Go Back  DoItYourself.com Community Forums > Electrical, AC & DC. Electronic Equipment and Computers > Electrical - AC & DC
Reload this Page >

Circuit breakers tripping; issue going from 110v to 4-prong locking 125/250v?

Circuit breakers tripping; issue going from 110v to 4-prong locking 125/250v?

Reply

  #1  
Old 02-28-17, 10:15 AM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
Circuit breakers tripping; issue going from 110v to 4-prong locking 125/250v?

Hey folks,

I own a food truck and recently moved to a new house. Months back, I asked an electrician for a solution to connect to shore power in order to run a few appliances overnight. The appliances are connected to a 30 amp circuit panel in the truck. The only electrical connection coming out of the truck was a male 4-prong locking 125/250 connection that plugged into the generator. The electrician made me a short connector with a 4-prong female twist lock on one end and a 3-prong 110v male connection on the other end so that I could just run an extension cord from a standard 3-prong outlet at the house.

This worked great at the old house, but at the new place I've tried several different outlets and the circuit trips each time I connect an extension cord to the truck. Mind you: this happens when all of the breakers are switched off. I've tested these outlets with a medium-load appliance and they held up fine, so I'm a bit worried about my wiring. My electrical knowledge is pretty limited, but I'd love to have a lead to go on so I can figure out how to get this fixed.

Thanks!
 
Sponsored Links
  #2  
Old 02-28-17, 10:39 AM
Member
Join Date: May 2015
Location: USA
Posts: 3,138
Received 1 Vote on 1 Post
Try plugging in just the adapter cord without the truck plugged in to the cord.

Does everything still work ok when you plug the truck into the generator?

I assume you know that no 240 volts loads in the truck (if there are any) will work with the cheater cord....

Do you have a multimeter?

Do you know if the new home outlets either GFCI or AFCI protected? Do the breakers that are tripping have a test button or any indicators?
 
  #3  
Old 02-28-17, 10:48 AM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
Oh, I meant to mention that. The adapter still seems to be working (green indicator light on) up until it gets plugged into the connection on the truck.

Everything works off of the generator, and all appliances are 120v.

The panels here do have a test/reset button and a green indicator light; the ones at the old house did not.

No multimeter, but I do have a basic voltage tester.
 
  #4  
Old 02-28-17, 11:03 AM
Member
Join Date: May 2015
Location: USA
Posts: 3,138
Received 1 Vote on 1 Post
Sounds like you have GFCI protected circuits at the new house. It's possible there is a ground fault in the truck, or perhaps ground and neutral are even bonded in the truck's panel; that will cause the GFCI to trip.

Can you remove the cover of the panel in the truck and take a good pic of the inside of the panel and post it here? (power disconnected of course!)


http://www.doityourself.com/forum/el...-pictures.html

[edit]: and maybe a pic of your adapter and the breaker in the house that is tripping?
 
  #5  
Old 02-28-17, 11:27 AM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
Sure. Pardon the lousy photography. Here's the inside of the box:

Name:  Breaker box.jpg
Views: 330
Size:  33.2 KB

The adapter:

Name:  Adapter.jpg
Views: 250
Size:  20.3 KB

And the outlet:

Name:  Outlet.jpg
Views: 242
Size:  17.9 KB
 
  #6  
Old 02-28-17, 11:34 AM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Location: USA
Posts: 4,181
Received 25 Votes on 24 Posts
The same circuit breaker in the house trips or different breakers? Does that outlet trip?its hard to tell from that pic,are the green conductors connected with the white ones on a terminal strip?
 
  #7  
Old 02-28-17, 11:36 AM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
I've only tried the outside outlets, but all three have tripped.
 
  #8  
Old 02-28-17, 11:43 AM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Location: USA
Posts: 4,181
Received 25 Votes on 24 Posts
How about the green and white conductors in the panel?
 
  #9  
Old 02-28-17, 11:49 AM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
Here's a better angle of that part:

Name:  P_20170228_124551.jpg
Views: 274
Size:  29.2 KB
 
  #10  
Old 02-28-17, 11:49 AM
pugsl's Avatar
Forum Topic Moderator
Join Date: Mar 2008
Location: United States
Posts: 8,604
Received 29 Votes on 27 Posts
Are the 3 outlets you tried on same breaker?
 
  #11  
Old 02-28-17, 11:58 AM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
Sorry, I should clarify this:

Nothing has gotten back to the breaker panel yet. The trips are happening at the actual outlets. There's a switch on the breaker box labeled "outside GFI", but from what I just tested, that only controls one of the outside outlets.

Also, the panel I've included pictures of is the one inside the truck, not the house. Just wanted to clear up any potential confusion there.
 
  #12  
Old 02-28-17, 12:02 PM
Member
Join Date: May 2015
Location: USA
Posts: 3,138
Received 1 Vote on 1 Post
The GFCI is tripping because you have ground and neutral bonded in the truck's panel. That provides a parallel path for neutral current and the GFCI thinks there is a ground fault. Evidently the outlet you used at your old house was not GFCI protected.

So, how to fix?

Separating grounds and neutrals in the panel, and removing the bonding screw will solve the problem with the GFCI tripping, and we can give you instructions on how to do that.

But...what I am not sure of is if it is ok code and safety wise to separate them on a food truck.

Hopefully one of the pro's here with more experience in this area will weigh in....
 
  #13  
Old 02-28-17, 01:34 PM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
Interesting; thanks for the info. I've snooped around some RV forums to look for a solution here and haven't found anything definitive, but this article seemed to lay it out my problem:

Generator bonding and grounding -

I just wanted to see if I understand this: is the issue that the panel in my truck is a sub-panel when connected to shore power, and therefore counts as a second ground/neutral bond in the system?

If so (and this is my understanding of this from various RV threads), would it then be safe to separate them as at the truck as long as I'm connected to a grounded shore power connection, but potentially unsafe depending on how the generator is grounded?

As far as I can tell, my generator (Honda EU7000is) doesn't have a neutral bond. Solutions I've seen range from bonding them at the generator (not recommended by the manufacturer) to using a grounding rod (logistically annoying), and finally a "transfer switch", though I'm not overly familiar with that.

It sounds like bonding them in the generator only causes issues if I use it to power a house or some system other than the truck. Are there any other drawbacks?
 
  #14  
Old 02-28-17, 01:45 PM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,944
Received 42 Votes on 40 Posts
I just wanted to see if I understand this: is the issue that the panel in my truck is a sub-panel when connected to shore power, and therefore counts as a second ground/neutral bond in the system?
That's a correct understanding of the problem.

If so (and this is my understanding of this from various RV threads), would it then be safe to separate them as at the truck as long as I'm connected to a grounded shore power connection, but potentially unsafe depending on how the generator is grounded?
Also correct.

A transfer switch may be a decent option. A reasonable option would be to unbond the food truck subpanel and create two shore power cords -- one bonded in the plug head for use with the generator and one unbonded for use with shore power.

The best option would be to install a 30A 120/240V circuit from the house panel specifically for shore power. You only need a double pole non-GFCI/non-AFCI 30A breaker, some 10-3/g cable and a 14-30 receptacle. In that case it is still technically incorrect for the truck panel to be bonded, but it is much less of a problem with a dedicated shore power circuit.

The mention of earth grounding here is irrelevant to the problem, btw. It's all about the best/correct placement of the ground-neutral bond.
 
  #15  
Old 02-28-17, 01:51 PM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
The best option would be to install a 30A 120/240V circuit from the house panel specifically for shore power.
Unfortunately I don't own the house. I think there also may be some situations where I could plug into a 15-amp connection while out working rather than running the generator, and would likely run into the same problem if they were GFCI protected.

I like the two shore power cords idea, too. I'll run that and the transfer switch by an RV tech and see what he recommends. Thanks for the expertise! I'm a novice to this stuff right now, so it's always nice to have it explained well.
 
  #16  
Old 02-28-17, 05:27 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,673
Received 519 Votes on 489 Posts
You could do it with the one 4 conductor main/generator cord. Two hots, neutral and ground to a 4 prong plug for the generator. You would be balancing the 120v loads across the 240v generator.

Then you could use an adapter cord that would go from 4 conductor(female) to 3 conductor standard male cap. The hots would be combined into one. The neutral and the ground.

This would require the grounds and neutrals to be separated at the breaker panel which is the way it was supposed to have been from the start.
 
  #17  
Old 03-06-17, 02:15 PM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
I pulled the ground wire out from the screw and capped it off and now I'm able to hook up to the home outlets without tripping them. I'm working on a ground/neutral bonding plug for the generator, but in the mean time, how do I go about wiring the ground back into the panel? Do I need to add another bus bar and move all of the ground wires over to it?
 
  #18  
Old 03-06-17, 02:44 PM
Member
Join Date: May 2015
Location: USA
Posts: 3,138
Received 1 Vote on 1 Post
Yes, you would add a ground buss bar (there are mounting holes on the side opposite the neutral buss), move all the grounds to it, and then remove the green bonding screw from the top of the neutral bus.

If you purchase a ground buss bar made for your brand of panel it should line up with the predrilled/tapped holes.
 
  #19  
Old 03-07-17, 12:26 PM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
Looks like wherever I move this, a few of my ground wires are going to come up short. I suppose I need to splice a few inches of extension onto the existing wires? What's the recommended way to do that?
 
  #20  
Old 03-07-17, 12:38 PM
Member
Join Date: May 2015
Location: USA
Posts: 3,138
Received 1 Vote on 1 Post
You can use a wire nut to add on extensions as needed. Use the same or heavier wire, either green or bare.
 
  #21  
Old 03-08-17, 02:01 PM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
So, here's the ground buss bar I found.
Name:  bar.jpg
Views: 128
Size:  43.1 KB

It definitely lines up with the holes in the electrical panel. Does the larger incoming ground need to go into a separate larger lug (for instance), though, or was that only necessary when they were bonded?
 

Last edited by PJmax; 03-08-17 at 02:35 PM. Reason: added pic from link
  #22  
Old 03-08-17, 02:33 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,673
Received 519 Votes on 489 Posts
That bar looks good. Every green wire must go to it. It doesn't matter where the larger one is. If you look at the new bar you'll see every other hole is larger. Use one of those.
 
  #23  
Old 03-08-17, 04:10 PM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
OK, here's what I ended up with:

Name:  P_20170308_170211.jpg
Views: 139
Size:  41.9 KB

And a closer look at the new ground bar:

Name:  P_20170308_170222.jpg
Views: 171
Size:  27.2 KB

It's a little tight on that side; hopefully it's not an issue for that black incoming cord insulator to be that close to the ground bar.

Does anything look awry?
 
  #24  
Old 03-08-17, 05:54 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
Blue is only for hot. The blue needs to be changed to green to be code compliant. Other then that minor problem it looks okay.
 
  #25  
Old 03-08-17, 06:15 PM
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
Damn. Hardware store was out of 12 gauge green by the foot. Is the wire any different, or is that purely for identification?
 
  #26  
Old 03-08-17, 08:11 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
Purely for identification.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: