Transfer switch question

[electrified_cc]

Hello. I hope someone can help me out. Here in Eastern CT, we been seeing something. Little background on us. We are a larger Generac residential / industrial dealer. We do complete turnkey projects. Our company name is AC/DC Industrial Electric. Here is my issue. We been seeing home owners and less then par to installers, installing Generac pre package home standby generators with 200 amp SE rated automatic transfer switches on 100 amp services. The inspectors have been passing them and when I call them to the plate they tell me don’t worry about it! I am trying to find the actual article or articles in the 2020 NEC. I know it’s probably in article 230 Servcies or article 240 over current protection, but I am not sure exactly where it spell this out. A good friend of mine is an electrical engineer inspector for n a town we do work in and I asked him. He down right says no it cannot be done. But a lot of other “building “ inspectors are approving it. I would like to show these inspectors why they are wrong in approving these installations and try to make them understand. Not throw them under the bus, but try to teach them. I hope everyone understands what I am trying to do. Thank you in advance to everyone. I also am hoping maybe Mike Holy can weigh in on this. Again. Thank you….

 

[augie47]

I think the "devil is in the details"... are they changing the conductors on the service side of your ATS or just supplying the 200 amp ATS with existing 100 amp service conductors ?
(The load side gets a little tricky due to tap rules and grounding rules)

 

[don_resqcapt19]

If there is still downstream protection at 100 amps and the generator cannot supply more than 100 amps, I would not have an issue with it, but it would not be code compliant. I would not have an issue because the service OCPD only provides overload protection and if all of the connected loads are on the load side of the 100 amp breaker in the panel, the service conductors are still protected from overload at 100 amps.

 

[Amps]

Can you post the Genrac specs of the transfer switch?

 

[hillbilly1]

2020 nec would allow it as an emergency disconnect, since the emergency disconnect is not required to have ocp. The problem may be though, it doesn’t disconnect the generator too.

 

[electrofelon]

Hello. I hope someone can help me out. Here in Eastern CT, we been seeing something. Little background on us. We are a larger Generac residential / industrial dealer. We do complete turnkey projects. Our company name is AC/DC Industrial Electric. Here is my issue. We been seeing home owners and less then par to installers, installing Generac pre package home standby generators with 200 amp SE rated automatic transfer switches on 100 amp services. The inspectors have been passing them and when I call them to the plate they tell me don’t worry about it! I am trying to find the actual article or articles in the 2020 NEC. I know it’s probably in article 230 Servcies or article 240 over current protection, but I am not sure exactly where it spell this out. A good friend of mine is an electrical engineer inspector for n a town we do work in and I asked him. He down right says no it cannot be done. But a lot of other “building “ inspectors are approving it. I would like to show these inspectors why they are wrong in approving these installations and try to make them understand. Not throw them under the bus, but try to teach them. I hope everyone understands what I am trying to do. Thank you in advance to everyone. I also am hoping maybe Mike Holy can weigh in on this. Again. Thank you….

Since no one has said it, 230.90(A) would be the section prohibiting this, unless it can be considered the emergency disconnect as hillbilly mentioned.

 

[Hv&Lv]

Gonna see if I have this right..
the generator has a 100 amp breaker (or less depending on size), the service size is 100 amp in the house.
They are adding a 200A ATS. Are they using 4/0 to the panel or smaller?

the only way they could see over 100 amps is on utility service and a fault happens in the transfer switch to the main panel.

 

[electrified_cc]

Since no one has said it, 230.90(A) would be the section prohibiting this, unless it can be considered the emergency disconnect as hillbilly mentioned.

Thank you very much! I know it was in either. Article 230 or 240….. again. Thank you

 

[jap]

installing Generac pre package home standby generators with 200 amp SE rated automatic transfer switches on 100 amp services.

In my mind, there's simply not enough information given here to determine if any code has been violated or not.

JAP>

 

[electrified_cc]

Gonna see if I have this right..
the generator has a 100 amp breaker (or less depending on size), the service size is 100 amp in the house.
They are adding a 200A ATS. Are they using 4/0 to the panel or smaller?

the only way they could see over 100 amps is on utility service and a fault happens in the transfer switch to the main panel.

No. Still #2 aluminum and 100 amp meter socket

 

[electrified_cc]

I think the "devil is in the details"... are they changing the conductors on the service side of your ATS or just supplying the 200 amp ATS with existing 100 amp service conductors ?
(The load side gets a little tricky due to tap rules and grounding rules)

All conductors are staying the same. #2 aluminum. Supplying the 200amp SE rated ATS with 100 amp conductors. (#2 aluminum). In the main panel the 100 amp main breaker remained.

 

[jap]

All conductors are staying the same. #2 aluminum. Supplying the 200amp SE rated ATS with 100 amp conductors. (#2 aluminum). In the main panel the 100 amp main breaker remained.

What is the size of the generator output breaker?

JAP>

 

[Hv&Lv]

No. Still #2 aluminum and 100 amp meter socket

Ok. Makes sense now. Everything is still basically 100 amp service except the generac ATS.
What harm is there? There is now a 200A breaker where there was no breaker at all. The house is still protected at 100 amps at the main, the generator has a 100 amp output breaker feeding the ATS.

Sounds like the inspector is using his head and thinking…

Call it an outside disconnect and let it go.

 

[jap]

Ok. Makes sense now. Everything is still basically 100 amp service except the generac ATS.
What harm is there? There is now a 200A breaker where there was no breaker at all. The house is still protected at 100 amps at the main, the generator has a 100 amp output breaker feeding the ATS.

Sounds like the inspector is using his head and thinking…

Call it an outside disconnect and let it go.

Where in this post was it ever said that the generator had a 100 amp output breaker?

Unless I missed something the size of the output breaker on the Gen set was never indicated.

Therefore, there's still not enough information given to clarify a code violation or not.

JAP>

 

[kwired]

Ok. Makes sense now. Everything is still basically 100 amp service except the generac ATS.
What harm is there? There is now a 200A breaker where there was no breaker at all. The house is still protected at 100 amps at the main, the generator has a 100 amp output breaker feeding the ATS.

Sounds like the inspector is using his head and thinking…

Call it an outside disconnect and let it go.

Those service conductors landing in a single overcurrent device must have 100 amp protection if they are only 100 amp conductors. The "feeder side" of the OCPD however could be lesser ampacity if it complies with tap rules in 240.21.

Service conductors supplying multiple service disconnects can be sized per the calculated load though, but individual taps to individual service disconnects must still be sized per the OCPD they are supplying. Can get more complex with service disconnect supplying say a single motor load though. Reading through all that applies you generally can use same size conductor for the service conductors as you supply the motor branch circuit with in that situation. I've done many 100 HP well motors with 2/0 copper SE conductors and 175 amp time delay fuses for OCPD, which still works out but if motor won't start on that you can increase up to 225 amps, or even have up to 350 amps for circuit breaker applications

 

[Hv&Lv]

Where in this post was it ever said that the generator had a 100 amp output breaker?

Unless I missed something the size of the output breaker on the Gen set was never indicated.

Therefore, there's still not enough information given to clarify a code violation or not.

JAP>

Well, let’s think about this…
A generac 26 kW has a 125A output breaker.
Doesn’t make much sense to put this generator on this house since he said the house had a 100A main.
Now sizing the generator the same as the house breaker would be a 24kW or a 22kW. These come with a 100A output breaker.
Saving some money and getting smaller, a 20kW has a 90A output breaker, and they keep getting smaller from there.

Still, you have a generator output breaker feeding the load. So if it’s a 60A, that could feed a 200A in the house panel..

the generator output will not go through the 200A OCPD on the ATS, so all is well with the generator end. Even if it did, so what..

the utility side coming from the Meterbase to the main in the panel never had any protection at all, and is probably a #2 AL going to the topside of the main breaker.
So we add an ATS for a generator, with a 200A OCPD where there NEVER WAS ONE BEFORE.

Use the #2 from the Meterbase that was going to the main, reroute it to the topside of the 200A in the ATS. Feed #2 out back to the panel main like it has been for many years.

Whats the harm?
Even with the #2 after the 200A in the ATS, it’s still better than it used to be.

And if the ATS happens to be after the main, we’ll then the size of the ATS breaker is a moot point.

In my opinion…

 

[gene6]

Since no one has said it, 230.90(A) would be the section prohibiting this, unless it can be considered the emergency disconnect as hillbilly mentioned.

I agree with this.
And if its using the 2020 NEC emergency disco, where does the grounding / bonding happen?

 

[jap]

Well, let’s think about this…
A generac 26 kW has a 125A output breaker.
Doesn’t make much sense to put this generator on this house since he said the house had a 100A main.
Now sizing the generator the same as the house breaker would be a 24kW or a 22kW. These come with a 100A output breaker.
Saving some money and getting smaller, a 20kW has a 90A output breaker, and they keep getting smaller from there.

Still, you have a generator output breaker feeding the load. So if it’s a 60A, that could feed a 200A in the house panel..

the generator output will not go through the 200A OCPD on the ATS, so all is well with the generator end. Even if it did, so what..

the utility side coming from the Meterbase to the main in the panel never had any protection at all, and is probably a #2 AL going to the topside of the main breaker.
So we add an ATS for a generator, with a 200A OCPD where there NEVER WAS ONE BEFORE.

Use the #2 from the Meterbase that was going to the main, reroute it to the topside of the 200A in the ATS. Feed #2 out back to the panel main like it has been for many years.

Whats the harm?
Even with the #2 after the 200A in the ATS, it’s still better than it used to be.

And if the ATS happens to be after the main, we’ll then the size of the ATS breaker is a moot point.

In my opinion…

You're basing all of this on the assumption of the size of the generator and output breaker.

Which we were never given.

JAP>

 

[Hv&Lv]

You're basing all of this on the assumption of the size of the generator and output breaker.

JAP>

Yeah, but good common sense tells me he isn’t putting a generator in that’s bigger than his main…

 

[xformer]

IMHO, A Switch is a Switch.... A 200 amp Rated switch can switch a load rated up to 200 Amps.