50 amp, 240 volt hookup without equipment ground

[mikestock]

My son has purchased a lake house and we found a 50 amp RV plug. I checked it out and it has 120 volts from each leg to neutral and 240 volts between hot legs. The problem is that there is no ground wire attached to the round ground receptacle. I can see no easy way to remedy this without drilling through a brick wall and pounding a rod into the ground. I would be okay doing this if it were my own house. Also, I probably won't be using the hookup that often

Am I taking a great risk by using the outlet, as is, without a ground?

[Learjet]

Dave H M wrote:
Since we are off and on a tangent - what learjet posted is fool proof. i have one installed on my service box that is marketed by Square D, since that is the brand of my service.

google them up and read. If we had a lever to work everything this world would be interesting. :W

it is impossible to backfeed with the lock out device.

Obviously someone can defeat almost anything, if they screw round with it enough.

Thanks, a voice of reason 🙂

[Dave_H_M]

Since we are off and on a tangent - what learjet posted is fool proof. i have one installed on my service box that is marketed by Square D, since that is the brand of my service.

google them up and read. If we had a lever to work everything this world would be interesting. :W

it is impossible to backfeed with the lock out device.

Obviously someone can defeat almost anything, if they screw round with it enough.

[westend]

Mike
"photo not found"

[mikestock]

This is what they installed. Also an outside mounted male, weatherproof, plug .

[myredracer]

mikestock wrote:

... you need a transfer switch that is CSA or UL listed & labelled and it must be installed in accordance with the NEC (or CEC)...

If you are referring to my use of the DPDT description; This installation was done by a licensed contractor who purchased a permit and had it inspected. The switching device is four breakers with a mechanical interlock which closes two breakers when it opens the other two. Maybe my DPDT description was misunderstood.

Great to hear it was done by an electrician and an inspector passed it and it's not any kind of ordinary DPDT switch! Even licensed electricians can get sometimes get it wrong as anyone who has had or read about getting 240 volts into their 30 amp RV would know. I understand many (all?) states require generator setups to be permitted and inspected by the AHJ.

The breaker mechanical interlock ("slide bar") lockout like in Learjet's post may be approved and passed by an inspector but these things are awfully easily to defeat or remove intentionally or otherwise. There are numerous styles/versions of it. I'd rather see a manual transfer switch with a single handle.

mikestock wrote:
If I were a lineman, out there trying to restore your power I would be very uncomfortable, knowing there were 20 customers down the line with these self installed devices.
I know you feel comfortable with your installation, and it appears safe, but would you feel the same about the other 19.

If there's one thing that strikes fear in the hearts of linemen and electrical inspectors, it's the possibility of a backfeed.

[mikestock]

If I were a lineman, out there trying to restore your power I would be very uncomfortable, knowing there were 20 customers down the line with these self installed devices.
I know you feel comfortable with your installation, and it appears safe, but would you feel the same about the other 19.

[Learjet]

interlock device for your house main panel, easy to install and safe. This is GE's device made for the panel. Turn off what you don't want to feed with generator.

IF you google there are devices for just about any main panel.

here is my panel

[mikestock]

If you're going to set up something so you can switch a load(s) between the power company and a generator, you need a transfer switch that is CSA or UL listed & labelled and it must be installed in accordance with the NEC (or CEC). Doing otherwise can create a serious safety hazard not only for a user but also the utility co. working on their equip. (You can't ever use an ordinary double pole switch).

If you are referring to my use of the DPDT description; This installation was done by a licensed contractor who purchased a permit and had it inspected. The switching device is four breakers with a mechanical interlock which closes two breakers when it opens the other two. Maybe my DPDT description was misunderstood.

[myredracer]

If you're going to set up something so you can switch a load(s) between the power company and a generator, you need a transfer switch that is CSA or UL listed & labelled and it must be installed in accordance with the NEC (or CEC). Doing otherwise can create a serious safety hazard not only for a user but also the utility co. working on their equip. (You can't ever use an ordinary double pole switch).

Some info. with illustrations here.

[mikestock]

There is a reasonably simple solution. I had an electrician rewire my lighting receptacles, including my fan for the central natural gas furnace and the 120v supply for the gas range. He carried the feeder through an adjacent 50 amp DPDT breaker box and ran 30 amp wiring to an outside box with male setup similar to the 30 amp input on a small rv. I also have a natural gas water heater, so my ac needs and minimal. The only things I can't run are the central air or clothes dryer. I can even run the microwave or clothes washer if I carefully allot power.

I simply plug my 30 amp extension cord to the plug from my twin 2000 Hondas, go inside and reverse the DPDT breaker box switch. This way I'm either feeding from the generators or the power company. No way for the two to ever meet.

Whenever the outage ends I throw the switch the other way. I have one isolated receptacle that comes directly from my outside power box. I plug a radio into that receptacle and turn it loud enough to wake us up. When the radio comes on, I know the power is restored.

[CA_Traveler]

bucky wrote:
I found the same thing on our new to us house. I put it to a meter and knew then it was something screwy. Since I want to live a little longer I called an electrician. Same deal, backfeeding a gen set. No transfer switch, but had breakers labeled generator.
My original concern was if it was going to burn down my 5er if plugged in. The way the power goes out around here somebody could have died. The PO was an engineer of some kind, scary.
It had a good ending. Turns out the electrician is also a Generac whole house dealer. Got one coming, and he will install a 50A plug for the 5er as well.
Retired life is good.

Great post.

On another board a moderator posted information about how he backfeed a home with male to male plugs. I called him out about posting this type of information and he never responded.

Folks it's easy to put in a plug and with a male to male plug feed your house. BUT ITS ILLEGAL AND DANGEROUS AND POTENTIALLY LIABLE FOR YOU TO DO SO.

Transfer switches and equipment to switch your house to a generator are not cheap but it this is what you need then do it correctly. Then do so with safety considerations.

[bucky]

I found the same thing on our new to us house. I put it to a meter and knew then it was something screwy. Since I want to live a little longer I called an electrician. Same deal, backfeeding a gen set. No transfer switch, but had breakers labeled generator.
My original concern was if it was going to burn down my 5er if plugged in. The way the power goes out around here somebody could have died. The PO was an engineer of some kind, scary.
It had a good ending. Turns out the electrician is also a Generac whole house dealer. Got one coming, and he will install a 50A plug for the 5er as well.
Retired life is good.

[myredracer]

On bonding:
Electrical bonding is the practice of intentionally electrically connecting all exposed metallic items not designed to carry electricity in a room or building as protection from electric shock. (Wikipedia)

Grounding & bonding requirements can vary between the CEC and NEC and local AHJ. Current code editions and local AHJs should be always be consulted. Proper grounding reduces the risk of shocks and fire and must be done correctly.

In a non-detached building, a contiguous and correctly sized ground conductor is required to any sub-panel. A sub-panel ground and neutral bus bar cannot EVER be interconnected. A detached garage may be considered part of the main house or building if it is physically connected by a breezeway (or similar).

For a sub-panel in a detached building, a ground conductor to it is not required but must have the neutral and ground interconnected in the sub-panel. A ground conductor can be run to the detached building but in that case it cannot have the neutral and ground interconnected. A ground electrode(s) is required in a detached bldg. in both cases. If there is a metallic pipe(s) between the main & detached building, you need to avoid multiple return ground paths.

Installing ground conductors correctly ensures that a fault (short) to ground in a feeder to a panel or downstream of a panel will trip the branch circuit breaker or feeder breaker (depending on where the fault is). Installing bonding conductors correctly minimizes the risk of different metallic items within reach being at different voltages. In Canada, there cannot be a ground conductor to a building housing livestock to avoid "tingle voltage" - not sure about the US.

Grounding for pedestals in an RV park has been the subject of debate and disagreement in the US for some time. The 2017 NEC will eliminate any further possible confusion and not require a ground electrode at a pedestal. IMO, a ground rod at each pedestal should be req'd considering how well (not) electrical systems are maintained in many CGs. As a side note, NFPA is also proposing that a new RV park must have 40 percent of pedestals with 50 amps, up from the current 20 percent.

[DrewE]

Harvey51 wrote:
I wired my garage according to the unofficial wiring code book. The sub box ground is a heavy plate buried in the ground (the rod couldn't be pounded deep enough). The only explanation I could find for not connecting ground to ground or neutral wires from the house was that someone might accidentally dig up the cable to the house and cut just the ground and neutral. Is there a more likely scenario that would cause a problem in the garage or RV?

"Bonding" is another word for connecting, right?

Bonding, in this case, does mean connecting neutral and ground together--more specifically, in one spot, at the main panel.

Bonding and grounding/earthing are related, but serve somewhat different purposes. The neutral line is bonded to the safety ground to provide a low impedance return path for current from the chassis of whatever is attached to the circuit, so that a fault will safely go back that way (and, if the fault is severe enough, cause the breaker to trip and shut off power) rather than through your body when you touch the device. This works independently of an actual earth ground.

Tying the neutral (and safety ground) to a grounding rod serves to keep the overall voltages in the system in line with earth potential so you don't get shocked; without it, particularly in large distributed power systems, the voltage levels could float rather far from ground potential.

For outbuildings with their own panels, there are two basic options permitted by the NEC: either the connection to the outbuilding can be made with no ground connection (a wire or metallic conduit or metal water pipe or similar) and the service at the outbuilding treated more or less as a standard service entrance with neutral and ground bonded together at the outbuilding panel; or the connection can be made with a proper ground conductor of some sort (usually a wire) and the panel in the outbuilding must not have ground and neutral bonded. In either case, the ground at the outbuilding generally has to have an earth connection to a grounding rod.

The reason for not bonding neutral and ground at the outbuilding is that in some fault conditions (such as an open neutral between the outbuilding and the main building) it can cause ground connections to be current carrying and lead to all sorts of problems, particularly with other common grounds (such as metallic conduit, cable TV coax connections, etc.). It also makes for parallel current return paths that can cause other lesser difficulties.