2 150 amp service entrance breaker with Generac 22kw whole house generator

[texie]

if breaker is in panel and i want to run 2 main panel would i just get 2 150 amp service rate panels and tie them in together. There is no load side to put non service rated t switch because breaker is build into panel. is this correct thinking

This changes everything. I thought you had 2 150 amp enclosed main breakers and the load centers were separate and could put the ATS in between. So you have 2 MB load centers connected directly to the meter can?
Edit to add: I see that this is the case a shown in your post #3.

 

[Fred B]

if breaker is in panel and i want to run 2 main panel would i just get 2 150 amp service rate panels and tie them in together.

Are you referring to a service rated ATS? Or are you adding a service panel? Tie together?

There is no load side to put non service rated t switch because breaker is build into panel. is this correct thinking

? The load side of the NS ATS is the house panels that are now with addition of the ATS and a main breaker a sub panel with seperated N/G.

Now back to where you started. Is this a single service or 2 separate services? (Not talking just the 2 panels inside)
If there is a single service drop, you have one service, and there should be a disconnect or meter disconnect that seperates the one service to the 2 panels, or is this running feeder taps from meter? If there are 2 service drops that likely an issue itself, if one residence.

It sounds as if there is more to the existing installation that is not included in your OP.

 

[wwhitney]

Generac should have info on setting up two ATSs in a master/slave configuration.

Except we call it leader/follower these days.

Cheers, Wayne

 

[brantmacga]

Generac controls are kinda funky, but shouldn’t be a problem. Load shed may be a problem though, because the load would be split between the two transfer switches, so I don’t know if the Generac software would be able to control load shed with two switches instead of one. You could shed the larger non-critical loads using a relay that is de-energized when on generator power.

Generac Smart Management Modules are purely frequency based, which is why there is a hard limit of 8. You can use more if you set them to full lockout mode, but there are only 8 frequency settings per module. There is no software component to them. If you use any of the load shed relays in the transfer switch, that counts against your limit of 8. If using multiple switches and using the built-in relays, you will need to stagger the loads; as in, if you use relays 1-2 and one switch, you would need to use 3-4 on the other. Also if using relays combined with SMM’s, the SMM priority setting needs to be below the relays. For example, let’s say you use all four relays + four SMM’s. The SMM priority settings will start at #5, and continue to #8.


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[hillbilly1]

Generac Smart Management Modules are purely frequency based, which is why there is a hard limit of 8. You can use more if you set them to full lockout mode, but there are only 8 frequency settings per module. There is no software component to them. If you use any of the load shed relays in the transfer switch, that counts against your limit of 8. If using multiple switches and using the built-in relays, you will need to stagger the loads; as in, if you use relays 1-2 and one switch, you would need to use 3-4 on the other. Also if using relays combined with SMM’s, the SMM priority setting needs to be below the relays. For example, let’s say you use all four relays + four SMM’s. The SMM priority settings will start at #5, and continue to #8.


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So there is no amp settings that trigger the load settings? If there is, that is software.

 

[Dennis Alwon]

I would contact generac and make sure the use of 2 transfer switches would work. Then install 2- 200 amp service rated transfer switches (since you didn't buy 150 amp ones) but you will have to change the conductors from the meter to the panel with 200 amp capacity.

 

[brantmacga]

So there is no amp settings that trigger the load settings? If there is, that is software.

No. The SMM’s and transfer switch relays are measuring frequency output to know when to drop out. They’ll drop under utility power as well if the frequency drops below the set threshold. They do not know the difference between the two sources. Under power loss they all disconnect, and return to closed as long as the frequency holds at 60hz.


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[wwhitney]

No. The SMM’s and transfer switch relays are measuring frequency output to know when to drop out.

So the 8 settings you mentioned correspond to something like 59.95 Hz, 59.90 Hz, 59.85 Hz, etc, or some other spacing?

Cheers, Wayne

 

[brantmacga]

I would contact generac and make sure the use of 2 transfer switches would work. Then install 2- 200 amp service rated transfer switches (since you didn't buy 150 amp ones) but you will have to change the conductors from the meter to the panel with 200 amp capacity.

Two recent installs; The generator does not know how many transfer switches or load management modules are connected. There is no communication between any of the equipment other than signaling to transfer.

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[brantmacga]

So the 8 settings you mentioned correspond to something like 59.95 Hz, 59.90 Hz, 59.85 Hz, etc, or some other spacing?

Cheers, Wayne

Yes


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[hillbilly1]

No. The SMM’s and transfer switch relays are measuring frequency output to know when to drop out. They’ll drop under utility power as well if the frequency drops below the set threshold. They do not know the difference between the two sources. Under power loss they all disconnect, and return to closed as long as the frequency holds at 60hz.


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I figured they would use current sensors, but oh! I forgot this is Generac! LOL!

 

[wwhitney]

Yes

So if the loads start dropping out when the generator gets overloaded and the frequency falls, is there anything that keeps a perpetual cycle from happening? Even with say a 30 minute wait before the load comes back online, for a multi hour outage it would seem like a bad idea to keep trying to restart a load every 30 minutes.

Cheers, Wayne

 

[brantmacga]

So if the loads start dropping out when the generator gets overloaded and the frequency falls, is there anything that keeps a perpetual cycle from happening? Even with say a 30 minute wait before the load comes back online, for a multi hour outage it would seem like a bad idea to keep trying to restart a load every 30 minutes.

Cheers, Wayne

No. But I don’t think current monitoring would solve that either.

If you as the installer identify a load that would likely overload the generator every time, you should set that to full lockout mode.


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[wwhitney]

If you as the installer identify a load that would likely overload the generator every time, you should set that to full lockout mode.

Sorry if my questions are basic, but my inference from your comment on "full lockout mode" is this: the grid is reliably at 60.0 Hz, and the generator never operates at 60.0 Hz. Say instead it operates at 59.9 Hz, and call that step 0. Full lockout mode would be a load shed module set at step 0, it never runs on generator. If the generator starts to get overloaded, it drops the frequency further to initiate the step 1, step 2, etc load shed devices as required. Not sure then if the 8 settings referred to earlier count step 0 or not.

Is that correct?

Thanks,
Wayne

 

[brantmacga]

Sorry if my questions are basic, but my inference from your comment on "full lockout mode" is this: the grid is reliably at 60.0 Hz, and the generator never operates at 60.0 Hz. Say instead it operates at 59.9 Hz, and call that step 0. Full lockout mode would be a load shed module set at step 0, it never runs on generator. If the generator starts to get overloaded, it drops the frequency further to initiate the step 1, step 2, etc load shed devices as required. Not sure then if the 8 settings referred to earlier count step 0 or not.

Is that correct?

Thanks,
Wayne

yep, you've got it.


Here's a link to the SMM spec sheet that explains it some....

https://www.generac.com/GeneracCorporate/media/Library/content/all-products/generators/home-generators/guardian-series/20kVA/10000029407-Rev-E.pdf

 

[jeramiepluemer]

Are you referring to a service rated ATS? Or are you adding a service panel? Tie together?

? The load side of the NS ATS is the house panels that are now with addition of the ATS and a main breaker a sub panel with seperated N/G.

Now back to where you started. Is this a single service or 2 separate services? (Not talking just the 2 panels inside)
If there is a single service drop, you have one service, and there should be a disconnect or meter disconnect that seperates the one service to the 2 panels, or is this running feeder taps from meter? If there are 2 service drops that likely an issue itself, if one residence.

It sounds as if there is more to the existing installation that is not included in your OP.

There is no breaker outside. I have to have utilities come and open pedestal. I am sure they split in there. Remember I am a rookie but learning.