What did I do wrong with this generator install?

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Old 10-23-16, 11:50 AM
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What did I do wrong with this generator install?

Hello all, first post in a home improvement forum. I'm new to this stuff so be easy on me. This house and shed were built in 2006. I bought it 95% complete. The shed had a 3 wire bundle loose inside so I traced it back to the panel. It was also loose in the panel so I figured the previous owner ran short on change, did not finish the job.

Here's the arrangement. Shed not too far from main panel, in the garage. I want to connect a generator to the panel, from the shed, using an interlock in the panel. Some last minute reading tells me that I should ground the generator frame to earth to avoid a shock hazard, so I have done that.

I bought a 240V breaker that matches my panel just fine. It has 3 terminals with a neutral pig tail, that I have wired to one of the common rails. Everything is rated for 20 AMPS (5,000 W generator).



This is essentially how it's wired:



The panel and you'll see the breaker in the top left spot. I KNOW, I KNOW, NO INTERLOCK YET. This will be moved down near the main switch when I have the time and have confirmed my wiring to work as intended.








This is where I have grounded the generator wiring and also where the breaker neutral wire terminates:


Some other pictures:















So the result? After waiting for my wife and child to leave the house, I began the first test. I powered both the main panel and sub panel off. I then switched all individual breakers to the off positions. I started up the generator and plugged it into the plug in the shed. Leaving the MAIN PANEL OFF, I turned the 240V breaker ON. Everything OK at this point.

I held my breath and then turned on a single 120V breaker for 2 unloaded outlets in my garage. This is where things go south. I hear a buzzing in the panel for about 3 seconds then a small pop from the 240V generator breaker. I immediately turn the 240V breaker OFF and unplug the generator.

OK, so I let the smoke out of the breaker. After assessing inside the panel for any damage and not finding any, leaving the generator disconnected, I reapplied street power to the panel and tested the GFCI button on the generator breaker. It no longer shuts the breaker off like it did right after installing it. Apparently my first test blew out this circuit inside the breaker. Doh! There goes $100.

So where did I go wrong? Should of just called an electrician, I know. But I actually did call the original guy who wired the whole house. He's busy busy, yadda yadda. Hence, why I figured I'd give a shot at this project myself.

Clearly, there is a grounding problem, but which wire is it? Thanks for the help.
 
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Old 10-23-16, 11:56 AM
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Why didn't you just use a regular 2pole 30A breaker ?
 
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Old 10-23-16, 12:08 PM
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I did buy one from HD as it was like $16 but it doesn't fit my panel....and well, ahem, there are times, I, uh, want to power my shed so since it's an external structure, I decided to be fake-sake and got the GFCI breaker.
 
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Old 10-23-16, 12:11 PM
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Locate the correct two pole breaker. Powering from your shed is no reason to use a GFI breaker at panel. The GFI breaker at your panel will be source of grief.
 
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Old 10-23-16, 12:14 PM
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Some last minute reading tells me that I should ground the generator frame to earth to avoid a shock hazard, so I have done that.
Only if it is not connected to another system already grounded. In your case you don't ground the generator frame to earth.
I KNOW, I KNOW, NO INTERLOCK YET. This will be moved down near the main switch when I have the time and have confirmed my wiring to work as intended.
That should be done before any testing. Did you at least turn off the main breaker.

Really not sure what you did or why you used a GFCI breaker.
  • The generator must be outside.
  • There must be an inlet (male) not a receptacle that the generator plugs into.
  • There must be 8-3 UF-b cable buried at least 24" running to a 40 amp non GFCI breaker in the main panel only.
  • For safety the breaker must have a hold down clip.
  • At the main panel the red and black go to the breaker.
  • The white and bare to the neutral bar.
 
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Old 10-23-16, 12:26 PM
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So where did I go wrong? Should of just called an electrician,
Yes your over your head here IMO..

1. You cant have two bonds. Grounding the generator is the wrong thing to do. You need to know if your gen has a floating neutral or not. Onee gen is tied to the panel its bonded there, and you may have to lift bond at gen side.

2. The neutrals and grounds in your panel should be separated. Its a code requirement here in NJ when we hook a gen to the panels ..

3. What size wire is run from the shed to the panel? Is it even sized correctly?

4. You may need a neutral switching transfer switch if you cant locate the bond in your gen, if you have one..

So many things wrong with what your doing.. Bad things can happen if your unsure..

Say you energize an appliance in your home and electrocute a family member!! How would you feel?

Your best bet if the wire is sized big enough is to install a 10 circuit transfer switch next to your panel. Pull the shed whip out of the main and run it in the transfer switch. Then pick 10 emergency circuits.. ( Its emergency power... Not a day at the Hilton)

https://www.amazon.com/Reliance-Cont...ransfer+switch
 
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Old 10-23-16, 01:00 PM
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The neutrals and grounds in your panel should be separated. Its a code requirement here in NJ when we hook a gen to the panels ..
That's only if you install a main rated transfer switch as the main panel now becomes a subpanel.
 
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Old 10-23-16, 01:03 PM
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Red face

As luck would have it, this is my second time writing this reply as the first time we lost power for 1 second. Heavy rain and winds this weekend....

Good to know about not needing the extra grounding. I thought that was suspect but didn't want to start a fire in the shed.

I certainly did turn off the main breaker before applying generator power. And if it ever came down to someone else using this, such as when I rent or sell the house, the plug will be removed. I would never let someone use a non-compliant connection.

I've been using 120V in the shed for a while now, which is why I was hoping the GFCI would work. There are times when I'm heating my riding snowblower with a 400W light and magnet heater. Typically the snow evaporates off of the blower before I ever give it any heat but I didn't want to start a fire by letting water drip on my appliances out there.

Thanks for the help guys.
 
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Old 10-23-16, 02:10 PM
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The 240V breaker being fed by the generator should not be GFCI simply because it's being backfed which is in reverse of it's designed function.. If the 120V breaker is powering the shed it can be GFCI if needed. And yes... there goes a $100.
 
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Old 10-23-16, 02:17 PM
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The neutrals and grounds in your panel should be separated. Its a code requirement here in NJ when we hook a gen to the panels ..
That's only if you install a main rated transfer switch as the main panel now becomes a subpanel.
Yes I stand corrected... Im thinking whole house gens with power swaps to ATS
 
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Old 10-23-16, 03:00 PM
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You can not safely use the power to the shed cable for the generator. Have you run a new three conductor cable for the generator? Looking at your pictures it doesn't seem to be what you did.

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Old 10-23-16, 05:45 PM
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You can not safely use the power to the shed cable for the generator. Have you run a new three conductor cable for the generator? Looking at your pictures it doesn't seem to be what you did.
BUSTED! Yes, I did take 120V from the generator cable. Unfortunately, the previous owner was also the GC for this construction. He told me that he ran out of money during the build. So all i have going to this shed is 240V and no generator OR a generator and no lights! In addition to crappy finish carpentry, piss poor grass and a pissed off wife, I have a 1/2 wired shed! WTF, mate.

Yes, I suppose that I can just accept that I have 240V to the shed and run a separate 3 wire conductor into the garage to connect a generator. But I'm cheap and finishing this place is running MY budget dry every month.

So I moved to Maine a couple years before the ice storm of '98. We didn't have power for 8 days. But that was up in the woods. Still, though. I'm having another child next year and don't want to risk having no power for a single day.
 
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Old 10-23-16, 05:57 PM
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Your best bet is to set the generator near the house and put an inlet near by.
So all i have going to this shed is 240V
That may be a problem. If your diagram is correct and you have only a black, white, and ground (2-conductor cable) to the shed. You can not use it for 120v. To be used for 120 volts it would have to have a black, white, red and ground (3-conductor cable). The breaker can not exceed 20 amps and depending on wire size may have to be 15 amps.
 
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Old 10-23-16, 06:33 PM
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yes ray... I would not assist this poster untill all info is given. He was asked what wire size etc... We dont know what inlet he has and what not...

Treading in a dangerous are here..

Seems the OP may want to do what he wants and it dont matter what we say here...

Im borderline closing this thread...
 
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Old 10-23-16, 07:45 PM
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I agree, Mike!

LooseNut as I previously wrote: Your best bet is to set the generator near the house and put an inlet near by.

But what do you want to power. You can power at most two 20 amp 120 volt circuits or one 20 amp 240 volt circuit. Is your stove gas? Is your heat gas/oil? Is your water heater gas/oil? If you answer is "no they are electric" to any of the questions then the generator is too small. No sense even trying to use it except for just extension cords to a few lights, the refrigerator, and a TV.
 
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Old 10-23-16, 08:10 PM
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Once you configure the existing cable to the shed to be fed (using a male receptacle) by your generator at the shed, that cable is no longer eligible to receive utility power up at the house panel. The interlock will (and must) keep that (back fed) breaker off when the main breaker for utility power is switched on. You can still fire up the generator (still at the shed) to power the shed while the back fed breaker at the house panel is off.

Later, you may have two cables going between the shed and the house, one with just the generator inlet at the shed and connected to a breaker in the house panel for backfeeding the latter. This is the cable ineligible to receive utility power even if it still has a regular receptacle daisy chained on it. The other cable runs from a non-interlocked breaker at the house panel to feed regular receptacles and lights in the shed. For normal generator usage, current goes from the generator up one cable and down the other to power items in the shed.
 
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Old 10-23-16, 08:52 PM
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You can not safely use the power to the shed cable for the generator. Have you run a new three conductor cable for the generator? Looking at your pictures it doesn't seem to be what you did.
It's 30 amp, 3 conductor + ground, run from the panel to the shed by a master electrician. There is white, black, red + ground.

I agree that the best thing to do at this point is use the 4 wire cable that is pre-installed to supply 240V to the shed and scrap the generator at that location.

Perhaps I will move the 20 AMP male plug to the outside of the house and run a separate dedicated 4 wire cable from there to the panel and properly use an interlock. That would be safest..............................
 
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Old 10-23-16, 09:16 PM
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If you use the cable to the shed for240 volts you can not use it for 120 volts. If you have no need for 340 volts it can be re-purposed as a 120 volt multiwire feed but there are some things you must do to do that.
Perhaps I will move the 20 AMP male plug to the outside of the house and run a separate dedicated 4 wire cable from there to the panel and properly use an interlock.
You haven't answered my questions about expected loads.
Is your stove gas? Is your heat gas/oil? Is your water heater gas/oil? If you answer is "no they are electric" to any of the questions then the generator is too small.
Till you do we can't say if it would make sense to set up for that generator.
 
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Old 10-23-16, 10:00 PM
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If you use the cable to the shed for240 volts you can not use it for 120 volts.
Cant he put a box like I got to my shed.? I have two 20 amp breakers in this panel...

Square D Homeline 50 Amp 2-Space 4-Circuit Spa Panel Main Lug Load Center-HOME250SPA - The Home Depot
 
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Old 10-23-16, 10:06 PM
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Cant he put a box like I got to my shed
Yes, Mike that is correct but I was trying to keep it simple for him. No need for a subpanel if he only wants 120 volts.

It may be time to close this thread and he can start one on the generator and one on the shed.
 
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Old 10-24-16, 06:11 AM
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The existing 10 gauge 3 conductor plus ground cable can be reconnected to the shed wiring with no inlet and no ability and no permissability to feed the generator power up from there.

No panel or breaker is needed in the shed provided that the breaker at the house panel for this line is 20 amps or less. A master switch (also double pole for 240 volts) down at the shed is needed.
 
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Old 10-24-16, 07:37 AM
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Hi guys,

Yup, I was intending on using the existing 3+1 cabling to serve multiple purposes. Y'all have scared me straight. It would not be good to share a bottle of wine with my wife and then have the power go out, only to stumble around in the dark trying to remember what order to do things.

If I were to remember to turn the main OFF before applying generator power (and also turn the gen OFF before turning the main ON), I would also have to remember what breakers could be used with a 20 AMP genny. The most important would be the oil furnace for heat and hot water, pump for the well, refrigerator and some lights. We only lose power for up to a half day when it does happen but no sense in burning the house down just to have some power for a few hours.

If I do stay in this house I'm going to do it right. I'll probably put an air compressor in the shed and run a compressed air line to the garage. That will require some digging so I'll run the electric as required and also get a bigger generator. This 5000W gen was bought while living at our previous house, which was half the size and had a properly installed Gen Tran transfer panel.

I want to sell this place next year so trying not to invest where I won't see a return. My experience with car projects has taught me that when I do things cheap and quick, it costs me more in the long run. I gotta start remembering that. I'll remove the generator plug from the shed and just revert back to a 20 amp, 120V GFCI breaker to supply the shed. Thanks for the advice, guys. Happy Monday.

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Old 10-24-16, 08:35 AM
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pump for the well
If I recall correctly we have had members post having trouble running a well pump on a 5000 watt generator. What is the voltage and full load amps of your well pump?
 
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