# Generators for Dummies



## WMA (Sep 30, 2009)

A customer wants to buy a portable generator for the occasional New England winter week-long power outage. There are loads in the 200-amp main panelboard, as well as in two sub-panels, one of which is in a detached office/garage, that will need to be fed. The house is high-end, and they run their business out of this office.

The customer does not want a pad-mounted generator or an automatic transfer switch, because they don't feel the odds of losing power justify the cost. A portable generator would have to be wheeled out of the garage and parked near the house, maybe 60' and a snowbank or two away. She claims to be OK with the idea of managing loads. Meanwhile, she and her husband are in their 60's, and not mechanically inclined.

Couple of questions:

I'm going to price out a permanent, automatic system for them, anyway, and try to gently make the argument. If they insist on portable, I assume they'll need as big a generator as they can heft. Although I've installed my share of Gentran sub-panels and inlets, I've never been called upon to recommend a particular generator, until now. What's the most powerful portable that can be schlepped around by mere mortals?

Since the loads to be served are spread around in these three panels, I would install a transfer switch at the main. Has anyone used those Interlockkit kits? I've seen them, and poked around the website. I see they're not actually UL listed, which gives me pause. Naturally, I'd call the AHJ. But, I'm wondering what people's experience with them has been.

Are there alternatives that accomplish the same thing?

If the generator stays near the garage, and I make them a honking extension cord to feed the house, how do I size the cord? 60-70' from the generator in, but do you account for the distance of the feeders from the panel back out, say to the garage?

Thanks for ideas...


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## BryanMD (Dec 31, 2007)

WMA said:


> A customer wants
> 
> The customer does not want
> 
> ...


you know what needs to be done.


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## B4T (Feb 10, 2009)

You will get (8) hours of run time for every (5) gallons of gas. 

This is a basic estimate.. size of load and KW of generator are unknown.

Even gas stations can't operate if the POCO is down... so they will be sitting in the dark when the gas runs out. :no:

ATS is the best way to go and a good system increases the value of the house when it comes time to sell.

Portable generators never get "exercised" and chances are it won't start when needed.

A stationary mounted generator "exercises" itself once a week. :thumbsup:


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## B4T (Feb 10, 2009)

BryanMD said:


> you know what needs to be done.


Great song :thumbsup: and it fits the OP :laughing:


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## WMA (Sep 30, 2009)

Yeah, I know what needs to be done, but I can't carry a tune.


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## Power Tech (Aug 23, 2009)

The transfer switches have a isolation contactor that will not allow mixing of power.

I have had the same situation. 

I installed a 120VAC On delay to control a 12VDC wall wart that is plugged into the generator feed. When the generator comes on a delay starts. When it times out it energizes the isolation contactor. 

Put a #6 cord with enough to get to the generator. Bent 3/4" EMT into a hook to hang the cord. 

Poured a pad and built a dog house with chicken wire on the exhaust side for the generator, 10KW. Installed a hinged roof and door. 

Got the check.


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## Missouri Bound (Aug 30, 2009)

Tech...have you done a temperature check on that set up? We (unsuccesfully) built a 6' X 6' X 6' shed for a 4500 watt generator, and in minutes the temp along the solid walls got up over 200 degrees, witht the exhaust pointing out an open wall.


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## Power Tech (Aug 23, 2009)

Missouri Bound said:


> Tech...have you done a temperature check on that set up? We (unsuccesfully) built a 6' X 6' X 6' shed for a 4500 watt generator, and in minutes the temp along the solid walls got up over 200 degrees, witht the exhaust pointing out an open wall.


That is funny, I just got through putting in 2, 4' x 4' fans for 2 generators.

A company built a garage over them and enclosed the heat. 

The reason for putting the fans; One of the generators burned up ($15,000).

The job I was referring to was a small generator, outside, with one side open. Air flow, not an issue.

My advice; When the generator comes on (thermostat) the exhaust fans come on.

I had 2 generators so I had to isolate with contactors.


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## Johnpaul (Oct 2, 2008)

Suggest installing a tri-fuel generator. They can run on natural gas and propane and in many areas where there is natural gas it continues to flow and provides an unlimited source of fuel for the generator. No fuel to age or pumps to replace or tanks to refill (gas is about 8lbs. per gallon so your clients would have to truck around 45 lb. gas cans to keep the fuel tank full and deal with the fire hazard. Even diesel requires additives to keep the fuel in condition. 

A permanent installation of a natural gas feed generator is not going to get legs like a very portable unit and this is also a consideration for something that is going to be used outdoors for a number of days.


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## Johnpaul (Oct 2, 2008)

Northern sells a 6,000 Watt electric start tri-fuel generator for only $2000 and a 10,000 Watt version for $3000. Unless I could hook a generator up to a customer's existing natural gas service or propane tank I would try to talk them out of a backup generator. 

For a gas powered portable I would want to break out key circuits (for furnace motor, fridge, lighting) and try to power just the critical stuff and not the whole house. 

Pity the people who bought into having an "all-electric" home.


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## WMA (Sep 30, 2009)

I will try to talk them out of the portable.
Problem with breaking out critical loads is that they're strewn about the property in three different panels in two different buildings.
Was thinking of a main breaker interlock kit to deal with this.
Thanks.


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## nitro71 (Sep 17, 2009)

I'm not up on generators but I've heard in WA(might be WAC(local) code, not sure) that your generator has to be capable of carrying the full connected load. So no manual load shedding in WA from what I understand. I heard that Siemens? makes a panel that will automaticaly shed loads and meets the requirements. Something for you to check up on? 

Give the customer what they want as long as it meets NEC and you're getting paid. You told them what you thought. Personally I think they over estimate their capabilities to keep their gen set opperating and tote it out in the middle of a bad winter and get it connected and shed the correct loads. NMP(not my problem) though.


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## DSmitts34 (Nov 23, 2009)

*Portable Generator For A Big House*

I have done lots of portable hook-ups over the years and the biggest complaint that I get is a few years later when the generator will not start. That said, I do like the interlock kit and have never had a problem with an inspector and the kits. I use a sharpie and mark the breakers for them to turn off when they use the generator. Generac makes a 12 kw and I think they still make a 15kw but both of those are far from what I call portable. A good 8kw Honda is quiet, gets pretty good run time on gas and is available with electric start. Hope that helps.

Dan


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## WMA (Sep 30, 2009)

Well, I've laid it all out so the homeowner knows what she's in for. Or, rather what the non-mechanical husband is in for, as she's always away on business. Waiting to hear how he feels about the whole thing.

What's a reasonable test/exercise schedule- monthly? How long should the generator run for this?

Thanks.


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## leland (Dec 28, 2007)

http://www.interlockkit.com/catalog1.htm

I've tried these. I don't like the finished product,tough to operate for some 'non-mechanical types.

Got 1 in my own home,I don't mind it.


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## WMA (Sep 30, 2009)

My only experience with one of these was with a Siemens 200a, vertical-throw main. I didn't install; I was just working in the panel. The weight of the interlock plate on the breaker handle was enough to interrupt power when installing the panel cover. Between that experience and the lack of UL listing, I'm rather leery of them.


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## bobelectric (Feb 24, 2007)

those interlock kits are great for 6 to 12 circuits in residential applications with the wheel out generator.


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## doubleoh7 (Dec 5, 2009)

Maybe they need 2 portable generators. One for the home and one for the office. Trying to feed subpanels can get messy.


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## WMA (Sep 30, 2009)

Their eyes are pinwheeling at the thought of maintaining one. By "messy" do you mean in terms of keeping track of what's on and what's off? Or something else that I'm not considering?


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## doubleoh7 (Dec 5, 2009)

Yeah, i was thinking about them keeping track of what circuits are energized from 3 places if you use a simple interlock. There is not any way to feed individual circuits at the two sub panels if you use a generator panel such as a Gen Tran. It makes my head spin just thinking about how to explain these issues to some customers.:confused1:


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## captkirk (Nov 21, 2007)

A permanet stand by is by far better but you wouldnt feel so bad leaving it all behind if you left the house.


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## adk (Jan 6, 2010)

I maintain a 6, 10, 20 and 30 KW generators and if designed correctly you never have to leave a "perminant unit " behind. The buildings they are in all should be designed so that you can pull one in 15-30 minutes.
The 20 kw that I maintain has over 22,000 hours  on it without a rebuild.


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## nrp3 (Jan 24, 2009)

I only put those interlock kits into customer's homes who I think can manage them. I use the kits made by the manufacturer of the respective panel. Square D has them for both QO and Homeline. I forget whether its GE or Cutler Hammer has a panel cover with it. You can buy the panels with it from gentran. I have the Homeline version in my home and it works good enough.

The fuel additive, exercise, and oil changes are key.


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## frank (Feb 6, 2007)

Why not try to sell them a mini windmill and inverter with battery pack. They run heat free and need no effort to start up. Models for home use start from 6kVA and cost less than a stanby generator system. I have never installed one but have looked over a 12 ft 20Kva one installed by a pal. Most impressed.


Frank


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## adk (Jan 6, 2010)

The payoff perhaps? The lack of available reliable "wind".
Payoff is everything and since these are not affordable their payoff is not worth talking about.

** Definition of affordable** - if the guy down the street quits smoking cigarettes for one year he can buy one with the money he has saved. Anything other than this is not affordable.


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## Amish Electrician (Jan 2, 2010)

You can install a manual transfer switch. This would allow you to directly power up to six circuiits with the portable genny.

You can readily find gennys with wheels on them, or just mount one on a cart.

Connecting the genny to the transfer switch can be done with a PROPER extension cord - no suicide cords here!

"Cheap" gennys typically have poor voltage regulation, and are hard on electronics. They're also noisy. And the guzzle gas. I'd look for a proper Honda or Panasonic for these folks and avoid the auto parts store specials.


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