Main CB and Generator Interlock

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mkgrady

Senior Member
Location
Massachusetts
I hope to find a 3R 100 amp MCB panel with the fewest amount of spaces possible that I can install a generator feed to and a generator CB interlock. So that would be a 100 MCP panel with as little as four spaces. Due to space constraints it needs to be very small.

My plan is to connect the new panel to an existing 3R 100 amp meter/main. Connect the existing 100 amp load (that feeds the house) to a 2 pole 100 and connect a 30 amp 2 pole to the generator thru an inlet. The interlock is to prevent the 2 pole 100 and the 2 pole 30 from being on at the same time.

I can't do this the noraml way (at the main house panel, which is technically a sub-panel) because there just isn't any room to modify the existing panel and there is no space in it to add a generator CB.

Any ideas what panel and interlock might do the job?
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Cutler-Hammer makes a cover with generator interlock that fits there 8 to 12 ckt MLO panel.
I installed one recently and needed 15' x 15" if you have that much room.

It's in their CH series panels and i can find a Cat # if you are interested.
 
M

mkgrady

Senior Member
Location
Massachusetts
augie47 said:
Cutler-Hammer makes a cover with generator interlock that fits there 8 to 12 ckt MLO panel.
I installed one recently and needed 15' x 15" if you have that much room.

It's in their CH series panels and i can find a Cat # if you are interested.
Click to expand...

Thanks, I do have that amount of space and yes I would be grateful if you could post a cat#.
 
kwired

kwired

Electron manager
Location
NE Nebraska
masterinbama said:
Get the small 8 circuit Square D QO panel and one of these. It installs over ant 2 2 pole QO's. Graybar stocks them at their distribution centers.

http://products.schneider-electric....roductDetail&countryCode=us&partNumber=QO2DTI
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The 6 and 8 space panels although are 100 amp main lug panels only allow maximum of 70 amp breakers installed.

They do have a 4 circuit 125 amp panel that would work perfect along with the interlock kit.

Cat no for that panel is QO148L125GRB. Back feed one breaker as main, backfeed another as generator, supply feeder from main lugs.
 
augie47

augie47

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Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
I actually ordered a "Mechanically Interlocked Cover" for a 12 circuit Cutler Hammer C-H Style panel.
They are available for a number of different panel sizes. The catalog number of the cover I oedered was CH8BFM.

Fits Loadcenter
Catalog Numbers
Mechanical Interlock Panel Cover Catalog Number
Flush /Surface
A CH12L125B, CH16L125B, CH12L3125B, CH14B100B CH8BFM /CH8BSM
CH20L125C, CH24L125C, CH18L3125C, CH24L3125C, CH22B100C, CH22N100C CH8CFM/ CH8CSM
CH24L150D, CH32L150D, CH24L3225D, CH30L3150D CH8DFM /CH8DSM
CH42L225G, CH42L3225G CH8GFM CH8GSM
 
Dennis Alwon

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
mkgrady said:
Thanks to Kwired and Augie. Very helpful. I will look at the Square D and CH options
Click to expand...
I believe all the major manufacturers make them so check with your supplier to get the brand that they carry. I am pretty certain Siemens and Ge also make them.
 
S

SEO

Senior Member
Location
Michigan
As a note of caution when installing generator linkage kits make sure that you comply with section 408.36 (D) when backfeeding a breaker. This section is often overlooked when linkage kits are installed on the panel cover.
 
kwired

kwired

Electron manager
Location
NE Nebraska
mkgrady said:
I can't get the link to work. If it is the company I found a couple of years back that makes interlocks for lots of different panels I found them to be very expensive.
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They are expensive for what they are. Your alternatives are usually even more expensive. They have you right where they want you with their price.

Interlock kit is maybe around 50 bucks for most small frame breakers plus you need to buy a breaker for the generatar - maybe 12 dollars or so. That is a total of $62.00 for materials, and only takes maybe 15 minutes or so to install.

You can't even come close to that with a double throw switch and possibly additional breakers, disconnects etc if needed because the switch is not suitable for use as service equipment, and may take several hours to install.
 
kbsparky

kbsparky

Senior Member
Location
Delmarva, USA
Why not just mount an interlock kit in the meter/main box, and skip the intermediate panel?

I have one in my meter/main panel, with the inlet mounted in the side of the enclosure.
 
M

mkgrady

Senior Member
Location
Massachusetts
kbsparky said:
Why not just mount an interlock kit in the meter/main box, and skip the intermediate panel?

I have one in my meter/main panel, with the inlet mounted in the side of the enclosure.
Click to expand...

I would rather do that but the meter/main only has space for a main CB. There are no additional spaces for the generator CB.
 
kwired

kwired

Electron manager
Location
NE Nebraska
mkgrady said:
That worked and yes it is the company that I have used in the past. They are very expensive when compared to what the panel manufacturers now charge for their own version.
Click to expand...

Panel manufacturers typically only have their own version for their newer products. They are not all that cheap either in some cases. You probably will not find an OEM for a panel that is 30 years old or older, maybe even 20 years old in some cases.
 
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