Tiny House on wheels electrical wiring

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  #1  
Old 04-22-19, 09:31 AM
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Tiny House on wheels electrical wiring

Hi! I am struggling with a electrical issue I am hoping a experienced electrician can answer. I built a tiny house and install a 100 Amp electrical box. I have the house wired up like a normal home with serval different breakers. On the outside of the tiny house I install a 50 Amp RV box and a 30 Amp RV box.

I wired the 50 AMP as the main power coming into the panel. I installed deadman switch for the 30 amp box to a 30 amp breaker to use with a generator during a power loss.

The house has not been moved to the final location so I am limited to power by a generator (Honda 2000i) and a 20 AMP outlet on a GFI. For testing purposing, I made two pig tails to connect the 20 amp to both a 30 and 50 amp pig tail. If I use the generator, both 30 and 50 amp services work as advertised. If I connect to the GFI, it pops even with all breaker turned off.

The only thing I can think of is grounding. Does anyone know of conditions that would cause this? I was told the house grounding is enough to support the junction box but just in case I have a heavy duty grounding wire ran to the frame.

Also I am not sure why, but both nutueral and ground are on the same bus bar. I have read where its ok if its the first service entry but must be separated if not. Would the generator be consider a first service entry but the GFI a second? Anyone with experience on this condition that can chime in would be great appreciated! Thank you so much!
 

Last edited by ray2047; 04-22-19 at 01:11 PM. Reason: Add paragraphs.
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Old 04-22-19, 01:14 PM
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Welcome to the forums.

You will need to unbond the generator. Currently the neutral and ground are connected at the generator.
What make and model generator are you using ?
 
  #3  
Old 04-22-19, 04:56 PM
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Hello and thanks! It’s a Honda EU2000. So your saying if the generator was unbound, it would have the same problem? I am trying to get the plugged power to behave like the generator as it seems to be working correctly.
 
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Old 04-22-19, 09:32 PM
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I am tring to fully understand your setup. Where is the power for the 20A GFCI power coming from, the generator or from a home or other building?

If it's from a building then the neutral and ground would be bonded (connected) at the main panel. Therefore any voltage present on neutral or ground would be the same at that connection point and also relatively small. However some additional voltage will be present at the neutral terminals of your GFCI because of currents drawn by lighting and appliance loads through the building's neutral wires. The ground wires on the other hand should not have any current drawn through it that would produce a voltage. Therefore, if the neutral and ground are connected in the main panel of your tiny house, a current will flow and go though the neutral terminals of the GFCI. But since no current is flowing through the GFCI hot terminals, this unbalance will trip the GFCI.

So if you want to power a load through a
the GFCI outlet, you cannot connect a ground wire to the neutral "Load" output terminal of the GFCI because it will very likely trip (as well as not meet code requirements).
 
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Old 04-23-19, 03:27 AM
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Yes I have (2) power options at the moment. 1st is the generator and 2nd is the 20 amp GFI coming from a building. Only the gfi is tripping and generator is working fine. So per you write up, is it as simple as just discounting the main ground or would I need to remove the ground wire for each breaker in the panel and only leave the neutral connected? Or should I go to the 30amp to 20 amp pig tail and just connect the power and neutral and not connect ground? Thank you for responding!
 
  #6  
Old 04-23-19, 05:09 AM
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You need to hook up the main panel in the tiny house as if it was a subpanel in your main building. This means that you need a neutral bar that is isolated from ground (typically this in done by removing a bonding screw that goes through the neutral bar and into the back of the panel housing).
A separate ground bar is needed for the ground wires. The manufacturer of the panel makes ground bars for the panel if they come didn't with it originally.

If you eventually have the tiny house connected with it's own service from the power company, then the bonding screw would need to be replaced.
When using a generator, if the generator's neutral is not connected to the generator's ground internally, then the bond screw in the panel should be present. In most generators the neutral is already bonded to its own ground.
 
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Old 04-23-19, 05:11 AM
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Ok thank you! I am going to give this a try today and see what happens. I much appreciate your experience!
 
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Old 04-23-19, 05:13 AM
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For a mobile home you should keep the ground and neutral separate in the panel, which means keeping the ground and neutrals on separate bars and removing the bonding screw. The ground should bond to the panel box and also to things like the chassis if it's metal.

When you have electrical service installed at the final site, the power company will install it to a pedestal with a main breaker, which is where your ground-neutral bond will happen. You then run a four wire feeder cable from the pedestal to the mobile main panel, still keeping ground and neutral separate. Both the pedestal and the tiny house location should have earth grounding in the form of grounding rods and bare #6 copper bonded to the respective ground buses.
 
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Old 04-23-19, 06:26 AM
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Just went to look at the box per your instructions and it appears this box is setup to be a main panel. At the top of the box is as expected with a neutral connection and also has the green bond screw to bond to the panel box. The left and right side of the panel is the neutural/ground bar and is tied togeather with star screws and not a just the green screw. (Creating a n shaped single bar) I gues this box assumes this is the first service entry and no need to separate neutral and ground. Could I simply remove the ground wires for each breaker from the bar and let the main breaker ground coming off the building through the GFI service as a ground? Same for generator, let generator ground service for the sub panel. Or could I take all the grounds from each breaker and twist them togeather and create a separate ground with the separate heavy duty grounding wire I have installed?
 
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Old 04-23-19, 06:28 AM
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You remove the bonding screw to isolate the neutral bus from the panel box. You'll also need to buy an add-on ground bar which screws directly to the metal box and move all the ground wires to that.
 
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Old 04-23-19, 07:33 AM
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Thanks Ben! Looking into that now.
 
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Old 04-25-19, 08:23 AM
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Hi All! After doing the recommendations above, I still had the issue with the GFI popping. I have completely separated the ground from the neuteral by installing two new add on bars and removing the neutral bar ground screw. But..... I did learn something which gives me hope you know what is going on. Back story... Tiny house will be powered by either 30 AMP plug with generator or 50 AMP plug to box connected to meter. At its temporary location, I have access to 20 AMP GFI connected to a building and a Honda EU2000. I wired electrical box as you would a home first service entry. When I ran the generator, the service worked. When I plugged in 20 Amp GFI, the GFI popped. I have a 30 amp and a 50 amp RV box on the outside of the house. I built a 20 amp to 30 amp pigtail and a 50 amp to 20 amp pigtail. Per the tread above, it needed to be treated as a junction box and neutral needs to be separated from ground. Installed two new ground bars and separated out. It was still popping. This is obviously a ground problem so I decided to disconnect the ground from both the 30 amp and 50 amp breaker and it works! So there is contention from gound coming from GFI and the gound I created at my junction box but the generator doesn’t care. What is the reason or this? When I move the house to its new location it will be a pigtail 50 amp to 50 amp and 30 amp to 20 amp. No GFI so will this be ok to reconnect the ground? Is the ground rod connecting the first panel on the pole next the the meter enough and should not create a separate ground for the house? I hope this makes sense to someone and can share. Thank you!
 
  #13  
Old 04-25-19, 09:40 AM
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You should measure the resistance from the neutral and ground terminals of the 30A and 50A inlets to the tiny house. If the neutral and ground are properly isolated then it will show as an open circuit. If not there is a connection between them inside the panel or in the branch circuits that it feeds. The neutral wire for each branch circuit could be removed and the resistance to ground measured to help determine where the unwanted connection is located.
 
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Old 04-25-19, 10:00 AM
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Whew.... This might just went over my head. :-) So I am going to take one meter lead to neutral and one meter lead to ground and measure the voltage? What am I looking for? I do this at the panel inside the tiny house on both neatural and ground that feeds the 30 and 50 amp breaker? I then remove one by one the neutral wire for each internal breaker and test again to see if the voltage changes? If it does then that is what is causing the issue of not connecting the ground to its own source without tripping the GFI? So the idea of using the building ground is flawed and it should be no problem connecting the 30 amp breaker and 50 amp breaker to another ground even though the power being brought in is grounded somewhere else? Just trying to get my brain wrapped around this. Thank you!
 
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Old 04-25-19, 01:25 PM
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When you measure between neutral and ground put the meter on the resistance (Ohms) scale. It should be an open circuit (no connection between neutral and ground) and so the meter should show either a very large value in the Megohms, or the meter may say "OL" which means overload.
Start by making these measurements on the plugs of the "pigtails" you mentioned. If you see a relatively low resistance then go ahead and try to track down where the ground and neutral are connected. One way to do this is to continue to do the same measurement above, but disconnect each branch circuit white wire from the neutral bar one at a time to see if the resistance goes way up. If it does that means the neutral and ground are connected on that particular circuit. In this case to be thorough you should reconnect the other neutral wires and measure again, just in case there is more than one circuit with the neutral to ground connection.
Another way to do the testing is to disconnect all of the branch circuit neutral wires, and measure the resistance from each wire to ground to see if any of them show there is a connection.

Of course, both pigtails should be disconnected from the power source during all these measurements.
 

Last edited by engr3000; 04-25-19 at 01:57 PM.
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Old 04-26-19, 10:36 AM
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ENGR3000 your saved the day, thanks! It was as simple as a ground touching the neutral in a outlet box. My last mystery I hope you can solve. When I had the power to the 30 AMP breaker and the 100 AMP breaker was off, the 50 AMP pigtail was still hot. (Or at least I was shocked when I picked up the pig tail and touched the metal) I though the deadman switch prevented that? The breaker was off. I have them grounded the same but that’s it. This seems very strange to me.
 
  #17  
Old 04-26-19, 11:16 AM
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It is possible to get a shock from a neutral wire -- usually it would be just be a small tingle, but a shock is possible under the right circumstances. Do you think this is what happened?

If you actually got a shock from one of the hots, then something is wired incorrectly in your deadman switch.

Assuming you can recreate the situation, use your multimeter on the volts setting to measure between the part you got shocked on and other exposed metal to quantify the problem.
 
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Old 04-26-19, 02:56 PM
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EJDURRETT, did you wire the 50 amp RV inlet to the 100 amp breaker itself or to a separate pair of lugs? The reason I ask is there are "Main Lug" breaker panels where the Main Lug terminals hook directly to the bus bars and therefore would feed all the branch circuit breakers directly if you connected your 50 amp inlet to them. Such a connection would bypass any breaker intended to "backfeed" power to the panel bus, even when this breaker is in the off position.
Just speculating on possible causes for your getting a shock.
 
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Old 04-27-19, 07:46 AM
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I wired the 50 AMP as the main power coming into the panel. I installed deadman switch for the 30 amp box to a 30 amp breaker to use with a generator during a power loss.
I realize this isn't part of your ongoing issue, but why bother with two separate inlets? If it were me, I would just have a single 50A inlet, and get/make a few adapters for different plug configurations.

Your 50A input is max, so there's no issue if you adapt to an 14-30R (30A 240v), 14-20R (20A 240v), or 5-20R (20A 120v). That will give you multiple connection options, with just a few adapters to make the connection.

(Or adapt to twist-locks if desired)
 
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Old 04-27-19, 10:18 AM
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Thanks all! Yes the 50 Amp RV box is connected to the 100 AMP main lug breaker. The 30 is not on the main lug. It’s down on two slots where all the internal breaker are just under the under the main breaker for the deadman switch. When main 50 amp is enabled the metal switch wont let me turn on the 30 amp breaker and vise versa. I did it this way so the 50 amp would feed the entire house on both poles for 220 while the 30 amp is only 110 and have selected breakers on that side for when power go out. So when the 100 amp main lug was off and the 30 amp breaker was enabled, I did get shocked on the 50 amp pig tail. I guess it could be just neutral as both breaker share a neutral and ground bar? I just want to make sure that was not a back feed situation.
 
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Old 04-27-19, 10:46 AM
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Just for clarification purposes could you provide the make and model number of the breaker panel? Or a picture of the wiring to the 100A and 30A breakers.
I think what you're describing is fine but I just want to make sure.
 
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Old 04-28-19, 04:09 AM
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Old 04-28-19, 08:29 AM
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That is a "Main Breaker" panel not a "Main Lug" panel which is fine. I just wanted to make sure you didn't have a main lug panel because with these it's possible to wire directly to the bus without going through a breaker. So something else was causing you to get a shock. As mentioned you should measure voltages on your 50A pigtail to make sure your safe. It wouldn't hurt to attach a receptacle (with no cable on it ) to the plug on the 50A pigtail. That would further prevent the possibility of any shock and also protect the plug pins from mechanical damage.
 
  #24  
Old 04-28-19, 09:16 AM
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Ok I will do that. I thought my electrical saga was over but unconvered another problem today. I was installing all the plugs today and I have a plug tester. I also was testing Neutral/ground per Engr3000 recommendations. Half of the houses plugs shows it correct on the meter. The other half show hot/neutral reversed. So half the home wants neutral on brass side or larger plug side and other half wants neutral on smaller side or aluminum side. What in the world is the reason for this? Is it ok?
 
  #25  
Old 04-28-19, 09:25 AM
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They are receptacles not plugs. Test using a multimeter. Things like receptacle tester can be fooled.
 
  #26  
Old 04-29-19, 05:29 AM
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Hot/ground reverse indication is often actually an open or bad ground.
 
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Old 04-29-19, 04:37 PM
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I assume that you have 120V powering the tiny house whether you do it through the pigtail for the 30A, or the one for the 50A RV inlet? I'm also assuming that you're powering one 120V phase in the panel with through the 30A inlet and the other 120V phase through the 50A one? Unless you have still another 30A pigtail for the other 120V phase.

Your posts suggest the possibility that the hot and neutral might be reversed at the plug or the receptacle on the ends of the 30A "pigtail" cord, or at the 30A RV inlet itself. If so that might explain why you got a shock on the 50A plug because in this case the neutral could be hot even with the main breaker off. Also the outlet tester would show reversed hot and neutral for all the circuits on that phase (which is half of the circuits in the panel).
You should measure the voltage on the neutral bar relative to the ground bar with all configurations that you're using for supplying power to make sure the neutral bar(s) are never "hot".

By the way, on 120V receptacles the wider slot is neutral and the narrower slot is hot. Also the silver colored terminals are neutral and the brass colored terminals are hot.



 
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