automatic generator transfer switch wiring

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protec

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I was at a customers house doing electrical work.

When I opened up the 200 amp main breaker panel and 200 amp main lug sub panel along side of it I seen this.

Previous electrical contractor wired this automatic generator transfer like this.

They went from outdoor 200 amp meter main breaker to line side of 200 amp automatic transfer switch with 4/0 ser cable.

Then went from load side of auto transfer switch with 4/0 ser cable to the 200 amp main lug sub panel to the main lugs.

Thats where I was like you got to be kidding me?

It gets worse.

Then they installed a 100 amp 2 pole breaker in sub panel and wired it with #3 copper back to the line side of the 200 amp main breaker in main panel.

Totally wired it backwards.

I called the contractor out on it and he said it was safe and to code?

Come to find out no permit or inspection was done.

I see why?

Please give me you thoughts and feed back.

Thank you
 
You will see some unusual arrangements when generators are added. I see no glaring problem but would question if 702.4 was addressed
 
Is you concern that they went to the MLO panel first, because there is no main breaker in it? the generator should have the OCPD in it.
 
acrwc10 said:
Is you concern that they went to the MLO panel first, because there is no main breaker in it? the generator should have the OCPD in it.
Click to expand...
Instead of coming off the load side of transfer switch back to the 200 amp main breaker and panel like it should be done.
Makes no sense why he did it that way.
They ran it into the sub panel to main lugs first and installed a 2 pole 100 amp breaker in that panel to refeed with #3 copper back into the 200 amp main breaker in main panel that has all the bigger loads in it.
He is feeding a 200 amp main breaker with a 100 amp breaker with #3 copper???
#3 copper is not rated either for 200 amp service.
An old code teacher I had over 30 years ago said its a major code violation and fire hazard.
Whats your take on it?
Appreciate it.
 
protec said:
Instead of coming off the load side of transfer switch back to the 200 amp main breaker and panel like it should be done.
Makes no sense why he did it that way.
They ran it into the sub panel to main lugs first and installed a 2 pole 100 amp breaker in that panel to refeed with #3 copper back into the 200 amp main breaker in main panel that has all the bigger loads in it.
He is feeding a 200 amp main breaker with a 100 amp breaker with #3 copper???
#3 copper is not rated either for 200 amp service.
An old code teacher I had over 30 years ago said its a major code violation and fire hazard.
Whats your take on it?
Appreciate it.
Click to expand...
 
As long as the wire ran from the 100amp breaker is rated to carry 100amps I dont see the issue. You won't exceed 100Amps becuase the breaker protecting the wire will trip
 
171FIREFIGHTER said:
As long as the wire ran from the 100amp breaker is rated to carry 100amps I dont see the issue. You won't exceed 100Amps becuase the breaker protecting the wire will trip
Click to expand...
Why would you refeed the 200 amp main panel with a 100 amp breaker off sub panel where all your heavy loads are
It was rewired for generator backwards
 
protec said:
Why would you refeed the 200 amp main panel with a 100 amp breaker off sub panel where all your heavy loads are
It was rewired for generator backwards
Click to expand...
I dont do generators and can't tell you why they wired it the way they did. All I can tell you is when the generator is running the 200amp breaker in main panel will serve as nothing more than a disconnect.means.
 
acrwc10 said:
Is you concern that they went to the MLO panel first, because there is no main breaker in it? the generator should have the OCPD in it.
Click to expand...
bottom line is they rewired it backwards
the 100 amp sub panel is now wired as 200 amp main panel and the 200 amp main breaker panel with all the heavy loads is now the 100 amp sub panel???
 
I don’t see anything you’ve described as “a major code violation and fire hazard.”

It may not be best design, depending on what kind of loads are in each panel.

I have a feeling there’s more to this installation than we have been told. Example: is the generator sized to handle the entire house?
 
retirede said:
I don’t see anything you’ve described as “a major code violation and fire hazard.”

It may not be best design, depending on what kind of loads are in each panel.

I have a feeling there’s more to this installation than we have been told. Example: is the generator sized to handle the entire house?
Click to expand...
It is a code violation
They are using the sub panel for their main panel now and their main panel as a sub that has the A/C and dryer in it.
Would you install a 100 amp breaker in your sub panel to feed your main 200 amp breaker panel?
Forget about the generator part of the job.
This is how it is wired now during normal power?
 
protec said:
It is a code violation
They are using the sub panel for their main panel now and their main panel as a sub that has the A/C and dryer in it.
Would you install a 100 amp breaker in your sub panel to feed your main 200 amp breaker panel?
Forget about the generator part of the job.
This is how it is wired now during normal power?
Click to expand...
Nothing that was done changes the way it operates under normal circumstances. When Power company is providing the power the 200amp panel is still the main panel.

I honestly hope you are not getting this customer as upset as you appear to be. While their design choice was not the best nothing you have described is a code violation or a hazard
 
Last edited:
As noted in Post #3, unconventional, but we have no idea of situation when it was wired.
I agree with Retirede in that I see no "Major Code violation or fire hazard".
If you were inspecting it, what NEC Article would you cite as a violation ??
 
171FIREFIGHTER said:
Nothing that was done changes the way it operates under normal circumstances. When Power company is providing the power the 200amp panel is still the main panel.

I honestly hope you are not getting this customer as upset as you appear to be. While their design choice was not the best nothing you have described is a code violation or a hazard
Click to expand...
The original wiring was the 200 amp main breaker panel fed the sub panel with 100 amp
All the 220 heavy loads are still in main panel (a/c,dryer,etc..)
Now its wired backwards.
There was no reason to do this first of all.
100 amp sub panel is feeding the 200 amp main breaker panel now.
That is not a code violation???
Been doing this for 35 years.
My first code teacher I ever had said this is totally against code as well as the electrical inspector.
Was just seeing what other E-1 electricians thought.
 

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augie47 said:
As noted in Post #3, unconventional, but we have no idea of situation when it was wired.
I agree with Retirede in that I see no "Major Code violation or fire hazard".
If you were inspecting it, what NEC Article would you cite as
Click to expand...

protec said:
The original wiring was the 200 amp main breaker panel fed the sub panel with 100 amp
All the 220 heavy loads are still in main panel (a/c,dryer,etc..)
Now its wired backwards.
There was no reason to do this first of all.
100 amp sub panel is feeding the 200 amp main breaker panel now.
That is not a code violation???
Been doing this for 35 years.
My first code teacher I ever had said this is totally against code as well as the electrical inspector.
Was just seeing what other E-1 electricians thought.
Click to expand...
U
 
protec said:
The original wiring was the 200 amp main breaker panel fed the sub panel with 100 amp
All the 220 heavy loads are still in main panel (a/c,dryer,etc..)
Now its wired backwards.
There was no reason to do this first of all.
100 amp sub panel is feeding the 200 amp main breaker panel now.
That is not a code violation???
Been doing this for 35 years.
My first code teacher I ever had said this is totally against code as well as the electrical inspector.
Was just seeing what other E-1 electricians how is the 100amp sub panel feeding the 200amp main panel when generator is not running?
Click to expand...
 
So your telling me its code to feed the sub panel off load side of 200 amp meter main and use the sub panel with a 100 amp breaker to feed the 200 amp main breaker in main panel.
Your kidding?
 
protec said:
So your telling me its code to feed the sub panel off load side of 200 amp meter main and use the sub panel with a 100 amp breaker to feed the 200 amp main breaker in main panel.
Your kidding?
Click to expand...
As stated and asked, not desirable but what article and section would you cite?
 
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