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Discussion Starter #1
I've just finished partially re-wiring my home. It was built in 1935. Originally had a 60 amp fuse panel on the main floor that was re-fed when a 100 amp breaker panel was installed.

I've recently installed a 200 A square D 60 circuit panel, replacing as much of the greasy old cloth wire as I could access. I currently have it temporarily fed from my old 100 amp panel until I do my underground service, which won't be until springtime at the earliest since I'm in Canada with frozen ground buried under 18 inches of snow already.


Cover On by xmptsunami, on Flickr

The reason for the increased service size is the garage that will eventually be built. Beside this garage I would like to install a nat. gas pad mount generator. I want a system that is easy to operate and safe.

I would like my generator to start automatically when power is lost and have my panel automatically switch over to generator power. For this I am using a contactor.


Generic Contactor Pic by xmptsunami, on Flickr

For those unfamiliar, this is a generic pic of a contactor. This one I believe is rated at 100 amps. This is not the type of contactor I need, but we'll get to that later.

How my panel currently looks on the inside:


Cover Off by xmptsunami, on Flickr

The extra length in wires will be trimmed off once I have finalized the positions of all the breakers.

This was the largest commonly available panel I could buy, with room for 60 regular breakers. My plan is to cut the buss bars, creating a split panel. The top 40 places will be fed through the main 200 amp breaker. The bottom 20 places will be isolated. I have already cut the buss bars.

The lower 20 places will be reserved for the loads I want powered during a power outtage. Freezers, lights, natural gas furnace, etc. While the service grid is live, the bottom section of my panel will be fed through 2 60 amp 2 pole breaker connected to the upper section of my panel. Between these breakers will be a sufficiently sized motor starter contactor. This will be a contactor with both normally open and normally closed contacts. The lower section will have power fed to it through the contactors normally closed contacts.

The normally open contacts will be used when the generator is running. The contactors coil will be energized by the generator.


Close-Up Painted by xmptsunami, on Flickr

The yellow box at the bottom is the contactor.
The green line is where I have cut my panel buss bars.
The orage and blue wires are tied to 60 amp breakers where the 60's are.
The pink wires are the feed in from the generator.


The neutral from the generator will always be connected to the panel's neutral, as will the ground.

With this system, even if the contactor welds itself to either sets of contacts I cannot backfeed power into the grid killing utility workers, nuns and orphans.

My panel will be visibly labelled as a split panel as obvious as I can make it. If I ever sell my house, which I don't plan to, the lower section of the panel will simply be removed and all the breakers located on the upper section of the panel. The next home owner can decide if he wants to leave it as is or restore it my way.
 

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Discussion Starter #2 (Edited)
I have not found a source for my contactor yet.

I am looking for a 2 (or 3) pole contactor rated at 100 amps, or a 4 pole contactor rated at 50 amps (which would have the contacts wired in parrallel).

This contactor must have both normally open and normally closed contacts.


I know this type of contactor exists because I have installed them at previous jobs. We were using them for underground central blasting where the blasting line had to remain shorted (through the normally closed contacts) until ready to blast. Then, through a timer, each level of the mine would, one at a time, blast using the normally open contacts.

This system was used so that geophones could detect each level of the mine blasting separately, and show which levels blast went off successfully and which lever did not blast. We were using 4 pole contactors rated at 60 amps (I think). The contacts were wired in series to aid in redundancy.


Help me find this contactor.
 

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Discussion Starter #4
The one you linked has only normally open main contacts. That is just a standard motor starter style contactor.

The contactor I need has both normally open and normally closed main contacts.

Similar to the auxilliary contacts found on the side of contactors, which uses one bar that is moved between a set of upper terminals and a set of lower terminals. This ensures that it cannot fail with both terminals energized.


I could use two reversing style contactors to do what I want, however with a setup like that, one of the contactors has to be energized 24/7 so when it fails, and it eventually will, I will be left without power. Reversing contactors that are mechanically interlocked also take up a lot of room and I want to locate everything in the bottom of my main service panel.
 

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So you need high current NO+NC, like a manual transfer switch. I have seen them, just forget where. Try Northern tool and Grainger.
 

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I am a electrician here In Louisiana. I always watch Holmes on Holmes and I always see the electric panels on there and its cool to see how yall bring your home runs into the panels like that all staples separatly. Looks good and neat. I like
 

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I am a electrician here In Louisiana. I always watch Holmes on Holmes and I always see the electric panels on there and its cool to see how yall bring your home runs into the panels like that all staples separatly. Looks good and neat. I like
x10

I am an Industrial DDC PM and really admire the art of some trades. Bending a ton a pipe into a huge MCC or a bunch a 1/2 inch into a breaker panel or Canadian Romex. (The one Holms=es show had a panel that looked upside down.

/Hijack
 

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Till you get done paying for this contractor.

Would you not be more cost effective to just get a transfer switch and be done.

Some of these contractors can get quite expensive unless you can get one for gratis.

Good luck .

it is a good idea
 

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My issue with cutting the bus bar and other wiring is it is not UL or Canada approved and there may be an issue when selling the house later on.
 

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Those contactors alone can be fairly expensive. With the money you're putting into this already I would just look into a whole transfer switch, they aren't all that expensive in the scheme of things and will be a cleaner install. If you're dead set on just the contactors cutler hammer makes all different ones. If you get a transfer switch you can pick up a used nicer unit with digital controls and run an annunciator inside or have it run periodic exercise sessions or there are much simpler ones. If you run a transfer switch large enough you can just run the whole panel off the transfer switch, but I'm sure there's a reason you've decided against a transfer switch. Good luck
 

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Automationdirect.com has cheap stuff. They may have a contractor for your application.
 

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This same Allen Bradley contactor was used for a pre charge contactor for a large Frequency drive used on the equipment I work on. It was quite common for the four 1/4-20 bolts that hold the armature together to loosen up and the contactor would not pull in square or would jam all together.
Granted the equipment I work on starts an average of one time a day but if I were you I would disassemble it and put loctite on the threads.

You will have to pull the movable contacts out to split get in that deep if the contactor is used make sure to mark the contacts and put it back together the same way.



do you really want to build an auto transfer switch? There are plenty to be had that are already approved.
A simple manual transfer switch can be done by back feeding a breaker in the panel and having a interlock that will not allow the main and the generator breaker to be energized at the same time.
I would have to look for where I picked up my interlock but it was only about 30 bucks and was simple to install.

As said don't cut the buss buss bars, I would just run a sub panel next to the one you put in for the loads you want on the generator.
 

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Discussion Starter #14 (Edited)
I am a electrician here In Louisiana. I always watch Holmes on Holmes and I always see the electric panels on there and its cool to see how yall bring your home runs into the panels like that all staples separatly. Looks good and neat. I like
x10

I am an Industrial DDC PM and really admire the art of some trades. Bending a ton a pipe into a huge MCC or a bunch a 1/2 inch into a breaker panel or Canadian Romex. (The one Holms=es show had a panel that looked upside down.

/Hijack
Thank you both. It really didn't take very long at all to arrainge the wires like this and was well worth it. Nobody cares if you charge an extra 1/2 hour to a job, but a shitty looking job gets remembered forever.

I have also just finished a garage done the same way for a friend.

Till you get done paying for this contractor.

Would you not be more cost effective to just get a transfer switch and be done.

Some of these contractors can get quite expensive unless you can get one for gratis.

Good luck .

it is a good idea
The price for the contactors are really very reasonable, especially when you consider that I don't need a separate enclosure, external wiring, connectors, and all the space I'm saving. Transfer switches are generally huge and take up even more room when you allow clearance for wiring.

My issue with cutting the bus bar and other wiring is it is not UL or Canada approved and there may be an issue when selling the house later on.
As I said in my first post, when I sell my home, I have the option of simply removing the bottom 1/3 of my panel. The plastic insulating mount for the buss bars are sectional and the bottom 1/3 simply removes with two screws leaving the panel looking completely normal, exactly like a 40 place panel. It will just have some breaker knockout fillers on the lower section of the cover.

Those contactors alone can be fairly expensive. With the money you're putting into this already I would just look into a whole transfer switch, they aren't all that expensive in the scheme of things and will be a cleaner install. If you're dead set on just the contactors cutler hammer makes all different ones. If you get a transfer switch you can pick up a used nicer unit with digital controls and run an annunciator inside or have it run periodic exercise sessions or there are much simpler ones. If you run a transfer switch large enough you can just run the whole panel off the transfer switch, but I'm sure there's a reason you've decided against a transfer switch. Good luck
I don't have nearly enough room in my electrical "closet" to install a transfer switch. I would have to locate it outside and show my wife how to operate it. Even getting to it in the winter would require some shovelling. The contactor will allow me a very nice, clean installation that is automatic and foolproof.

Automationdirect.com has cheap stuff. They may have a contractor for your application.
YES, they do. I was hoping you'd chime in on my discussion here. I found a very nice open style DPDT 40 amp relay here for only $19.99. I think it may be the ticket! See below.

Wow, I never thought I would see "briggs and straton" on an electrical panel. That looks like the best separate generator panel I have seen, since it uses two mechanically interlocked contactors to select which power source to use. It seems, though, that both contactors are the normally open sort, so one would have to be energized 24/7 and when the coil fails I would lose power. I still don't have enough room to install something like that.

This same Allen Bradley contactor was used for a pre charge contactor for a large Frequency drive used on the equipment I work on. It was quite common for the four 1/4-20 bolts that hold the armature together to loosen up and the contactor would not pull in square or would jam all together.
Granted the equipment I work on starts an average of one time a day but if I were you I would disassemble it and put loctite on the threads.

You will have to pull the movable contacts out to split get in that deep if the contactor is used make sure to mark the contacts and put it back together the same way.





do you really want to build an auto transfer switch? There are plenty to be had that are already approved.
A simple manual transfer switch can be done by back feeding a breaker in the panel and having a interlock that will not allow the main and the generator breaker to be energized at the same time.
I would have to look for where I picked up my interlock but it was only about 30 bucks and was simple to install.

As said don't cut the buss buss bars, I would just run a sub panel next to the one you put in for the loads you want on the generator.
I just included that photo to show those unfamiliar what a contactor looks like. I won't be using that exact style.

I did consider installing a mechanical interlock like the ones used on factory generator panels. The style with a piece of steel on a pivot that only allows one main breaker to be "on" at a time. This would be a very simple mod to add to my current panel cover, but, once again, it would rely on somebody actually turning on and off breakers, etc.


Metal Backfeed Breaker Interlock by xmptsunami, on Flickr

This is the relay I found on Grumpy's link. It uses a 120 VAC continuous duty coil, with two NO/NC contacts that share a common lug. The contacts are rated at 40 amps and since they use the same contact bar it cannot fail with both contacts closed at the same time. $19.99 :smokin:

http://www.automationdirect.com/adc/Shopping/Catalog/Relays_-z-_Timers/Electro-Mechanical_Relays/Power_Relays,_Open-Style,_40A_(AD-PR40_Series)/AD-PR40-2C-120A


Open Style 40 Amp Relay by xmptsunami, on Flickr

I've also finally contacted someone from my previous employer to find out the type of contactor we were using for underground blasting. The search term I was missing was "definite purpose" or "DP"


square D DPA34 contactor by xmptsunami, on Flickr

Readily available from about $49.99 and up.
http://www.pexsupply.com/Schneider-Electric-8910DPA34V02-30-Amp-120V-DP-Contactor

These DP contactors are used in HVAC applications. Square D makes a model DPA34 that used a single 240 VAC continuous duty coil to operate four separate 30 amp double break contacts. The purely resistive load rating is 40 amp. There are two NO and two NC contacts. This would allow me to use the two NC contacts to allow power through from the grid when the contactor is not energized and the two NO contacts to allow power through from the generator when it is running. Since all contacts are "break before make" style, it would be nearly impossible for the contactor to fail in such a way that power would be sent back into the grid, especially considering that the contacts would be opening and closing with nearly no load.

I've ran my entire house all summer on a temporary feed from a 40 amp breaker, excluding the central air unit and the clothes dryer. I don't think I would be even close to stressing 40 amp contacts. I would, however, use 40 amp breakers for this setup instead of 60s.
 

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If this screws up and kills somebody, are you aware you could be held criminaly responsible.
Wiring into the panel looks good though. I like the ideas you have, just try get it inspected by ESA after! It would probably never pass, because you dont have an approved bus bar once its been cut up!
 

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Factorymation Has all kinds of stuff like that.
 

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Use a commercially available auto-transfer switch. A 200A will mount in your room, they're really not that big.

You have a good idea, and it would work great. However, you're loosing all your UL/CUL listings, and that alone usually means it won't pass inspection. It also makes you liable for anything that happens. Theoretically the contactor should be nun/lineman safe. However, weird shit happens and failure can't ever be 100% predicted to happen any which way.

If you're buying the generator unit, it should have an optional transfer switch. If you're pony'n up the cash for the genny, spend the extra couple hundred $ on the listed switch (last cummins system I did was 1200A, and the transfer switch was about a $1K option when purchased with the genny). Then put it outside, in-line with your under-ground service and you're really not out any extra cash, while having a fully legal system (minus your bus-bars of course).

Have you looked at what generator you're using? What do they use for an automated control circuit? All the newer cummins stuff has basically a can-bus link between the generator and the ATS for start-up and power transfer/disconnect. A cummins tech has to show-up and do an initial programming and start-up on the computer for the ATS/genny. This applies for the small I4 chevy motors on propane/gas/nat gas up to the 30L I12 diesel industrial stuff. This means you need a complete system, not just the genny unless you want to sacrifice all the features you're paying for.
Not trying to scare you, but it makes a difference if you know what exact generator you're using.


And lastly, stop using those shitty metal staples! They're the source of many service calls. Harmonics cause the romex to wiggle under them, and they cut through eventually. The plastic ones may not look as nice, but romex never looks good anyways. I would have stubbed 6 or 8 1" or 1 1/4" pipes up and brought them all down in conduit if you really want to clean up the normal romex mess.
 
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