Standby Generator feeding alternate loads

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Theoallen

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Newbury! MA, USA
Hello:

New to this forum and thought I could get some input on a Standby Generator problem.

I have an all electric house and recently sought quotes on a standby generator. I immediately got pushback due to the 20kw resistance heat that is part of my geothermal heating system. I propose reducing it to 10kw but that still didn't excite anyone.
After looking at the problem for awhile I came up with a possible solution. The attached sketch will better describe my idea.
1st I need to isolate the 10kw from the "Main Housel Load Center" (MHLC) and then group together then mandatory circuits that need to fed whether the the "10 kw Resistance Heat"(10kWRH)is on or the MHLC. These would be 2 refrigerators, a freezer and garage door openers. This would be a subpanel fed from the MHLC and the 10KWRH with a manual transfer switch #2 controlling the source.
Starting at the beginning of the circuit there would be a conventional standby generator installation, Utility Power, Generator, and ATS. From the ATS power would go through a 200 amp Safety Switch #1 that would direct the source to the MHLC position "A" or the 10KWRH position "B". in parallel with that switch #2 would be in the same "A" or "B" position which would direct power to the Mandatory Loads based on the source selected by switch #1.

I don't know if here are any smaller alternatives to the 200 amp safety switch it's 37" x 11"x 6". "massive"

I still don't know if the 20kw generator will handle the rest of the house but if not that will just add a conventional generator panel to handle the necessary load items along with the mandatory load items.
The main problem is getting anyone to talk about if. The contractors see that 20kw/100amp breaker in the panel and the law says if you hook up to the panel the generator has to handle the load. I'm hoping this will satisfy the requiremnent.
there doesn't appear to be and potential feedback or dual source issues. The safety switch is supposed to prevent any arc issues during switching.

Thanks

GENERATOR CIRCUIT DIAGRAM A.jpg
 
I am quite confused by the setup you are proposing. Why not just load shed the large loads? Those transfer switches have some nice load shedding capabilities. Also, generac makes a load shed module that senses the generator's imperfect frequency and shuts off a load - super quick and easy to install.
 
I wonder if you back up and tell us what you have now and the problem you want to solve, maybe we can direct you better. I am confused by what you have and what you are adding.

Do you just have a 200A service to a single 200A 120/240V single phase panelboard that services everything and you want to add a 20kW generator to backup whatever it can handle?

In the arrangement you shown now, the two panels fed by Switch#1 will never be able to be on at the same time .... ever .... even during a regular day.
 
I would buy a bigger genset

it can't be much more expensive than what you propose

not sure what code is but iirc you can load shed with a relay disabling the elec ht contactor for example
 
Re: Larger Genset etc.

Re: Larger Genset etc.

The larger genset was mentioned but the contractor said it would be a waste of money given the expected use.
The idea that only one circuit could be on at a time is exactly the intention. My intention is to be able to switch the system to the "B" position which is the bare necessities. This would be when we are away from the house for extended periods. The geothermal system has a few quirks that can shut down the system and there is no auto reset or recovery feature so unless you are there to perform the restart process the heating system is caput until you van manually take care of it.
So with that in mind having the 10kw of electric heat available for these vacation periods along with keeping the refrig, freezer and garage doors operable during a power outage is what I am trying to do.
Now this is all based on what the generator contractors have told me during the quotation process and their observations of my electrical system.
So with us at home the switches in the "A" position the whole house with geothermal heat including the (2)refrig, freezer and garage doors would be running and during a power outage they would keep running. NO(10 kw electric heat)
During extended periods away with the switches in the "B" positions then 10 kw electric heat would be the sole heat source and the (2) refrig, freezer, and garage doors would be powered by the utility or generator in the event of a power failure.
Hence my idea of being able to switch from circuit "A" to "B" which minimizes the impact of the 10 kw electric heat on the total load and the secondary circuit which allows the essential refrig ,freezer etc.
If load shedding will do it I am all for it but I didn't get that feeling from the contractors I have dealt with so far. I got the feeling if it wasn't a straight forward plug and play it was on to the next quote.
 
I have no idea what you are trying to accomplish
waaaay too complicated
just load shed
done every day
iirc you can program loads
eg shut off fridges for an hour and run heat
then swap back
 
Theoallen said:
.....Hence my idea of being able to switch from circuit "A" to "B" which minimizes the impact of the 10 kw electric heat on the total load and the secondary circuit which allows the essential refrig ,freezer etc.
If load shedding will do it I am all for it but I didn't get that feeling from the contractors I have dealt with so far. I got the feeling if it wasn't a straight forward plug and play it was on to the next quote.
Click to expand...

Load shedding will work. Stop over engineering, find a good electrician that knows his stuff, pay him the price he is asking, and don't micro manage him.

How do you find a good electrician you ask? Look for a company or contractor that is not the cheapest, has been in business a good while, and has experience installing generators.
 
Theoallen said:
Hello:

New to this forum and thought I could get some input on a Standby Generator problem.

I have an all electric house and recently sought quotes on a standby generator. I immediately got pushback due to the 20kw resistance heat that is part of my geothermal heating system. I propose reducing it to 10kw but that still didn't excite anyone.
After looking at the problem for awhile I came up with a possible solution. The attached sketch will better describe my idea.
1st I need to isolate the 10kw from the "Main Housel Load Center" (MHLC) and then group together then mandatory circuits that need to fed whether the the "10 kw Resistance Heat"(10kWRH)is on or the MHLC. These would be 2 refrigerators, a freezer and garage door openers. This would be a subpanel fed from the MHLC and the 10KWRH with a manual transfer switch #2 controlling the source.
Starting at the beginning of the circuit there would be a conventional standby generator installation, Utility Power, Generator, and ATS. From the ATS power would go through a 200 amp Safety Switch #1 that would direct the source to the MHLC position "A" or the 10KWRH position "B". in parallel with that switch #2 would be in the same "A" or "B" position which would direct power to the Mandatory Loads based on the source selected by switch #1.

I don't know if here are any smaller alternatives to the 200 amp safety switch it's 37" x 11"x 6". "massive"

I still don't know if the 20kw generator will handle the rest of the house but if not that will just add a conventional generator panel to handle the necessary load items along with the mandatory load items.
The main problem is getting anyone to talk about if. The contractors see that 20kw/100amp breaker in the panel and the law says if you hook up to the panel the generator has to handle the load. I'm hoping this will satisfy the requiremnent.
there doesn't appear to be and potential feedback or dual source issues. The safety switch is supposed to prevent any arc issues during switching.

Thanks

View attachment 19548
Click to expand...

Interest idea and it looks like it would work. But it would be expensive this way.

Generacs new Smart Management Module (SSM) would be an easier approach...

https://www.youtube.com/watch?v=HH2orx8-I6I

Talk to experienced installers in your area up there like the "Generator Connection" or "Powers"...
 
shortcircuit2 said:
Interest idea and it looks like it would work. But it would be expensive this way.

Generacs new Smart Management Module (SSM) would be an easier approach...

https://www.youtube.com/watch?v=HH2orx8-I6I

Talk to experienced installers in your area up there like the "Generator Connection" or "Powers"...
Click to expand...


The Generator Connection was my 1st stop. I went to them and after hearing about the 20 kw heat they decided they would send their experienced electrician down to give me the quote. Well they cancelled once then rescheduled and told me the electrician wouldn't be coming and that their regular estimator would be coming. I questioned that but they assured me he would be capable of getting the correct info to get an accurate quote. The guy that came never mentioned the load shedding, I think I mentioned it but he didn't offer any input. He just told they couldn't deal with the 20kw heat circuit unless they got a massive generator even though I told him that it would be reduced to 10kw. After leaving he called back the next day and told me (verbally, no written quote) they would be able to give me a generator with a limited amount of circuits ($9k), which he said would not include the 20kw heat. I reiterated the 20kw would be reduced to 10 kw he said ok I'll get back to you and that was it. never called again.
Not what I expected.
One written quote $16K no load shedding mentioned, 22kw Cummings generator, no elect heat.
Very frustrating.
 
ActionDave said:
Load shedding will work. Stop over engineering, find a good electrician that knows his stuff, pay him the price he is asking, and don't micro manage him.

How do you find a good electrician you ask? Look for a company or contractor that is not the cheapest, has been in business a good while, and has experience installing generators.
Click to expand...


The Generator Connection was my 1st stop. I went to them and after hearing about the 20 kw heat they decided they would send their experienced electrician down to give me the quote. Well they cancelled once then rescheduled and told me the electrician wouldn't be coming and that their regular estimator would be coming. I questioned that but they assured me he would be capable of getting the correct info to get an accurate quote. The guy that came never mentioned the load shedding, I think I mentioned it but he didn't offer any input. He just told they couldn't deal with the 20kw heat circuit unless they got a massive generator even though I told him that it would be reduced to 10kw. After leaving he called back the next day and told me (verbally, no written quote) they would be able to give me a generator with a limited amount of circuits ($9k), which he said would not include the 20kw heat. I reiterated the 20kw would be reduced to 10 kw he said ok I'll get back to you and that was it. never called again.
Not what I expected.
One written quote $16K no load shedding mentioned, 22kw Cummings generator, no elect heat.
Very frustrating.
 
Theoallen said:
Hi .
Click to expand...
Is your ATS 200 amp and service rated. Can it be mounted in a location that qualifies it as the service disconnect for the dwelling.

An ATS is not equipment that is allowed line side of a service disconnect. You do not need the 200 amp safety switch.

So why not remove switch 1 and switch 2 supply all your loads you indicated supplied by SW 2 to what you are calling the new 200 amp load center

In an outage situation just throw the main in what you are calling the current residential house center

You may want your ATS to be Manuel if your gen is not large enough since you are doing manual load shedding the gen not going to help when your on vacation anyways if its not large enough

other wise you need load shedding to be automatic
 
Theoallen said:
The Generator Connection was my 1st stop. I went to them and after hearing about the 20 kw heat they decided they would send their experienced electrician down to give me the quote. Well they cancelled once then rescheduled and told me the electrician wouldn't be coming and that their regular estimator would be coming. I questioned that but they assured me he would be capable of getting the correct info to get an accurate quote. The guy that came never mentioned the load shedding, I think I mentioned it but he didn't offer any input. He just told they couldn't deal with the 20kw heat circuit unless they got a massive generator even though I told him that it would be reduced to 10kw. After leaving he called back the next day and told me (verbally, no written quote) they would be able to give me a generator with a limited amount of circuits ($9k), which he said would not include the 20kw heat. I reiterated the 20kw would be reduced to 10 kw he said ok I'll get back to you and that was it. never called again.
Not what I expected.
One written quote $16K no load shedding mentioned, 22kw Cummings generator, no elect heat.
Very frustrating.
Click to expand...

The 20KW heat load would be an issue. The 10KW heat load should not be an issue to load manage...IMO

Those geothermal systems seem like a PIA...if you could do it again would you go geothermal again?

Try all Generac certified installers in your area...someone must be competent.
 
online
36-38 kw ng genset with service rated 200 A xfer switch
12-14k

wag install
2 man crew w/truck
3 days
4k
materials $500

pad, shipping figure 2k

total 20k

what you propose using a 15 kw
16k
lot of labor in what you propose
if you can find someone willing to do it

for the difference you get a simpler whole house solution
 
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