Whole House Generator

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Richterfan

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Danbury,Ct
In Connecticut we still use the 2005 code. My question is if its considered an optional standby generator, do you have to carry the full load of the house or is it up to the homeowner to use wisely the wattage installed.
 
The customer decides what size generator he/she wants. You can pick and choose circuits or do the whole house.
 
It's best to install a sub panel they would supply the critical loads and us the Genset to supply that panel that way there is not opportunity to overload the generator.
When you use the genset that is not large enough to supply power to an entire panel and leave it up to the discretion of the homeowner as to what loads they will want to supply what are the chances that they will attempt to supply more loads than originally planned?
 
Richterfan said:
In Connecticut we still use the 2005 code. My question is if its considered an optional standby generator, do you have to carry the full load of the house or is it up to the homeowner to use wisely the wattage installed.
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I'm not aware of any code requirement that makes you carry the whole house load. Jack Homeowner is free to pay for as much or as little as he wants. You just use a manual or automatic transfer switch (which would probably be a bit pricey) and a load center and connect those loads you really want to keep running. IIRC Generac and others will sell you a package that includes the generator, load center, and transfer switch.

A partial list of candidate loads might include: refrigerator; freezer; gas furnace fan and ignition; the circuit for the gas range top/oven since most nowadays are "spark start" instead of a standing pilot; likewise the ignition to the gas water heater; well pump; a central lighting circuit (especially for the basement if that's where the load center is); and maybe a circuit serving a computer and/or entertainment center. Things you want to stay away from to keep costs down: air conditioning; electric heat (except maybe one largish room that can be sealed off from the rest of the house as a "refuge"); electric hot water; electric tankless water heater; electric oven; electric range; and your shop compressor (hey, someone's gotta make a sacrifice!).

Every customer is going to be different. Maybe one's got medical equipment that has to stay up and running. Someone else might have $20,000 worth of tropical fish in a 100 gallon tank; need to keep the filter and heater going. This may be an opportunity to offer value-added service to the customer by really listening to his needs. You can't overestimate the value of being able to run the X-Box while your neighbor is freezing in the dark :D!
 
Richterfan said:
In Connecticut we still use the 2005 code. My question is if its considered an optional standby generator, do you have to carry the full load of the house or is it up to the homeowner to use wisely the wattage installed.
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If you are still under the 2005 code you can hook a 5 Kw up to full panel. It is when you go under the 2008 code that load calc. and the sizing of the generator is adequate for the load if you use an ATS
 
Yes it's while using an ATS. I know what should be done but that's not the question. My question is can you use a 20kw gen with an ATS under the 2005 code to power a 200amp residential service. Inspector is making me do a load calculation but I feel it's not required under the 2005. Again we all know what should be done but is it allowed under this code. The ATS has a 200 amp service rated disconnect in it, if it draws more then it should what's the worse that can happen it will trip the gen breaker.
 
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Richterfan said:
Yes it's while using an ATS. I know what should be done but that's not the question. My question is can you use a 20kw gen with an ATS under the 2005 code to power a 200amp residential service. Inspector is making me do a load calculation but I feel it's not required under the 2005. Again we all know what should be done but is it allowed under this code. The ATS has a 200 amp service rated disconnect in it, if it draws more then it should what's the worse that can happen it will trip the gen breaker.
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Well, if you're lucky it will trip the breaker. If you're unlucky, your load might be large enough cause the generator to go in an undervoltage condition and maybe damage some appliances, unless it has an undervoltage trip.

From the 2005 Edition:

702.5 Capacity and Rating. An optional standby system
shall have adequate capacity and rating for the supply of all
equipment intended to be operated at one time. Optional
standby system equipment shall be suitable for the maxi-
mum available fault current at its terminals. The user of the
optional standby system shall be permitted to select the
load connected to the system.

If you intend to comply with 702.5 and it's for the whole house, how do you know it has adequate capacity without doing a load calculation? In point of fact, even if you're doing only 1 or 2 loads, you still need to do a calc to comply.
 
We are under current code and the way I read it is if you are using an ATS, the generator must be sized for the full load of the house. We usually install a critical load genie panel as well.
 
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