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Old 01-28-2012, 07:33 PM   #16
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Generator connection Question - Final Plan


Hey Apollo,

Not an electrician here. Same boat as you, though. Have a well to power, a fridge and TWO freezers, as well as a boiler and now pellet stove.
Like someone else said, pound a ground rod near where you think you'll have the generator and attach it (via cable of course) to the gen.
My cable ran from the breaker box through a finished room. I did not enclose it in conduit, I simply used cable straps and secured it up near the corner of the ceiling. Not sure if that was code or not, but someone for the PoCo came by to inspect and bless, and they didn't say anything (may not mean much). I may some day cover it with molding.

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Old 01-29-2012, 12:17 AM   #17
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Generator connection Question - Final Plan


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Originally Posted by dmxtothemax View Post
If 10/3 refers to 10 gauge awg,
Then 10 gauge is rated for up to 55 amps,
considering your max load of 30a and the long run,
Then 10 gauge is perfect !
You do not need anything bigger !
10 awg copper has never been rated for 55 amps I think your reading the ampacity for 8 awg but even it is not rated for 55 amps unless you have terminations that are rated 90C which is never in residential settings.
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Old 01-29-2012, 02:23 AM   #18
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Generator connection Question - Final Plan


I went back and checked the table of wire size,
it said 55a peak,
A swl would be probably half that say 25a continuse.
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Old 01-29-2012, 10:24 AM   #19
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Generator connection Question - Final Plan


I keep forgetting where your from, it's probably the wire chart your looking at vs what we use here in the USA. We use table 310.16 NEC for just about everything residential except services to homes which is 310.15(b)6 Both charts can be found here..

http://www.jhlarson.com/ind_tables/ind_table.htm
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Old 01-29-2012, 11:00 AM   #20
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Generator connection Question - Final Plan


Thanks guys. I'll probably install the ground rod unless someone tells me different about the ground loop question and the breaker anchor too since thats easy. I was more curious if it was needed.

The genny has an 8 gallon tank and I probably wont run overnight so refueling in the the daylight hours should work fine. It is after all for emergency only.
The refrigerated stuff will last overnight no problem so the only reason I would run late night is heat and I could do that for short periods.
I plan to run it at the driveway end of the house so I'll have light from my truck available anyways. It'll be easier to get from storage to where I want to run it and closer to where I keep fuel and tools for oil changes and stuff. But as seems to always be the case the panel is clear across the other end of the house so I have to run quite a ways to get to it.

Does anyone know for sure if romex in finished areas (the garage space) needs to be in conduit in MA per NEC code?
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Old 01-29-2012, 04:05 PM   #21
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Generator connection Question - Final Plan


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Originally Posted by Apollo67 View Post
Thanks guys. I'll probably install the ground rod unless someone tells me different about the ground loop question and the breaker anchor too since thats easy. I was more curious if it was needed.

The genny has an 8 gallon tank and I probably wont run overnight so refueling in the the daylight hours should work fine. It is after all for emergency only.
The refrigerated stuff will last overnight no problem so the only reason I would run late night is heat and I could do that for short periods.
I plan to run it at the driveway end of the house so I'll have light from my truck available anyways. It'll be easier to get from storage to where I want to run it and closer to where I keep fuel and tools for oil changes and stuff. But as seems to always be the case the panel is clear across the other end of the house so I have to run quite a ways to get to it.

Does anyone know for sure if romex in finished areas (the garage space) needs to be in conduit in MA per NEC code?
The NEC is so complicated on the requirements for earth grounding of portable generators you will be lucky to get the same answer form one electrician to another.

Some of the problem is most of these type generators are neutral ground bonded. Meaning the ground pins of the receptacles are bonded with the frame and neutral of the generator. This is because these generators are generally used to power cord and plug equipment on job sites or to power water pumps etc... Since the generator operates independently as a power source and not connected to any other electrical system (source) it is considered what the NEC calls a separately derived system and must have neutral and ground bonded so that there is an effective fault path over the equipment ground back to the source center tap of the generator windings.
This protects you from a phase fault to the equipment metal frame of the tool your using and trips the generator circuit breaker.

The problem with earth grounding portable generators centers around this separately derived system and non-separately derived system concept.

If your generator has neutral and ground bonded then you must use a transfer switch that will disconnect the utility neutral and goes over to the generator neutral. In this case you drive a ground rod at the generator.

If your not using a transfer switch that switches neutral and you remain connected to the utilitiy neutral and generator neutral your not separately derived and no ground rod is required at the generator.....but then there is another problem .... because both the homes electrical system is neutral ground bonded and the generator is neutral ground bonded you have established a parallel path that circulates neutral current on the equipment ground which can be very dangerous when touching metal parts. If you drive a ground rod at the generator in this situation you could become a link for current to use to get to earth or vice versa.

You fix this problem by calling the manufacturer and asking how to disconnect the bond between neutral and ground. Once you do that then the earthing grounding takes place at the homes grounding electrode system and you would not put a ground rod at the generator.

When you go back using the genny to operate cord and plug power tools and not the home you would reinstall the bonding to put the generator back to a separately derived system configuration. You do not have to install a ground rod because the nec allows a portable generator frame in contact with the earth to serve as the grounding electrode if it is operating only cord and plug tools or equipment.

So in your case and you do not remove the neutral to ground bond you would not install a ground rod because you are not operating under separately derived rules and your solidly connected to the utility neutral making your generator non-separately derived. Your problem will be neutral current using the equipment ground because of the bonding at both the homes service and the generator.

IMO the NEC is not clear how one is to handle an install like yours. So flip a coin. My personal opinion is to forget the ground rod see if there is a way to easily remove the neutral to ground bond of the generator and let the home premise wiring and its grounding electrode system serve as the earth grounding. And for piece of mind I'd wear insulating gloves when touching the generator....
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Old 01-29-2012, 04:26 PM   #22
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Generator connection Question - Final Plan


you MUST disconnect all wires going backwards to meter.
You can kill a lineman feeding anything back into the grid.
The neutral is bonded to the frame, and you need to bond the frame to ground.

To protect yourself from shock hook up the ground rod.

To protect lineman while working to fix the power lines, disconnect all wires going back to meter.

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Old 01-29-2012, 05:46 PM   #23
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Generator connection Question - Final Plan


Quote:
Originally Posted by Bluehawks View Post
you MUST disconnect all wires going backwards to meter.
You can kill a lineman feeding anything back into the grid.
The neutral is bonded to the frame, and you need to bond the frame to ground.

To protect yourself from shock hook up the ground rod.

To protect lineman while working to fix the power lines, disconnect all wires going back to meter.
I'm curious....why is it that most generator transfer switches are 2 pole and do not switch the neutral? How can you backfeed on one wire. Is that possible?
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Old 01-30-2012, 07:47 PM   #24
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Generator connection Question - Final Plan


Thanks Stubbie. The longer description has helped me understand better.
I will avoid the ground rod at the generator since it would create a new parallel path for neutral via the earth since it's bonded at the panel as well. I'll just let the house ground handle the grounding of the generator by it's normal connection. This is what I suspected would be the case in this application but wanted to bounce it around first to get some better educated input.

Now I just have to check local code regarding conduit in finished spaces.
I suspect they will require it to protect the wire from possible damage but I will need to find out what size and type.

Zappa, I'm with you. It never made sense to me how that was possible since neutral's sole purpose was a return path to the source for any imbalance of the poles. With the only source being either line or genny then the return path only goes one place, not both. Plus if it were a safety issue it would be mandatory under NEC which would preclude any sort of backfeed breaker or interlock kit, both of which are code but only switch off the hots. I can certainly understand the requirement for a mechanical interlock to prevent human error in switching them over but from everything I read the only time you need to switch off neutral is if your genny is GFCI all around in which case the neutral bond at the panel appears to the GFCI outlet(s) on the genny as a ground fault and pops the breaker continuously. The one I have is GFCI on the 120 outlets but not on the 240 which is another of the reasons I bought this model. I may at some point use the genny for some other portable power purpose but I haven't thought of any yet and this thing is a bit of overkill for tailgating.

Rick

Last edited by Apollo67; 01-30-2012 at 08:11 PM.
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Old 01-30-2012, 08:44 PM   #25
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Generator connection Question - Final Plan


Quote:
Originally Posted by Bluehawks View Post
you MUST disconnect all wires going backwards to meter.
You can kill a lineman feeding anything back into the grid.
The neutral is bonded to the frame, and you need to bond the frame to ground.

To protect yourself from shock hook up the ground rod.

To protect lineman while working to fix the power lines, disconnect all wires going back to meter.
ATS do not switch the neutral...at least mine does not.

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