Panel generator locks out legal?

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ritelec

ritelec

Senior Member
Location
Jersey
Is using a panel lock out that prevents the main breaker from being turned on when back feeding the panel with a 30amp inlet and breaker from a generator legal.
I see lockouts that are listed and not listed with a particular panel cover. If it's listed, can you use these lockouts to backfeed a 200 amp panel with a 30 amp generator? Or will it not be legal because the generator isn't sized for a 200 amp load even though it's on a 30 amp breaker? If it's legal great, if not would the only way wire a portable generator be by using one of those those sub panel transfer switches with 8 or 12 circuits and amp meters?
Thank you
 
Fred B

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
ritelec said:
Is using a panel lock out that prevents the main breaker from being turned on when back feeding the panel with a 30amp inlet and breaker from a generator legal.
I see lockouts that are listed and not listed with a particular panel cover. If it's listed, can you use these lockouts to backfeed a 200 amp panel with a 30 amp generator? Or will it not be legal because the generator isn't sized for a 200 amp load even though it's on a 30 amp breaker? If it's legal great, if not would the only way wire a portable generator be by using one of those those sub panel transfer switches with 8 or 12 circuits and amp meters?
Thank you
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The interlocking is not only legal (if listed) but mandatory if back feeding a panel, to prevent the possibility of feeding utility side when on generator power. As to the second part, a couple of considerations, if using a lower potential generator such as mentioned of the portable gen, load balance (L1-L2) is crucial as is identifying demand circuits load to prevent overload and damage to generator. That is part of the reason many would go with the subpanel transfer as most of that is addressed with the circuit limiting built into what or how many circuits are pulled into the transfer panel, although balancing the load still required.
The generator interlocking on main panel type also would require HO to make sure they monitor and control circuits on/off to prevent overloading generator each time it is used, whereas a transfer panel you (the electrician) would already predetermined that load and balance and they would simply transfer that load when using generator.
 
tom baker

tom baker

First Chief Moderator & NEC Expert
Staff member
Location
Bremerton, Washington
Occupation
Master Electrician
I thought that the manual transfer (breaker interlock) had to be listed, I didn't see that in 702.4(B). am I in the wrong section?
 
T

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
tom baker said:
I thought that the manual transfer (breaker interlock) had to be listed, I didn't see that in 702.4(B). am I in the wrong section?
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It is 702.5. In the 2107 and prior editions transfer equipment only need to be "suitable". Under the 2020 edition all transfer equipment (manual or auto) must be listed.
I wonder now if the listing requirement will require interlocking even if the panel cover is removed?
 
Seven-Delta-FortyOne

Seven-Delta-FortyOne

Goin’ Down In Flames........
Location
Humboldt
Occupation
EC and GC
Don’t think that’s compliant.

My understanding is that the interlock must physically prevent both sources from being active at the same time.

A lockout on the main panel would not accomplish that.
 
E

Eddie_T

Member
Location
Southern mtns near eastern continental divide
Occupation
PE (retired)
When talking about compliance one needs to consider whether it requires a permit to be pulled or if it will pass inspection. A temporary back feed requires neither and there is no roaming code police out there. A hazardous connection could cause insurance problems if damage occurs but I think none of us would create a hazard or fire danger. That's why I see no problem with my main disconnect lockout. I don't know what kind of lockout the OP was asking about. The one linked happens to fit my main breaker.
https://images-na.ssl-images-amazon.com/images/I/71VreCwpBcL._SL1500_.jpg
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
You need some type of listed transfer equipment which could be as simple as a breaker interlock kit. Just putting a lock on the main is not code complaint.
 
H

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Eddie_T said:
When talking about compliance one needs to consider whether it requires a permit to be pulled or if it will pass inspection. A temporary back feed requires neither and there is no roaming code police out there. A hazardous connection could cause insurance problems if damage occurs but I think none of us would create a hazard or fire danger. That's why I see no problem with my main disconnect lockout. I don't know what kind of lockout the OP was asking about. The one linked happens to fit my main breaker.
https://images-na.ssl-images-amazon.com/images/I/71VreCwpBcL._SL1500_.jpg
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More than insurance problems, criminal liability too. Our local poco has a lineman killed many years ago because the homeowner used a suicide cord to the dryer and didn’t turn off the main. Doing it and knowing the proper process is one thing, but unqualified people is where it gets dangerous.
 
E

Eddie_T

Member
Location
Southern mtns near eastern continental divide
Occupation
PE (retired)
You're right, the key word is unqualified. For 20 years I didn't have a lockout but now I am old enough to know that I could expire with the generator connected. The lockout would would be a caution to anyone else coming on the premises.

Of course my little generator would fail if the breaker were not open as it could not supply the neighborhood but it could send a spike before failing.
 
G

GerryB

Senior Member
Location
woodbridge, ct. USA
Eddie_T said:
You're right, the key word is unqualified. For 20 years I didn't have a lockout but now I am old enough to know that I could expire with the generator connected. The lockout would would be a caution to anyone else coming on the premises.

Of course my little generator would fail if the breaker were not open as it could not supply the neighborhood but it could send a spike before failing.
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I think you are missing the point some are making. If you are an electrician or apparently an engineer and you turn off your main and backfeed your service during an outage, it's irrelevant whether you lock your breaker or not, unless you think you will forget and turn it on while the genny is running.

But if you were a contractor hired to install some type of back up power or maybe you wanted to help a friend with a generator just a lock for the main breaker is not compliant.
 
R

robertd

Senior Member
Location
Maryland
Occupation
electrical contractor
Eddie_T said:
I don't use an interlock just a lockout on the main breaker. I have used it while utility workers were working on my feed and have never been questioned.
Click to expand...
What happens if you are not home, the power goes out and someone else starts up the generator?
 
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