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Another Generator Question: Generator Tripping When Plugged into Inlet ....

Another Generator Question: Generator Tripping When Plugged into Inlet ....


Old 02-07-14, 01:24 PM
Thread Starter
Join Date: Apr 2008
Posts: 17
Another Generator Question: Generator Tripping When Plugged into Inlet ....

So, I've been looking around and can't seem to find an answer here.

After loosing power for nearly 7 days last February up here in MA, I decided I needed to have a way to feed my generator to my panel now that I moved to a house with a well and boiler that have no other way of powering.

I have a Square D Homeline 30/40 panel, about 8 years old. I decided to attach the generator using a two phase 30A breaker at positions 2 and 4using the Square D brand interlock kit. My generator is a Briggs and Straton 5500 Storm Responder generator bought last year. I have a 35' NEMA 14/30 extension cord (using 10/4 stranded extension cord) to send the power to the Reliance inlet mounted on outside of my house. From the inlet to the panel is about a 35' run of 10/3 Romex, with the hots going to the 30A breaker, and the neutral and ground both on the neutral bar. The panel does not appear to have any independent grounding connections that are not bonded to the neutral. (Unfortunately, the location of my panel didn't allow me to go any shorter on that Romex run. I later added a Reliance Wattage meter next to the Square D panel to ensure I balance the loads, however, this problem was occuring prior to adding the meter.)

Here's my issue. The second I plug the generator into the inlet, the generator's breaker trips. This happens regardless of whether the 30A breaker is on (with the main off) or off. I first thought it was a double bonding issue tripping the GFCI, so I disconnected the ground connection at the inlet to separate the generator and the panel grounds. No dice, the generator still trips the second I attach it to the house at the inlet, despite the 30A breaker still being off.

I also pulled off the inlet cover, detached the 10/3 Romex, and then plugged the inlet into the unconnected inlet plug. No trip. So it would seem whatever issue is present at the panel and that the extension cord is fine.

All connections have been double and triple checked.

Any idea what I'm doing wrong? I use the generator in the yard on occasion, so I'd really prefer not to unbond the ground at the generator if at all possible.

Any help is appreciated.
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Old 02-07-14, 01:56 PM
Join Date: Sep 2013
Posts: 85
Is the neutral bonded to ground in the generator? That would cause the GFCI to trip. There may be a jumper that you can remove, check your manual.

In order to connect with the generator bond connected, you need to use extension cords or switch the neutral. I don't believe switching the neutral is feasible with an interlock setup.

Electricians jump in here, please.
Old 02-07-14, 07:18 PM
Join Date: Mar 2010
Location: USA
Posts: 3,100
Are you sure that the Romex cable from inlet to panel is not bad?

Unhook that cable from the panel breaker and then plug in the generator to see if it works (although with no loads).

Or maybe the position of the breaker spans two fins on the same leg (bad, instant short for a backfeeding generator) as opposed to opposite legs (correct for 240 volts). Leg or phase assignments do not always altenate one for one as you go down the rows of brea

Last edited by AllanJ; 02-07-14 at 08:08 PM.
Old 02-07-14, 09:37 PM
Join Date: Oct 2013
Location: United States
Posts: 235

I first thought it was a double bonding issue tripping the GFCI
I am curious, your generator is being connected with the 30amp 120/240 cord and receptacle and going to a 30/2 breaker in your panel. Where is the GFCI that is tripping and what does it have to do with your generator? There are no GFCI's on that generator or required on the 30Amp circuit. Am I reading something wrong?
The grounds on the generator are bonded to all the grounds on all the receptacles and bonded to the generator neutral (page-9 of your manual). Is the breaker in question tripping from a short?
Old 02-07-14, 11:56 PM
Thread Starter
Join Date: Apr 2008
Posts: 17
Bahtah, I thought the generator had a GFCI to make it OSHA legal at job sites. I was under the impression that bonding the neutral at the generator and having the same ground line also bonded at the panel would cause the ground wire to act as a parallel neutral and this trip the GFCI on the generator. So I disconnected the ground wire at the back of the inlet; the metal inlet box itself is grounded, but it does not connect to the extension cord. I thought this would fix the problem but it did not. So perhaps I have a short then if there's no GFCI.

About the only thing I haven't done is checked to see if the Romex is bad on the unlikely chance somehow the cable got damaged during install. I'm going to take AllenGs advice and disconnect the wires at the panel and see what happens.
Old 02-08-14, 03:03 PM
Join Date: Oct 2013
Location: United States
Posts: 235

Bahtah, I thought the generator had a GFCI to make it OSHA legal at job sites.
Here is what I found in the generator manual. I noticed that this generator cannot be sold in California. Don't know why except I see no GFCI protection on the 120V Duplex Receptacles.
120 Volt AC, 20 Amp, Duplex Receptacles
The duplex receptacles are protected against overload by a
two pole rocker switch circuit breaker.
Use each receptacle to operate 120 Volt AC, single-phase,
60 Hz electrical loads requiring up to 2,400 watts (2.4 kW) at
20 Amps of current. Use cord sets that are rated for 125 Volt
AC loads at 20 Amps (or greater). Inspect cord sets before
each use.
120/240 Volt AC, 30 Amp, Locking Receptacle
Use a NEMA L14-30 plug with this receptacle. Connect a
4-wire cord set rated for 250 Volt AC loads at 30 Amps (or
greater). You can use the same 4-wire cord if you plan to
run a 120 Volt load.
This receptacle powers 120/240 Volt AC, 60 Hz, single phase
loads requiring up to 5,500 watts of power (5.5 kW) at
22.9 Amps for 240 Volts or two independent 120 Volt loads
at 22.9 Amps each. The outlet is protected by a two pole
rocker switch circuit breaker

Generator produces hazardous voltage.
Failure to isolate generator from power utility
can result in death or injury to electric utility
workers due to backfeed of electrical energy.
When using generator for backup power, notify utility company.
Use approved transfer equipment to isolate generator from
electric utility.
Use a ground fault circuit interrupter (GFCI) in any damp or
highly conductive area, such as metal decking or steel work.

DO NOT touch bare wires or receptacles.
DO NOT use generator with electrical cords which are worn,
frayed, bare or otherwise damaged.
DO NOT operate generator in the rain or wet weather.
DO NOT handle generator or electrical cords while standing in
water, while barefoot, or while hands or feet are wet.
DO NOT allow unqualified persons or children to operate or
service generator.
Looks like the manufacture is telling you to provide your own GFCI when needed. I think I agree with AllenJ, somewhere there is a short.
Old 02-08-14, 07:54 PM
Join Date: Sep 2009
Location: USA
Posts: 488
Looking up the generator I don't see ANY GFCI on any connection. Do you see any "test" buttons or anything that indicates you have a GFCI on the generator?

You have a short. A neutral/ground bond won't trip a breaker.

Alan is on the money here to check the cable and the breaker.

Can you post pics of the wiring to the inlet and in the panel?

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