Service Disconnect Needed?

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sna1imj

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Location
Bellingham, MA
Occupation
Engineer
Hello,
I have been working on installing my 400 amp service in my house and with the latest storm power outages, we have decided to add a 26KW generator, which comes with 2 200 amp dual transfer switch, I am in MA, and they will not let me connect to the transformer withought firstly passing the inspection; hoevever, the town is requiring me to have a licensed electrician. Him and I were debating whether we need a 400 Service disconnect added or just label my transfer box as such since it is SED rated?
Regards
 
Unless you have some local POCO requirements you should be able to use your two service rated ATS in my opinion.

Outside of the house and grouped together be your best bet.
 
Is this (2) ATS's or a single unit with (2) 200's in it? If latter, then you have an issue with two service disconnects in a single enclosure.

Also I'm not clear on the (2) 200 ATS for a 26KW generator. Seems like with that size generator you should just switch one 200 amp set and keep the other one for non-generator loads 🤔
 
electrofelon said:
Is this (2) ATS's or a single unit with (2) 200's in it? If latter, then you have an issue with two service disconnects in a single enclosure.

Also I'm not clear on the (2) 200 ATS for a 26KW generator. Seems like with that size generator you should just switch one 200 amp set and keep the other one for non-generator loads 🤔
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OP needs to clarify what you said and maybe more. He never mentioned if this is a ATS or a MTS. A double throw 200 amp switch with no OCPD kind of sort of still fits what he described.

He does mention service rated at the end of the post though, so maybe it has at least one overcurrent device in it?
 
electrofelon said:
Is this (2) ATS's or a single unit with (2) 200's in it? If latter, then you have an issue with two service disconnects in a single enclosure.

Also I'm not clear on the (2) 200 ATS for a 26KW generator. Seems like with that size generator you should just switch one 200 amp set and keep the other one for non-generator loads 🤔
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Hello, it is the B&S 71057 Dual Briggs & Stratton 71057 Dual 200A/Split 400A 1ph-120/240V Service Rated Nema 3R Automatic Transfer Switch. we are feeding the house with 400 amp to the meter then with splitting into 2 panels; in addition, I have line side taps with my 52 solar panel system; therefore, i was told a dualy.

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kwired said:
OP needs to clarify what you said and maybe more. He never mentioned if this is a ATS or a MTS. A double throw 200 amp switch with no OCPD kind of sort of still fits what he described.

He does mention service rated at the end of the post though, so maybe it has at least one overcurrent device in it?
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Hello,
It is a single ATS with dual 200 amp breakers for both panels. It will be 2 main breakers in the single ATS and it is SED rated! I was planning on installing it next to my millbank meter socket and label it as such! In MA, this has to be all done by a licensed electrician; but, it seems my electrician is at a loss with the hole thing; because I still need to wire my 18KW PV system on the supply side which would be in the ATS before the main breakers!
Regards

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My POCO has no issues with any of this, it is up to my wiring inspector now, and he is not a very good one! he keeps referring me to retaining a licensed electrician, and my electrician does not have the answers I am looking for yet!
 
Used to be able to get homeowner permits in MA. I don't know whether they cut that out completely or not, but I know most inspectors will not issue homeowner permits.
 
sna1imj said:
Hello, it is the B&S 71057 Dual Briggs & Stratton 71057 Dual 200A/Split 400A 1ph-120/240V Service Rated Nema 3R Automatic Transfer Switch. we are feeding the house with 400 amp to the meter then with splitting into 2 panels; in addition, I have line side taps with my 52 solar panel system; therefore, i was told a dualy.

​

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electrofelon said:
Is this (2) ATS's or a single unit with (2) 200's in it? If latter, then you have an issue with two service disconnects in a single enclosure.

Also I'm not clear on the (2) 200 ATS for a 26KW generator. Seems like with that size generator you should just switch one 200 amp set and keep the other one for non-generator loads 🤔
Click to expand...
Hello
Eddie702 said:
Used to be able to get homeowner permits in MA. I don't know whether they cut that out completely or not, but I know most inspectors will not issue homeowner permits.
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I know, i was given my solar pv permit in 2016 with no issues; the new wiring inspector is being too difficult and there is no law in MA that can make them deny it!
 
You are no longer allowed to have multiple service disconnects in a single enclosure, so that ATS wont fly. However, you may be able to exploit the emergency disconnect requirement and have the 2 200's in the ATS be emergency disconnects and not service disconnects. I assume you have a class 320/400A meter socket? IF so you can triple lug it and do you supply side PV connection there.

I still say its quite odd to have a 26KW generator feeding an entire 400A service. Are you doing any load shedding?
 
electrofelon said:
You are no longer allowed to have multiple service disconnects in a single enclosure, so that ATS wont fly. However, you may be able to exploit the emergency disconnect requirement and have the 2 200's in the ATS be emergency disconnects and not service disconnects. I assume you have a class 320/400A meter socket? IF so you can triple lug it and do you supply side PV connection there.

I still say its quite odd to have a 26KW generator feeding an entire 400A service. Are you doing any load shedding?
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Yes I do have a 320/400A meter socket! I may just add the 400 amp knife switch and call it a day; however.
We are building a 3 car garage with a living quarter for my son and his family; therefore, I cannot afford for them to be without power, and yes we are doing lots of load shedding, currently my ac mechanisms draw 7 amps total with soft starts, and my tesla charges disconnected!
Regards
 
sna1imj said:
Yes I do have a 320/400A meter socket! I may just add the 400 amp knife switch and call it a day; however.
We are building a 3 car garage with a living quarter for my son and his family; therefore, I cannot afford for them to be without power, and yes we are doing lots of load shedding, currently my ac mechanisms draw 7 amps total with soft starts, and my tesla charges disconnected!
Regards
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Ok jut remember it is code required that backup sources with ATS be able to serve the entire connected load and an inspector can ask for load calcs. As Larry and I have suggested, It probably makes more sense to have only one panel on the ATS - one generator panel, and one non generator panel. Put a nipple between them so you can tweak things as needed down the road.
 
By the way, I had 3 contractors come out to give me bids on the standby generators and they all said 20 to 22kw size while looking at all of my electrical panels to figure out the loads!
 
I had to retain a master electrician so I can finish my project due to legalities in our state, I drew all schematics and turnd it in to POCO and they were approved by them but the town has to pass
 
sna1imj said:
By the way, I had 3 contractors come out to give me bids on the standby generators and they all said 20 to 22kw size while looking at all of my electrical panels to figure out the loads!
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unless they do a load calc or can get usage from POCO then they are just guessing. Last 200 amp home I did he had a 32kw gen, luckily around here POCO has that information. Like electrofelon said, you going to need load shedding or have a dedicated gen panel
 
sna1imj said:
By the way, I had 3 contractors come out to give me bids on the standby generators and they all said 20 to 22kw size while looking at all of my electrical panels to figure out the loads!
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Yes, that size generator will probably run almost everything you have in practice, but it is required to meet the NEC calculated load which is 2-3 times what the actual load will be. IMO it is a ridiculous requirement for a non-legally required standby generator but that is the way it is.
 
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