Generator Interlock Kits

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infinity

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New Jersey
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Journeyman Electrician
If the generator used with the interlock kit is a listed portable generator, the failure would be based on 110.3(B).

Which part of 110 would specifically apply? And wouldn't that apply later when the generator is actually connected? For now an inlet box and an interlock would be compliant no?
 

don_resqcapt19

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Illinois
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retired electrician
Which part of 110 would specifically apply? And wouldn't that apply later when the generator is actually connected? For now an inlet box and an interlock would be compliant no?
The gernerator listing requires the use of transfer equipment that switches the grounded conductor.
 

don_resqcapt19

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retired electrician
Let's say for the sake of this thread there is no generator. Just an inlet box and a listed interlock, how does that violated the NEC?
Because the installation has only one use...to connect a portable generator to the buildings electrical system.

Also is the interlock listed as "transfer equipment"? 702.5 requires the use of "transfer equipment".
 

kwired

Electron manager
Location
NE Nebraska
Because the installation has only one use...to connect a portable generator to the buildings electrical system.

Also is the interlock listed as "transfer equipment"? 702.5 requires the use of "transfer equipment".

First sentence of 702.5: "Transfer equipment shall be suitable for the intended use and designed and installed so as to prevent the inadvertent interconnection of normal and alternate sources of supply in any operation of the transfer equipment."

Interlock kits meet this requirement, nothing in that article mentions listing requirements. I am open to suggestions of requirements if they have good backing, I just need more than what was presented so far on this one to convince me there is something wrong with it.

Where is it required that the neutral must be switched? If one were to install a genuine transfer switch I would guess 99% of the time it still wouldn't switch the neutral, but nobody would question it either.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Since when did the panel cover hold in the breakers? IMO if a plug on breaker will not stay attached to the bus without the cover, you have a weak connection waiting to make for additional problems.
That center rib of the panel cover holds the breakers "in place". I didn't mean to infer that it held a breaker securely in place. But, you can't remove the breaker with the cover on can you ?

BTW, I just remembered another reason why some inspectors won't allow interlock kits. I've had some tell me that they've seen instances where the main breaker did not disconnect from the utility when operated. "What if that happens ? "

IMHO, once you use that tiny little 2 letter word IF, anything can be possible
  • What IF the main breaker doesn't disconnect from the utility ?
  • What IF the main breaker only disconnected one phase ?
  • What IF a downed tree disconnects your triplex from the house and the POCO mis-connects when they power back up ?
  • What IF a plane crashes in your back yard and you lose power ?
  • What IF you won the $320 Mil lottery today and couldn't find your ticket ?

Anything is possible with IF
 

kwired

Electron manager
Location
NE Nebraska
That center rib of the panel cover holds the breakers "in place". I didn't mean to infer that it held a breaker securely in place. But, you can't remove the breaker with the cover on can you ?

BTW, I just remembered another reason why some inspectors won't allow interlock kits. I've had some tell me that they've seen instances where the main breaker did not disconnect from the utility when operated. "What if that happens ? "

IMHO, once you use that tiny little 2 letter word IF, anything can be possible
  • What IF the main breaker doesn't disconnect from the utility ?
  • What IF the main breaker only disconnected one phase ?
  • What IF a downed tree disconnects your triplex from the house and the POCO mis-connects when they power back up ?
  • What IF a plane crashes in your back yard and you lose power ?
  • What IF you won the $320 Mil lottery today and couldn't find your ticket ?
Anything is possible with IF

Including what IF a transfer switch fails to disconnect one line from the utility side?
Or what IF you turned off a breaker for servicing something and at least one pole never opened?

The dead front of a panelboard is there to close up the front side of the panelboard. It may help some in keeping breakers in place. I have mostly seen this need in FPE panels and GE 1/2 size breakers. (You get what you pay for)

The cover provides no securing in a panel with bolt on breakers.
 

don_resqcapt19

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Location
Illinois
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retired electrician
First sentence of 702.5: "Transfer equipment shall be suitable for the intended use and designed and installed so as to prevent the inadvertent interconnection of normal and alternate sources of supply in any operation of the transfer equipment."

Interlock kits meet this requirement, nothing in that article mentions listing requirements. I am open to suggestions of requirements if they have good backing, I just need more than what was presented so far on this one to convince me there is something wrong with it.

Where is it required that the neutral must be switched? If one were to install a genuine transfer switch I would guess 99% of the time it still wouldn't switch the neutral, but nobody would question it either.
The code section clearly requires the use of "transfer equipment" and goes on to describe the function of transfer equipment. While I fully agree that the interlock kit provides the required functionality of "transfer equipment" they are not transfer equipment unless so listed.

As far as the requirement to switch the neutral, it only applies to listed portable generators, 15kW or less used to supply power to a building. The requirement is found in the UL Guide Information for "Engine Generators for Portable Use" (FTCN). The requirement does not appear in the Guide Information for "Engine Generators" (FTSR). The generators covered by FTSR are intended for stationary and not portable use.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Including what IF a transfer switch fails to disconnect one line from the utility side?
Or what IF you turned off a breaker for servicing something and at least one pole never opened?

The dead front of a panelboard is there to close up the front side of the panelboard. It may help some in keeping breakers in place. I have mostly seen this need in FPE panels and GE 1/2 size breakers. (You get what you pay for)

The cover provides no securing in a panel with bolt on breakers.
Roger said:
However, it is not used in the NEC.
I agree with you both.:happyyes:
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
The code section clearly requires the use of "transfer equipment" and goes on to describe the function of transfer equipment. While I fully agree that the interlock kit provides the required functionality of "transfer equipment" they are not transfer equipment unless so listed.

As far as the requirement to switch the neutral, it only applies to listed portable generators, 15kW or less used to supply power to a building. The requirement is found in the UL Guide Information for "Engine Generators for Portable Use" (FTCN). The requirement does not appear in the Guide Information for "Engine Generators" (FTSR). The generators covered by FTSR are intended for stationary and not portable use.
This is the argument that jwelectric has posed and it's a valid argument. If we all accept this as being Gospel then there's no point in talking about interlock kits with listed generators under 15KW. By the same token you would not be able to use any of the Reliance transfer panels as they do not transfer the neutral. The only chance you might have is if they made a multi-switch transfer panel (similar in style to the Reliance units) with multiple EZ-generator switches like the ones shown here : http://www.ezgeneratorswitch.com/ . In this case you would have to hard-wire in each branch circuit as these switches transfer the neutral.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I know, it seems ridiculous right ? I once got a call from a customer after a storm and a downed power line. When POCO reconnected her they spliced both of the ungrounded conductors to the same phase. It was at a point on the utility pole where several other customers were also connected. The call I got was that her electric range didn't work.:roll:
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
This is the argument that jwelectric has posed and it's a valid argument. If we all accept this as being Gospel then there's no point in talking about interlock kits with listed generators under 15KW. By the same token you would not be able to use any of the Reliance transfer panels as they do not transfer the neutral. The only chance you might have is if they made a multi-switch transfer panel (similar in style to the Reliance units) with multiple EZ-generator switches like the ones shown here : http://www.ezgeneratorswitch.com/ . In this case you would have to hard-wire in each branch circuit as these switches transfer the neutral.
Note that this would only apply if you are using a generator of 15kW or smaller that is listed as a portable generator. In many states there is no requirement to use a listed generator and there are many portable generators that are not listed.
 
The only thing thay anyone ever cared about was the UL stamp/mark

The only thing thay anyone ever cared about was the UL stamp/mark

As long as the Interlock has a UL mark/stamp, which ALL of the ones made by the manufacturers SQ D, ITE or GE or Interlockkit.com have then my inspector said he would pass the install. And since that conversation I have installed over 30 of them!! The one interlock I won't use is the ones made by Natramelec.com and it is because he does not have the UL listing.
Can't tell you about Jersey, don't care!

Don

Interlock kits

UL listed interlock kits are accepted by licensed electrical inspectors as code compliant on installations that have been issued a permit by a municipality. (I think that covers it:D)

If they are not accepted in your area I would ask the inspector for a code section prohibiting them.[/QUOTE]
 

Terrier

Member
Location
Ohio, USA
Who gets thrown under the bus?

Who gets thrown under the bus?

Doing illegal un-permitted work so you can use equipment you seem to know they would turn down.

I fail to see the license making a difference.

Licensing may make a difference in the long run. As an elelectrial engineer (prone to relocation), but not a licensed electrician, I hire my contractor to do my electrical work, even though he and his subs may not pull a permit. If any of his work shows up as not meeting code during a home inspection, it will be him that gets thrown under the bus for any rework necessary.

Yes, all of his contracts say "includes all necessary permits and inspections" and "all work performed in accordance with current codes and standards."
 

Terrier

Member
Location
Ohio, USA
NEC 702.4 (B) System Capacity

NEC 702.4 (B) System Capacity

From my observation, may of the portable generators used by home owners are undersized for their full home loads. How do these accessories that effectively make the service pannel into a piece of manual transfer equipment, ensure compliance with 704.2(B)(1)?

702.4 Capacity and Rating

(1) Manual Transfer Equipment.​
Where manual transferequipment is used, an optional standby system shall haveadequate capacity and rating for the supply of all equipmentintended to be operated at one time. The user of the optionalstandby system shall be permitted to select the load connected
to the system.

Are we to assume the installers will provide adiquate instructions to the homeowners regarding the turning off of certian breakers to bring their load down to a level that their generator can serve? ... i.e., turn off the pool pump, sauna, AC, ... .

 

kwired

Electron manager
Location
NE Nebraska
From my observation, may of the portable generators used by home owners are undersized for their full home loads. How do these accessories that effectively make the service pannel into a piece of manual transfer equipment, ensure compliance with 704.2(B)(1)?

702.4 Capacity and Rating

(1) Manual Transfer Equipment.​
Where manual transferequipment is used, an optional standby system shall haveadequate capacity and rating for the supply of all equipmentintended to be operated at one time. The user of the optionalstandby system shall be permitted to select the load connected
to the system.

Are we to assume the installers will provide adiquate instructions to the homeowners regarding the turning off of certian breakers to bring their load down to a level that their generator can serve? ... i.e., turn off the pool pump, sauna, AC, ... .

If they are not informed, it doesn't take too long to figure it out, or worst case they end up paying for a service call to get educated on the matter.
 
Last one I installed came with red critical load stickers. I labelled the heat, fridge, sump pump, freezer, etc.

The rest of the panel is properly labelled (as per code) and I spent a few minutes explaining to them that they just spent roughly $1000 on a generator and if they don't want to kill it they can't act like they're running on utility power.

Maybe we should be required to give a comprehension test prior to pulling permits for interlock kits!:slaphead:
 
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