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Apollo67 01-27-2012 03:42 PM

Generator connection Ė Question - Final Plan
I think I have my final plan laid out but before I start anything I have a few questions I thought Iíd run by the boards for input.
The house is 2 yo new construction with no modifications yet so everything is current and to code.
After 2 storms of 3 days each without power here in central MA I thought Iíd prepare for the next big one.
I bought a 6500 W generator (8000 peak) and plan to switch off my whole panel so I donít have to be selective in what rooms get power. (most are on their own breakers)
To do that I ordered an OE Cutler Hammer interlock cover to replace the existing cover and will back feed the generator in positions 2/4.
Although rated to 8000 peak watts the outlet on the generator is 240v 30A so wiring the feed to the house for anything more than 30A seemed pointless.
I didnít quite need one that big but the generator was a great price and gives me a little higher running wattage.
Since it was the limit of the generator outlet the plan was to use a 30A breaker for the back feed and use 10-3 w/ ground to run to my connection point.
Thatís when the questions started cropping up.

Question 1: 10-3 or 8-3?
The run is about 80 feet to the other end of the house where I want to have the generator connection.
Based on that I thought I might need to switch to 8-3 but several people, some of them electricians, told me thatís unnecessary and 10-3 is perfectly fine.
I checked out a few online calculators and I was getting conflicting information so I went and looked at some installations at friendsí houses and theyíre all wired with 10-3 so I settled on 10-3.
Then I saw a thread earlier today about a similar subject and now Iím not sure what to think again.
That thread was and suggested the total length to use when figuring voltage drop is from the generator to the farthest eligible receptacle from the panel which in my case doubles the length.
Does voltage drop really come into play for a normal emergency generator application?
Most everything that I look at from TVís to coffeemakers have a range of acceptable voltages anyways so it seems like it wouldnít and thatís why people keep saying 10-3 is fine.

Question 2: Conduit or no?
The run for the feed wire will go through an unfinished basement for about 60í and the other 20í or so go through a finished garage area before going out through the wall.
Does the portion of the feed wire in the finished garage need to be in conduit and if yes what size/type?

Question 3: Anchor or no?
I originally planned to use the C/H anchor kit on the back feed breaker but again was told it was not needed.
Does a back feed breaker need an anchor kit or as seen on the Interlockit website to be zip tied to the adjacent breakers in 1/3?
For those that caught that, I was headed the direction of an Interlockit kit until I found out I could get the real C/H interlock cover for the same money and not have to retrofit my panel.

Question 4: Grounding at the generator?
The generator has a screw on the motor and in the manual itís noted to connect to a suitable ground using 8 ga wire.
Since the generator will be grounded to the house ground via the 10-3 this additional ground seems like it wound create a ground loop and should be avoided in my situation.
Iím sure there are reasons for it when itís not being connected to a house like this but since it is should I ignore it?

Other observations on anything I may have missed or the plan in general would be helpful.
Iím not a total noobie to electrical but I want to make sure this is done right.


Bluehawks 01-27-2012 04:08 PM

Put in a ground rod close to where the generator is located and run a wire from the ground rod to the generator, Their is a spot on the frame to hook the wire to. I put a clamp on one end of the wire and a fork on the other end. Keep the wire with the generator when not in use and use the ground every time you use the generator. It is for your protection.
You should shut off the generator when refueling too. Sure you can get by without doing it, but that one time you are toast.

The rest of your questions, I'm not sure what your talking about for sure, I kind of got lost at HI and then I got focused again later. Too much reading for me.

Last week I couldn't spell ellectrision, this week I are one.:no:

Good luck,

rrolleston 01-27-2012 05:00 PM

2. Anytime wires are not inside the wall I like them in conduit.

3. I like to have any breaker feeding the panel anchored

dmxtothemax 01-27-2012 05:34 PM

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 !

rrolleston 01-27-2012 05:40 PM


Originally Posted by dmxtothemax (Post 836357)
Then 10 gauge is rated for up to 55 amps,

10 gauge is only rated for 30 amps. Long runs maybe good to step up one gauge or two.

jbfan 01-27-2012 06:00 PM


Originally Posted by rrolleston (Post 836361)
10 gauge is only rated for 30 amps. Long runs maybe good to step up one gauge or two.

Depending on the type of wire, 10 gage is rated for more than 30 amps.
In most cases, code only allows 10 to be installed on a 30 amp breaker.

Apollo67 01-28-2012 08:33 AM

Thanks for the answers so far but I was hoping for more code specific ones.
As in does NEC code call for conduit when passing through finished spaces and if so what type. I've run plenty of wires in walls and unfinished space and have some experience with conduit. I just didn't know if it was required or optional.
And does NEC call for breaker anchoring or is it also optional?
I know 10 awg is able to take more than 30a but code calls for it on 30 amp branch circuits. This is probably why I found conflicting info and was looking for clarification on the voltage drop issue.
The last issue isn't so much code specific but maybe it is. I know a ground is needed for protection BUT I am concerned that since the genny will be grounded via being directly connected to the house ground that grounding it again where it is running is going to create a ground loop which can cause problems of it's own.

jbfan 01-28-2012 09:22 AM

Run the wire through the joist.
Unless your area requires conduit, the code does not.

Apollo67 01-28-2012 09:47 AM

maybe you missed it. the garage is finished so I have no access to the joists or studs. It must be part of the local building code to board and finish the garage interior since I doubt the builder would do it otherwise.

biggles 01-28-2012 10:03 AM

main thing with running a generator is just keep things normal during a black out with the house powered up.your total amps will be minimum 65 amps heating,lights sump pumps are the main draws on starts,with the rest of the house pretty consistant.tops 15 amps running on each side of the CB panel breakers good test is take a normal night read the amps on the panel as is heat running frig running sump if you have it....normal lights PCs TVs get an idea of what the generator will's not that much and nowhere near 65 AMPS.depending on your heating system running it with a generator if it has electronic control board might need a closer look at might just sit with generated "dirty voltage"

Apollo67 01-28-2012 10:20 AM

Got a lot of stuff to keep status quo or risk losing stuff again. Fridge, freezer, kegerator :thumbsup:. Then of course we want lighting and heat and maybe even entertainment.
BUT more important than all of those things, we need water (private well).
That one is 2400w by itself. It's is a 3 ph variable freq constant pressure drive so it is on almost anytime the water is on. Granted not at the full 2400 watt but it doesn't have any way to tell what it's drawing as it applies or reduces power to the motor.
I calced out my runtime loads and starting requirements and added that 2400 to it and a 5K was a little short if most of them were running at the same time and something else tried to start.
I know in real world it's probably not going to happen but you never know so I decided to go bigger to make sure I never ran into a limit. Another was power stability. Research indicated the larger ones produced more stable cleaner power. The last was a great deal on it at Home Depot.
I just wanted to check on some install questions before I started pulling any wires for my hookup. I'd like to get it connected and do a dry run with it to make sure it does what I need it to before I get into an emergency situation and find out the hard way.

Stubbie 01-28-2012 11:10 AM

What generator manufacturer ? Some will not be friendly with entertainment systems without line conditioning.

I like conduit but UF-b direct buried would work. You need to get enough voltage to the well motor/pump. How far is that wire wise from the generator? And do you know the wire size in the branch circuit after the circuit breaker?

You will need two voltage drop calculations based on the expected or estimated total load on the generator and wire size to the panel and then the branch circuit length to the well pump...etc The general rule is to stay at or below 5% for total of both. Here is a link to calculators that will let you play with several VD calculations ..

Bluehawks 01-28-2012 11:41 AM

I will tackle the grounding question again, hopefully I can do a better job of explaining it.
The ground that I mentioned before has to do with the frame of the generator, not the ground that you are running with the wires from the plug.
Their is a grounding attachment point on the frame of the generator, you want to put a fork on the end of a #10 wire and hook it up to that, than put a spring clamp on the other end of the wire and hook it to the ground rod. If you would rather use a ground rod lug for this end that is fine.

This ground is to protect you from getting shocked or electrocuted if you touch the frame.

Man that is long winded,

Apollo67 01-28-2012 11:58 AM

Stubbie, It's a Rigid RD6800 with the Yamaha motor if it helps. It's supposed to be pretty clean but manufacturers hardly ever give you all the info you want. It's one of many reasons I want to be hooked up while we do have line power so I can do a dry run and do some testing when it's not an emergency.
Offhand I don't know the total length to the well pump but I presume since the 240 v at the panel from the poco drives it normally then as long as I have 240 at the panel from the genny it shouldn't be an issue. Plus the Subdrive 3 ph converter gets in the mix so really the 240 v only needs to get from the panel to that which is about 5 feet.

Bluehawks, sorry, I should have mentioned this in my op. The genny has a neutral bonded frame and since the connection to the house carries both a neutral and a ground and the ground goes to house ground I was concerned about creating a ground loop.

biggles 01-28-2012 05:17 PM

what you will do is get a routine when the power drops out what to do first then last before the switch's easy.tip always check the oil and question is how much gas to big it the tank on the genny?i went 12hrs on a 4 gallon thru Irene doing a shutdown 6AM then at 6PM threw a neighbor a 115V cord for his FIOS/Verizon module...warning:no:never ever try to fill a generator when its running or just was shut off hot from a 5 gallon container..figure out someway to pour the gas into a fixed funnel or(bottom off a plastic container) out of 1 gallon containers like those windshield washer gallon containers i find are good.might consider couple of emergency lights mounted (hall,living room,kitchen) to paint the ceiling so you have 90 minutes of lighting and one over the generator won't hurt.. where's the generator going to be when not in use...shed...garage??reread that well water draw 2400watts might consider a #8-3 pull last ting when you lose power before a genny strat up stut all your refrigerators off...lite the house up and restart them it's a PITA but if you bounce power on a startup the refer will cycle and cycle itself into history....same procedure when the pole comes back

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