Protection Agency that you are trying to buck.
    No they don’t do it on a daily basis anywhere in the US. What they do in RV manufacturing companies is install a system that has been tested by a third party and install a system that has been approved and listed for the use.

    There is a very good reason why you can’t find 527.4 (C) and it because there is no 527.4 (C).
    The Article that governs RV is 551 and 551.44 is the rule for the electrical supply to the RV.
    551.44 Power-Supply Assembly.
    Each recreational vehicle shall have only one of the following main power-supply assemblies.
    (A) Fifteen-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(A) shall use a listed 15-ampere or larger main power-supply assembly.
    (B) Twenty-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(B) shall use a listed 20-ampere or larger main power-supply assembly.
    (C) Thirty-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(C) shall use a listed 30-ampere or larger main power-supply assembly.
    (D) Fifty-Ampere Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(D) shall use a listed 50-ampere, 120/240-volt main power-supply assembly.

    551.45 Distribution Panelboard.
    (A) Listed and Appropriately Rated. A listed and appropriately rated distribution panelboard or other equipment specifically listed for this purpose shall be used. The grounded conductor termination bar shall be insulated from the enclosure as provided in 551.54(C). An equipment grounding terminal bar shall be attached inside the metal enclosure of the panelboard.
    (B) Location. The distribution panelboard shall be installed in a readily accessible location. Working clearance for the panelboard shall be not less than 600 mm (24 in.) wide and 750 mm (30 in.) deep.

    As you can see you have missed it by a long shot.

    If you are going to fix the RV then do it right or not at all.
  19. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    Sorry Petey you posted while I was working, Well put!
  20. Cubey

    Cubey New Member

    Messages:
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    Location:
    Southern Arkansas
    Baseless?! That is the NEC code! You are the one who brought up the NEC code 400.8 and when I point out what it ACTUALLY says, you argue with the very code you mentioned. You have to be kidding me!! You make an argument and when it bites you in the butt you disregard it? I see how it is. You don't seem to know what in the world you are talking about! Yes, code is code. And the code says its allowed! Thats a code YOU pointed out to ME.

    Cables *CAN* be run through walls. The NEC code says it CAN and you just AGREED that it can be when it goes through special hatches or what have you. In the same breath you say that it's never okay to do it no matter what and then say its okay so long as you use special parts. HUH??

    What in the world have I already said about running the extension cord into the trailer? It will be going through a dryer vent with protects the opening and plugs from rain. That is exactly what the special RV hatch does. The dryer vent will do one better, the outlet on the extension cord will be far inside of the trailer out of possible wetness!

    People who accept things people say without question cannot think for themselves and have no clue about anything. An intelligent mind wants to know WHY something is so. That is called LEARNING. You cannot simply tell someone not to do something without telling them WHY. You do not teach them anything. You merely command them.

    Either you are full of it or you simply have a different definition of "running cable through a wall" than I do. I don't wish to simply drill a hole and run a cable through it. I wish to feed an extension cord through a hooded dryer vent (no actual dryer hooked to it!) which protects the opening from rain. Does as good of a job if not better than an RV 30A inlet hatch.

    I am arguing with your statement because you are not making any sense what so ever. You claimed it was dangerous and what have you. I ask you why. You say its against NEC code and provide me with 400.8. When I point out what 400.8 says that you skipped over, which says to refer to 400.7 and 400.7 says its ok, you completely disregard the NEC code altogether!

    I know an electrician that I will ask about this. I was trying to avoid asking him the favor but it since you are so completely involved in trying to be right no matter what I say will ever be right with you. I have to disregard your argument that completely ignores the NEC code 400.7 that I have pointed out to you.

    You have done nothing to help me. All you have done is argue with me and tell me I'm doing it wrong. You have not once actually given me any actual help or advice. You merely criticized me. That is not helpful. That is just rude.

    I will post the results of what the electrician says about both running in an extension cord and also the safety of the converter box I built. If he says its unsafe I will figure out something else. However, he will have the decency to explain WHY its dangerous so I don't make the mistake again some day and not just tell me not to do it. If I don't know what I'm doing wrong specifically how can I not do it in the future? Apparently that doesn't matter to you. you just want to order people around and not actually teach them anything.
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