Add main breaker to GE panel for generator interlock

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Old 09-05-08, 01:06 PM
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Add main breaker to GE panel for generator interlock

Hello Everyone,

Let me describe my setup. Outside, next to my electrical meter, I have a Square D 150 amp main breaker panel that feeds a 200 amp GE panel (TLM2020CCU) containing all of my branch circuits with no main breaker installed. This equipment was all installed within the last year by an electrician (used to have all Zinsco stuff)

What I'd like to do is add a main breaker to the GE panel (I think that's technically a sub-panel since there is no main breaker, right?) so I can add a generator interlock kit.

I'd prefer NOT to add one of those transfer switches that only allow you to run certain circuits off the generator. I feel that adding a main breaker to my GE panel and an interlock kit will:

1. Be cheaper than a transfer switch
2. Simpler to install
3. Give me more flexibility
4. Above all - still be safe and UL listed

My questions are:
1. Does this approach sound reasonable?
2. Can I install a 200 amp breaker in my GE panel in case I decide to upgrade my service down the road or do I need to install a 150 amp breaker? Keep in mind it is protected upstream by the 150 amp Square D main breaker.
3. What main breaker kit will I need for my GE panel?
4. I have installed plenty of branch circuits (and breakers) but never a main breaker. Is there anything special I should know aside from the obvious safety precautions (kill power at main breaker first, use no-ox on the aluminum service entrance cable, etc)?

Thanks for your help!

- Joe
 
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Old 09-05-08, 01:14 PM
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Joe, the reason you should/must use a transfer switch it takes the possibility of you backfeeding the main line out of the equation. With the setup you propose, there are too many "what ifs". What if you forget to turn off the main breaker when you power up your generator? What if the next owner of the house is unaware of your setup, since it will be a maverick setup at best? The transfer switches aren't expensive and although it causes you a little more work, it saves lives. In addition, unless you have a horse for a generator, you can't pull all the circuits in your house anyway, meaning you would have to go to the breaker panel and turn off certain areas that would overload the generator (more work). Not coming down, just wanting it done safely.
 
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Old 09-05-08, 01:19 PM
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Hi Chandler,

I'm well aware of the dangers of back-feeding the utility grid. The interlock kits I have seen prevent the breaker that is back-feeding the panel from the generator from being ON at the same time as the utility main breaker.

This company makes UL listed kits:
http://www.interlockkit.com/genelecmain01.htm

Are these kits not considered to be safe by the trade and NEC?

Thanks,

- Joe
 
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Old 09-05-08, 02:13 PM
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Originally Posted by joec2000 View Post
I think that's technically a sub-panel since there is no main breaker, right?
Yes it is a subpanel. The 150A panel is the main.

interlock kit will...
The interlock kit is usually cheaper than a full transfer setup. They do meet code for prevention of backfeed in most areas. I personally am a little concerned about the interlockkit.com products because they do not meet the requirement that the interlock system remain in operation when the panel cover is removed. You should talk to your local inspector before purchase, but most areas do accept them from what I understand.

1. Does this approach sound reasonable?
Yes, it is a common method of hooking up a standby generator.

Can I install a 200 amp breaker in my GE panel
Yes you may. Overcurrent protection is provided by the 150A breaker in the main. The main breaker in the subpanel acts only as a disconnect.

What main breaker kit will I need for my GE panel?
I would call the interlockkit folks and have them lookup the model number.

Is there anything special I should know aside from the obvious safety precautions (kill power at main breaker first, use no-ox on the aluminum service entrance cable, etc)?
Follow the torque requirements on the lugs and mounting screws.
 
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Old 09-05-08, 02:14 PM
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You would need to find the model number of the GE panel and see if it is field convertible from lugs to a main breaker. The label may have the info you need on the inside of the door. GE may make a interlock bracket to do the same thing.

I have heard that some areas will not allow the interlock that you linked to because it can be defeated by removing the panel cover. IMO this is really no diferent than other interlocks available, but you may want to check with your local inspection authorities.
 

Last edited by pcboss; 09-05-08 at 04:36 PM. Reason: spelling
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Old 09-05-08, 02:21 PM
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Thanks, everyone for your advice! I'll do some more research! You guys are great!

- Joe
 
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Old 09-05-08, 05:07 PM
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Many of the GE panels are convertibile so check with a GE supplier and see if yours is.
If so, it is a simple matter of removing two nuts and installing the main breaker with a hold down kit or screw.
GE has the interlock kits for most of their panels and they are less tha half the price of what Interlock sells.
We do use the Interlock equipment often.
It is UL listed for its purpose so don't worry about that.
True, interlock kits are not any good if you have the cover removed.
Check here:
http://www.geindustrial.com/publibrary/checkout/Application%20and%20Technical|DET-156A|PDF
 
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Old 09-05-08, 10:02 PM
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Here is the GE interlock kit:
http://www.geindustrial.com/publibrary/checkout/Application%20and%20Technical|DET393|generic
 
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Old 09-06-08, 12:09 AM
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Old 09-06-08, 09:18 AM
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Wow, that's fantastic! Any idea where a DIY guy could pick up one of these GE interlock kits? I'm assuming this isn't a home improvement store item, right?

I think I just lucked out... I found a 200 amp GE main breaker at the local Habitat For Humanity "Re-Store". It is labelled "22KAIC". They're asking $20 for it and it appears to be unused - the mounting screws are still taped to it in a little plastic bag. I'm trying to find out if my panel will accept this main breaker. The panel cover does not seem to list the compatible main breakers.

My panel does appear to have pre-drilled and tapped mounting holes for a main breaker kit.

Any ideas?

Thanks!!!!

- Joe
 
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Old 09-06-08, 11:46 AM
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Some of the HD stores have the GE kit.
Find an electrical supply house in your area that handles GE and you should be good to go.
 
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Old 10-02-08, 08:37 AM
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Hi everyone,

I have a follow-up question. I installed a 125 amp sub-panel outside to run my pool pump and A/C condenser. The panel is being fed by #6 wire and is protected by a 50 amp breaker in the load center in my garage (which is also technically a sub-panel since it currently has no main breaker).

To avoid having to run a whole separate line from the load center in my garage outside for the generator power inlet box, can I simply wire the generator power inlet box into the outdoor sub-panel I just installed? Is this code-legal?

Thanks,

- Joe
 
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Old 10-02-08, 02:39 PM
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No, since it is impossible to physically ensure that the inlet breaker and main breaker are not both closed, since the panels are at different locations.
 
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