400A man transfer SW

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mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
Does a manual transfer sw (service rated) need the the secondary supply connected to pass an inspection? If the generator is to be installed at a later date can the XFER sw be installed? I would think it shoudl but then I think that anyone could install any size generator.

Woudl it make a difference if this were an automatic transfer switch since the generator has to be sized?
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
Does a manual transfer sw (service rated) need the the secondary supply connected to pass an inspection? If the generator is to be installed at a later date can the XFER sw be installed? I would think it shoudl but then I think that anyone could install any size generator.

Woudl it make a difference if this were an automatic transfer switch since the generator has to be sized?

If you already have pulled a permit for the genny install, then the transfer switch can pass, at least that is how it would work here.
 

ceb58

Senior Member
Location
Raeford, NC
Does a manual transfer sw (service rated) need the the secondary supply connected to pass an inspection? If the generator is to be installed at a later date can the XFER sw be installed? I would think it shoudl but then I think that anyone could install any size generator.

Woudl it make a difference if this were an automatic transfer switch since the generator has to be sized?

For a manual switch it should not matter since you could hook up a 5kw unit to the switch. Now if it were a ATS then I would say every thing must be in place to verify compliance with 702.5 B 2
 

mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
702.5 was my thought, I was just not sure how it may be enforced since some may want to do this install in stages. To be honest I was thinking of doing it on my own "future" house but did not want to purchase a new 15-20kw generator at the time of building a new house.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Locally, we inspect what you have installed.
It is fairly common to find the situation you describe, and the best we can do is advise that any future work should be inspected (a) because it's a State law, (b) it helps assure a safe installation, and (c) there can be heck to pay if it is not inspected.
 

kwired

Electron manager
Location
NE Nebraska
If a generator is to be installed later and local rules require permit and inspection for the installation of it then it is covered at that time.

We install panelboards with spare slots for possible future circuits don't we?

If you installed a 400 amp feeder and only connected 10 amps of load to it don't you think the inspector may think that something else will be added to it at some time?
 

ceb58

Senior Member
Location
Raeford, NC
Locally, we inspect what you have installed.
It is fairly common to find the situation you describe, and the best we can do is advise that any future work should be inspected (a) because it's a State law, (b) it helps assure a safe installation, and (c) there can be heck to pay if it is not inspected.

Would you pass a install of a ATS with out the Generator being in place? If I were the inspector I would not because there is no way to verify the generators load. If it were inspected without the gen. being there there is really nothing stopping the HO or a hack from installing a undersized generator. Unless the inspection department checks the house every week to see if it had been done. I doubt that is going to happen.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Would you pass a install of a ATS with out the Generator being in place? .
No (I should have clarified)

If I were the inspector I would not because there is no way to verify the generators load. If it were inspected without the gen. being there there is really nothing stopping the HO or a hack from installing a undersized generator. Unless the inspection department checks the house every week to see if it had been done. I doubt that is going to happen.

Exactly
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
Locally, we inspect what you have installed.
It is fairly common to find the situation you describe, and the best we can do is advise that any future work should be inspected (a) because it's a State law, (b) it helps assure a safe installation, and (c) there can be heck to pay if it is not inspected.

No (I should have clarified)



Exactly

Wow fastest 180 flip-flop in history! :)

IMO you can't fail an install without a good reason. Failing the install of a switch because of what someone might hookup is not reasonable. If they choose to install a non-code compliant genset after you leave and not get it inspected then they are breaking the law. It isn't your job to predict they won't get the rest of the work inspected. To me it is not any different than any other scenario where wiring, or boxes are put in for a future piece of equipment.

Beside if that was the plan they could just wait until after the inspect to put the switch in...
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
You are welcome to your opinion, but I try to follow the book.....

(2) Automatic Transfer Equipment. Where automatic transfer equipment is used, an optional standby system shall comply with (2)(a) or (2)(b).
(a) Full Load. The standby source shall be capable of supplying the full load that is transferred by the automatic transfer equipment.
(b) Load Management. Where a system is employed that will automatically manage the connected load, the standby source shall have a capacity sufficient to supply the maximum load that will be connected by the load management system.

My read is that "WHEN ATS equipment is used... the standby source", etc.
Once you install the ATS the source shall be capable is the way I read it.....


"Beside if that was the plan they could just wait until after the inspect to put the switch in... "
They can do that, but, in doing so, if they don't have it inspected they are in violation of the State Code for not having it inspected.
If an insurance company ever gets involved the consequences are not pretty.
 
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ceb58

Senior Member
Location
Raeford, NC
IMO you can't fail an install without a good reason. Failing the install of a switch because of what someone might hookup is not reasonable.

By that way of thinking an inspector could not fail you for not having the light switches in at final inspection. Well Mr. Inspector they dont know if they want standard,decor or slide dimers. We will get them later.
702.5 (2) says it shall comply with (2)a or (2)b. A ATS is unlike a panel with spare spaces that can be used at a later date. It it a device for a specific use. (2)a "The standby source SHALL be capable of supplying the full load that is transferred by the AUTOMATIC TRANSFER EQUIPMENT". I see no way an inspector can verify this with out the generator in place.
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
You are welcome to your opinion, but I try to follow the book.....

(2) Automatic Transfer Equipment. Where automatic transfer equipment is used, an optional standby system shall comply with (2)(a) or (2)(b).
(a) Full Load. The standby source shall be capable of supplying the full load that is transferred by the automatic transfer equipment.
(b) Load Management. Where a system is employed that will automatically manage the connected load, the standby source shall have a capacity sufficient to supply the maximum load that will be connected by the load management system.

My read is that "WHEN ATS equipment is used... the standby source", etc.
Once you install the ATS the source shall be capable is the way I read it.....


"Beside if that was the plan they could just wait until after the inspect to put the switch in... "
They can do that, but, in doing so, if they don't have it inspected they are in violation of the State Code for not having it inspected.
If an insurance company ever gets involved the consequences are not pretty.

ok I'll agree to disagree. But I also try to "follow the book"...
If there IS no source installed then how can a ref to the capacity of that source apply? And if there IS no employed system how can the installation fail because the system doesn't comply.

702.1 says the "The systems covered by this article consist of those that are permanently installed in there entirety" so 702.5 isn't applicable anyhow :grin:
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
By that way of thinking an inspector could not fail you for not having the light switches in at final inspection.

I don't believe this is a fair analogy. The ATS is installed for a future-use piece of optional equipment. When I did my work shop, before a did the dry wall I ran a circuit for a future welder I knew I wouldn't put in for around 6 months. The inspector can't possibly verify the circuit has the ampacity for the welder I am going to buy. Should he fail me because the circuit is already run?
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Two points..
In regard to the ATS, if it makes you feel better, we don't "fail" the job, we just don't pass it until it's complete (generator installed).
In reagard to the welder, this will probably ruffle your feathers also, but, since the conductor size is based on the welder duty cycle, if the welder is not there, the job remains open unless the conductor is protected at its ampacity.
 

kwired

Electron manager
Location
NE Nebraska
By that way of thinking an inspector could not fail you for not having the light switches in at final inspection. Well Mr. Inspector they dont know if they want standard,decor or slide dimers. We will get them later.
702.5 (2) says it shall comply with (2)a or (2)b. A ATS is unlike a panel with spare spaces that can be used at a later date. It it a device for a specific use. (2)a "The standby source SHALL be capable of supplying the full load that is transferred by the AUTOMATIC TRANSFER EQUIPMENT". I see no way an inspector can verify this with out the generator in place.

The OP is asking about a manual transfer switch not an automatic. It can be code compliant to connect a 1KVA or a 100KVA generator to this. Only requirement is that it be large enough to run what is intended to be run at one time with the operator selecting the load that is connected to the system (does not say how he should select it).
 

ceb58

Senior Member
Location
Raeford, NC
The OP is asking about a manual transfer switch not an automatic. It can be code compliant to connect a 1KVA or a 100KVA generator to this. Only requirement is that it be large enough to run what is intended to be run at one time with the operator selecting the load that is connected to the system (does not say how he should select it).

That is true and part of the OP's question was answered




Does a manual transfer sw (service rated) need the the secondary supply connected to pass an inspection? If the generator is to be installed at a later date can the XFER sw be installed? I would think it shoudl but then I think that anyone could install any size generator.

Woudl it make a difference if this were an automatic transfer switch since the generator has to be sized?

But the OP also ask about a ATS.......... so here we are:D
 

mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
I understood the issue with manual transfer switch so I added the ATS comment to debate the issues that have been brought up.
 
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