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Onan Generators

To transfer or not to transfer.


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  #1  
Old 01-28-2014, 02:53:29 PM
Jack D D Jack D D is offline
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Default To transfer or not to transfer.

For the past several months, I've been pondering the different ways to legally connect my 6.5 NH to the house wiring during power outages. Until that is solved, we are back feeding through a 240V outlet that I added for that purpose. We own a duplex in the country with a tenant on the other side. We are on well water, so when power is out we also are without water. Our home is also all electric. Electric heat, electric water heater, electric range, etc. You get the idea.

First, I looked at manual transfer switches, but the prices and limitations made them unsuitable for our needs. During short outages, the manual transfer switch probably could be passable, but we have 6-240V circuits that we could need during long outages.

Then I looked at the Generlink transfer switch. This seemed like a very good option....except that my meter base is some 50' from where the generator will be and the cord would have to run through my tenants garage to reach the meter base. Not a real good solution, but that would give me access to all of my house circuits by playing musical breakers. I called our power company to inquire about Generlink and they had not heard of it. They like the idea of the Generlink and are investigating it and could offer it to customers in the future.

I then looked at panel interlocks. This seemed like a good option, but wasn't sure if they were a legitimate option. Are they approved? Do they need to be approved? My answers to those questions seem to be no and no. From all I've been able to ascertain, they only need to meet the requirements of the code and no lab testing and approval is needed. At least that's the way I see it. The panel interlock will give me full access to all of the circuits in my panel....just not all at the same time. I also ordered two digital volt/ampere meters for my generator, but I think I'll mount those near my distribution panel so I can see the generator output and load where all the switches are.

There are two that are made to fit my T&B panel and one is almost twice the price of the other. I couldn't find any reviews detrimental to either, so I went with the lesser pricey one. It should be here today or tomorrow, then the fun begins. Rearranging the circuits in the panel to make room for the generator input breaker will be a challenge. A couple of half heights will be added because my panel is full now and I need space for a 240V 30A breaker. I'll also need to open the wall up to gain access to the panel box and studs to bore holes for wire passage to the attic. I anticipate a few bruises along te way. Crawling in attics at my age is no walk in the park. I can't afford to hire it done. I'm a DIYer whenever possible.
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Old 01-28-2014, 03:13:15 PM
len k len k is offline
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Default Re: To transfer or not to transfer.

I believe as per code, One of the requirements for interlock use is you need to be able to remove the neutral/ground bond at the gen. Because with a interlock that bond usually is at your main breaker panel, and you don't remove it. (It's the one N/G bond issue.)

Also for inspection some cities/towns don't allow them, like NJ.

In the past there was some discusion here that code may only allow interlocks on SUB panels not main panels, but I think the current viewpoint is they are allowed on main panels. It's not obvious why they would be a problem on main panel. Comments???

When moving breakers watch out for branch circuits with shared neutrals, their hots need to be on opposite buss bar hots, put them on same hot and neutral wire amps don't canel and wire can smoke.

As far as testing, I think code basically says everything has to be listed , I think this just means have a UL lable. (which means UL tested it and it does what it claims)

Last edited by len k; 01-28-2014 at 03:39:30 PM. Reason: add paragraphs
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Old 01-28-2014, 03:46:33 PM
Jack D D Jack D D is offline
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Default Re: To transfer or not to transfer.

When we first moved here (16 years ago) we had a 60A(?) panel and I, personally, changed it to a 200A panel. I had the power company confirm that the incoming lines were of proper size (they were) and inquired about inspections. They weren't interested in inspections. Just said to let them know when I wanted it re-connected. There won't be any inspections.

As far as bonding goes, I've learned that unless I have GFCI protection on my genset (I don't), bonding at the genset (it is) is really not likely to be a problem. Using the interlock is really no different than backfeeding (it justs makes it safe), which I have been doing and will do until I get the interlock installed, It works and I see no reason that it will not continue to work. Again, there will be no inspection. I haven't determined if I will, but the genset is only a few feet from the house ground rod and could actually ground the genset to that rod if desired. And that might be desireable. Just not sure.

I'm old and I'm cranky. I spent my working life as a building contractor and it sticks in my craw that I need to get permission from the county, and pay to get it, to do anything to my own property. I understand the need for some things, but it has gone way too far, IMO. If things continue this way, it won't be long before we are all assigned our own personal rubber rooms, so we don't get hurt by our own stupidity. I can remember many times when I had to tell the inspectors what the code says...because they had it all wrong. Sorry for the rant, but permits and inspectors are a thorn and some of those that I have had dealing with seem to forget they work for us not the other way around.
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Old 01-28-2014, 03:48:07 PM
Dave Edmonds Dave Edmonds is offline
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Smile Re: To transfer or not to transfer.

Since you have potential loads WELL in excess of your generator's capacity, make sure you have proper protection at the generator end, just in case too many loads get turned on at once. The 30-amp breaker in the panel (being fed backwards; don't think it cares which way the power flows) will provide some protection, but some breakers will carry a fair amount in excess of their rating for some time, before they trip. Don't want to let the magic smoke out of the generator! With no more generator than you have, as compared to the loads you're feeding, you will definitely be doing quite a bit of load switching during a typical day.

Since you do have so many electrical loads that you depend on, you might do some long-term casual shopping for a larger generator (like 15-20 KW or so), so you wouldn't have to do so much load-shifting. If you're not in a hurry, some good bargains do show up every now and then. I personally recommend that anything you get is painted GREEN!

Dave Edmonds
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Old 01-28-2014, 04:01:57 PM
Jack D D Jack D D is offline
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Default Re: To transfer or not to transfer.

The generator is well protected by the two 30A push button breakers that Onan put on it and the two 20A 120V and one 30A 240V breakers that I added, along with the 30A input at the main panel. Lots of breakers. As I mentioned, I'm also putting two digital Volt/Amp meters near the panel so I can see what's happening as I turn on/off different circuits. I have three 6.5NH's all setup with wheels and outlets. Maybe I could trade all of them for a larger genset. But then, a larger genset will burn a lot more fuel. If it weren't so expensive and difficult, I'd consider paralleling two gensets.
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Old 01-28-2014, 04:06:47 PM
len k len k is offline
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Default Re: To transfer or not to transfer.

Sounds like the push button breakers may be thermal types, that's good. To protect the gen windings you want to use a thermal breaker, not house type.

Onan uses Airpax thermal ones on the 6.5NHE, 7NHM and JB?? gens. The house type breakers don't trip soon enough to keep the winding magic smoke in. You can connect house type breakers downstream of the thermal breaker if you want to protect smaller wire branch circuits coming off the thrmal breaker
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Old 01-28-2014, 04:11:57 PM
Jack D D Jack D D is offline
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Default Re: To transfer or not to transfer.

Quote:
Originally Posted by len k View Post
Sounds like the push button breakers may be thermal types, that's good. To protect the gen windings you want to use a thermal breaker, not house type.

Onan uses Airpax thermal ones on the 6.5NHE, 7NHM and JB?? gens. The house type breakers don't trip soon enough to keep the winding magic smoke in.
I assume that's the case. They are push to reset and can't be manually opened. A 30A on each hot side of the output.
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Old 01-28-2014, 04:45:12 PM
Ted_Cool Ted_Cool is offline
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Default Re: To transfer or not to transfer.

I've been planning to use motor overload relays to protect my sets - I think they're a better match to the nature of a generator.

The class 10 trip curve looks suitable.

I like a few - the Schneider group of companies make several nice ones.

Square D class 9065 Motor Logic ss210 look pretty good for the money.

Good Luck!
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Old 01-28-2014, 05:58:07 PM
len k len k is offline
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Default Re: To transfer or not to transfer.

I've been planning to use motor overload relays to protect my sets

I'm not very familar with them , but from what I read once they seem similar to thermal breakers. They have various "heaters" you can install to change the trip point to match windings rate of heatup. Problem is I know nothing about matching it. And they are pricier than thermal breakers. By using a Airpax breaker you can "ride the coat tails" of the Onan engineers who already matched the breakers to the gen.

I've noticed Onan seems to use Airpax thermal breakers on their gens JB or JC, NHD, NHE, NHM and ones newer than NHM . When I look up the model numbers on ebay the breakers for these all seem to have the same basic rating: Must trip amps are 125% of rated amps, delay is ~63 (saw 64 once), and the look of the breaker are always the same. I think they are all the same type breaker.

Last edited by len k; 01-28-2014 at 07:10:49 PM. Reason: typo
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Old 01-28-2014, 07:20:28 PM
Ed Sparks Ed Sparks is offline
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Default Re: To transfer or not to transfer.

quote"For the past several months, I've been pondering the different ways to legally connect my 6.5 NH to the house wiring during power outages. Until that is solved, we are back feeding through a 240V outlet that I added for that purpose. We own a duplex in the country with a tenant on the other side. We are on well water, so when power is out we also are without water. Our home is also all electric. Electric heat, electric water heater, electric range, etc. You get the idea.

First, I looked at manual transfer switches, but the prices and limitations made them unsuitable for our needs. During short outages, the manual transfer switch probably could be passable, but we have 6-240V circuits that we could need end quote.

Thats where you run into legal issues as you have a duplex rental property.
Your insurance company would frown strongly any shortcut to backfeeding .

You know that one 6.5 will not power much of your required load being all electric.
Does your 200 amp panel feed both sides of the duplex?
If you had separate services , then you could feed each side separately, & split the load between two gensets.
Electric resistance heat is a heavy use load for gensets.
same with stoves or water heaters.

You will have to be very actively involved with load management to avoid letting the magic smoke out. Turn on the well pump till tank is filled then shut it off & turn on some of the electric heat units for a while & repeat over & over again.
Forget the stoves , dryers or water heaters unless nothing else is on, & even then limited use.

From your description of load, I would expect you need an absolute minimum of 15 kw and probably closer to 25 kw even up to 35 kw for fairly normal use in mid winter.
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