# SquareD Generator Interlock Kit



## velvetfoot (Jul 13, 2008)

I am going to install a SquareD Generator Interlock Kit.
It is a easy way to safely connect a portable generator to the house wiring.
I am putting on an outside receptacle as well.
I thought I would share this because I didn't realize it existed before.
It's a cheap alternative to something that could be potentially life-changing expensive.
http://static.schneider-electric.us/docs/Electrical Distribution/Load Centers/Accessories, Homeline (HOM, LK, PK, QOM)/40273-809-02.pdf

Of course, I will likely avoid all outages after installing, knock on wood.


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## Highbeam (Jul 14, 2008)

I have had mine installed, passed inspection, and ready for work since sometime last year. It is a fantastic and cheap way to transfer the whole house to generator power safely and legally. 

In my case I was changing out the panel anyway so I had the new panel equipped with the interlock tab so that the UL sticker is valid. I used a 30 amp "generator" circuit and the connecticut electric outside receptacle with the same twistlok connector as my generator uses. 

No, I won't be running the electric water heater or the range but I will be running the fridge, microwave, coffee pot, lights, TV, etc. from their normal switches.


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## velvetfoot (Jul 15, 2008)

Cool!  It sure seems like a good solution.
While I'm waiting for the kit to arrive, I put on the outside receptacle, a 30 amp model by Reliance, with that same twist lock connector that my generator uses.  I am using the higher capacity 8 gauge wire inside the house, like the kind the electric range uses, versus the 10 gauge that could have been used.  The wire to the generator is 10 gauge.

For me, the deep (450') well pump is the big user.  I tried to run it with my 5kw generator and it wouldn't work, a scary experience to me as I visualized all those dollar bills flying out the window.  The compact flourescent lights went out and the kill-a-watt meter read 80 volts on one leg, and the pump seemed to have tripped out after a very short while and it seems to be normal since.  I got a clamp on ammeter and measured 37 amps surge and 11.7 amps steady state!  My other 7.5 kw generator ran the pump.

I figure, pick the spots to run the water pump.  Other loads include yours and for me the oil-fired boiler.  

I wouldn't know the minimum to run the generator to keep food cold enough though.  Maybe an outside digital thermometer (with a wire) could be used, with the sensor on the inside of the freezer section and the gauge on the outside.


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## jebatty (Jul 15, 2008)

Newer refrg's and freezers take very little electricity to run and are pretty easy on start-up. I use a 5500 watt generator to power some general lighting circuits (all CFL's), the 240v deep well pump, the sewer lift pump, refrig, freezer, microwave kitchen outlet circuit, and the outlet circuit that runs the computer (so I can keep up on the latest posts to the Hearth Forums). No problem at all.

When needed we run the generator about 1 hour every 4 hours.


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## velvetfoot (Jul 15, 2008)

That is interesting Jim.  I don't think voltage drop was a factor at the time going to my well pump, but who knows.  
Maybe my new setup will be better, but I just don't think my 5kw generator's 6kw surge capability was enough to get that motor turning (with 37 amps=8800 watts).
I'd prefer to use the lower wattage unit if only to save fuel.  Plus, I want to 'save' the good one, lol.
Perhaps use the bigger one once to take showers and fill a bathtub with water.

The only broadband we can get where we live is cellular wireless (verizon aircard), and of course it's not really broadband.
I have a feeling though that even if land lines go down, even if the cell towers have power, the network might become overloaded.


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## Highbeam (Jul 15, 2008)

We usually lose our coaxial feed during power outages which means loss of network television, land line phones, and internet during a power outage. So our entertainment options are reduced but we make due with movies and such. We have a good time all hunkered down in the stove room. 

I have run my old tecumseh 11HP powered 5500 genset in the past during outages and found it to be a major gashog even when lightly loaded. 0.5 gallons per hour lightly loaded and loud as heck. So when it died I replaced it with a physically smaller (I can pick it up), quieter, and more fuel efficient genset that I can use for camping as well. Only 3500 max running watts though so I can't weld with it but the fuel consumption reduction is very positive. Oh and to be sure, anyone thinking about using an interlock MUST have a 220 volt generator. You need both phases. 

I used the cheap 10-3 romex to run my generator circuit and the breaker is 30 amps, the twistlok is rated for 30 amps. Everything is 30 amps. If I had a critical appliance (well pump) that needed 37 amps then I would have upsized the wire. I have a couple of other heavy gauge runs at 50 and 60 amps that use the big wire and that material is very expensive and much harder to work with than 10 gauge.


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## velvetfoot (Jul 15, 2008)

You might be thinking of the aluminum stuff.  This was stranded copper (alloy?) and it's not too bad to work with.


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## Highbeam (Jul 15, 2008)

6 gauge copper romex, 6-3, at 3$ per foot for 50 -60 amp cuircuits. It was much heavier per foot and much stiffer than the 10 gauge which was much much cheaper. I would have suffered through it and done it with the 6-3 in your situation. I ran two long 6-3 circuits, one for a 50 amp welder and one for a 60 amp hot tub. It is rated for 55 amps but you are allowed to use the next larger standard breaker. 

So you really want to make a single run with the 6-3 wire from the panel to your outlet or whatever. When you need to run 80 feet to the outlet, you need to drag that 80' roll of 6-3 through the attic, through the crawlspace, over the rafters, etc. and it get's heavy really fast. Hard to pull through conduit too. Smarter guys use stranded but then you need to use conduit.


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## velvetfoot (Jul 15, 2008)

For me, it was all basement and then come out under a porch, and it was only a 50 foot roll which was 94 bucks at the hardware store (maybe they didn't have the latest commodity price on it  ).

What's interesting to me is that there's that 10 gauge orange romex going to that well pump, fed from a 20 amp breaker.
I guess it can take some surge before it trips.  I don't know anything about the specifics of your average breaker.


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## Highbeam (Jul 15, 2008)

That's a good price for 6 gauge romex. Maybe it has gone down recently with the bizarre economy. 

10 gauge is good for 30 amps whether 220 or 110, so you really have some oversized wire which is a good thing. I believe you're right that the breakers are "slow blow" to some extent to allow for surge loads like when you kick on that well pump.


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## velvetfoot (Jul 16, 2008)

Ooooops.  It's 8 gauge, so I probably paid the going rate.  

I figure it's a little over 10 gauge, so it can't hurt.


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## velvetfoot (Jul 18, 2008)

Here are some pictures.
I didn't take a closeup of the bracket that holds the breaker in, but it is in the picture of the kit.
Easy to install.  Had to make room in the upper two right breakers.


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## moosetrek (Dec 1, 2009)

If you're going to the trouble of installing an interlock and switch, you might want to go with at least a 50-amp receptacle and 6-ga.  If the future, you might want to run a larger generator and $ adds up every time you put in a new receptacle, etc.  That was the first thing installed in our "new" home (after the woodstove of course).  Added a plug in for the generator.  There is no interlock, so I'll have to label it "aux power outlet" when we sell so no future owner does anything dumb.  We have two trips - a main at the house and a second on the pole in the driveway.  As has been mentioned, you can't just feed one leg of the panel @110V; you might do bad things to some expensive appliances like the well pump/range/furnace.  Also, check the quality of the $80 generators - I'm not sure you want to run computers or sensitive electronics off them.  Finally, the frigge and freezer don't need much juice - if the power goes out open the freezer once to move stuff you need to the fridge/freezer and then leave it closed; if full it's safe for a long time before it'll warm up too much.  Use the fridge/freezer (or outdoors in winter) to keep stuff cool and run that off the gen.  Good luck!


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## fbelec (Dec 2, 2009)

you need to have a interlock kit to be up to code. and beside how would you feel if you forgot to switch something and killed the lineman trying to do a repair. the transformers on the pole take 5000 volts down to 120/240. if you backfeed that transformer with 120/240 you get 5000 out the other side. if you don't have anything like a well pump or electric stove 10/3 romex is fine. surge ratings are hard to find out per appliance unless you do a amp probe reading under normal conditions. 10/3 will actually hold 40 amps but the nec code book says for housing it's rated at 30 amps. you need to check what you inlet on the outside of the house will take for wire size. if you have a 30 amp plug and run 6 gauge and break off strands of wire to fit, under a heavy load it may overheat and melt. cheap way out if you going to run a larger size wire than you need run 6/3 ser aluminum. and then splice smaller wire size with a burndy connector for alum and copper. 6 gauge will not fit into a 30 amp breaker. alum wire is cheap.

startup current on motors is a killer. some oil burners depending on the motor used will draw 30 to 50 amps on startup then drop down to 5 amps. some older fridges can draw high teens for startup current and then drop to 4 or 5 amps. air conditioners. older window units 12000 btu runs at 12 amps. i've seen them take 30 to 50 amps on startup. central air conditioner condensors (outside unit) 3 ton runs at 16 amps startup 50 to 70 amps. 5 ton runs at 24 to 28 amps startup 100 to 115 amps. on a 50 amp 2 pole circuit breaker. their made for surge current


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## Highbeam (Dec 2, 2009)

That's great fbelec. My electric stove uses a 40 amp breaker but I can certainly run it with my little 3500 watt genset. Like anything else, you need to manage your power needs and it is easy on the oven by only using the range burners one at a time. I cooked up my top ramen noodles while my kids watched TV during the last outage. The small burners use a very low percentage of that 40 amp oven breaker and I barely noticed the load on the genset.

Trouble with these modern glass top electric ovens is that the element is either on or off and it cycles to give you the heat setting you set with the dial. So, your genset will be getting loaded and unloaded over and over as the elements cycle.


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## moosetrek (Dec 3, 2009)

fbelec said:
			
		

> you need to have a interlock kit to be up to code. and beside how would you feel if you forgot to switch something and killed the lineman trying to do a repair. the transformers on the pole take 5000 volts down to 120/240. if you backfeed that transformer with 120/240 you get 5000 out the other side. if you don't have anything like a well pump or electric stove 10/3 romex is fine. surge ratings are hard to find out per appliance unless you do a amp probe reading under normal conditions. 10/3 will actually hold 40 amps but the nec code book says for housing it's rated at 30 amps. you need to check what you inlet on the outside of the house will take for wire size. if you have a 30 amp plug and run 6 gauge and break off strands of wire to fit, under a heavy load it may overheat and melt. cheap way out if you going to run a larger size wire than you need run 6/3 ser aluminum. and then splice smaller wire size with a burndy connector for alum and copper. 6 gauge will not fit into a 30 amp breaker. alum wire is cheap.
> 
> startup current on motors is a killer. some oil burners depending on the motor used will draw 30 to 50 amps on startup then drop down to 5 amps. some older fridges can draw high teens for startup current and then drop to 4 or 5 amps. air conditioners. older window units 12000 btu runs at 12 amps. i've seen them take 30 to 50 amps on startup. central air conditioner condensors (outside unit) 3 ton runs at 16 amps startup 50 to 70 amps. 5 ton runs at 24 to 28 amps startup 100 to 115 amps. on a 50 amp 2 pole circuit breaker. their made for surge current



I'd recommend the interlock if you're going to do a proper install.  I didn't sweat it because a) I'm the only one that will use the generator and b) we have a 1926 house that was a rental/foreclosure - believe me, the interlock is the last code concern I have; the bare live wires in the basement when we moved in, the 3K wats on a 15A circuit, the wires electrical taped together in a wood chase, etc., all seemed more critical to bring to code.  Home wiring by homeowners is a chancy thing (says I, a homeowner and DIY-er!); especialy when you get into 220 and feeding a panel vs simply replacing an outlet or light...  Take the time and put it in right, it sounds like you have good knowledge and tools to do it.


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## fbelec (Dec 4, 2009)

been a master electrician for twenty years

on the electric stoves the small burner is 1500 watts the big burners are 2000 or 2500 depends on the model of stove. and the ovens are 3000 or 3500 watts depending on the stove model. to boil water for tea and the like it's quicker to use the stove than the microwave. and microwaves take 1200 to 1800 watts, depends on the model. on microwaves if the unit says 1200 watts cooking power that is not what it draws, it draws more. maybe about 300 more than cooking wattage. 

i had a guy call me for a price on hooking up his generator to his panel. he wanted to hook in a 5000 watt gen to run his electric hot water (4500 watts) his well (1200) his fridge, hot air oil burner and some lights. needed to keep exotic birds warm. i didn't get the job, but i think he bought himself a 7500 watt gen. if he goes in for a shower he going to be stretching that 7500 watt. wouldn't budge for a bigger one. up here in mass there has been a big push for home generators after the last december storm that put out the lights for 3 to14 days. we have a storm like this every 10 years :-/


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## Highbeam (Dec 5, 2009)

Fbelec, do you know if the range top burners are pulling the 1500-2500 watts from both phases, meaning 220 volts, or is it a 110 load? In managing power it is good to have balanced loads on each 110 leg of the genset. I would guess that it is a 220 load but not sure. Since the oven is a 4 wire hookup I can't tell easily.


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## fbelec (Dec 5, 2009)

highbeam their all a 240 volt load. so a 1500 watt burner at 240 volt would be 6.25 amps.
a electric oven pulling 3500 watts is 14.6 amps
not to bad. it's easier on the generator to heat water on the stove than a 1500 watt microwave.


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## Badfish740 (May 11, 2010)

I'm reviving this blast from the past in order to ask for help from all of you electrical geniuses out there.  The interlock kit that VF found is a great solution, but can someone walk me through the wiring from the generator receptacle outside to the panel?  I did a little online window shopping and found the following parts from McMaster-Carr that should do the trick as far as getting the power from the generator to the house:

http://www.mcmaster.com/#catalog/116/773 

First of all what would be the proper type of cable for wiring from the receptacle through the basement to the panel?  This wiring would be exposed (not sure if that matters or not) as the portion of the basement it will run through is unfinished.  The outside wiring will be pretty straightforward as I'll only really be making a male/male extension cord about 10' long.


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## Highbeam (May 11, 2010)

You won't be making a male/male extension cord. Your wall mounted outside power "inlet" will have male prongs sticking out. Your house becomes an appliance that you plug into your genset. The male outlet is available at Home Depot and you plug into it from below in sort of a drip proof fashion. The cord that runs from the hosue to the genset will be female on one end and male on the other. Mine are both twistlock 30 amp plugs and I plug them into each other for storage. 

The wiring from the outlet to your panel will be just like any other circuit in the home. I used a 30 amp breaker for my generator infeed so I needed 10/3 romex, stapled and routed just as any other wire in the home. You can use any sized wire that you want so long as it is big enough to pass as much current as the panel's generator infeed breaker allows.


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## fbelec (May 12, 2010)

what highbeam said. also
depending on the kit you buy, and panel brand you have, you can only put in a kit that is ul approved for that panel brand you have. the generator breaker will have to be mounted on the top of all the existing breakers in either the 1+2 spot or the 1+3 or 2+4 depends on your panel. that will interlock with your main breaker or as simple as moving the top 4 breakers to the bottom of your panel to make room for the generator breaker that will be interlocked with the breaker across from it which will be your new main breaker. if you have a 200 amp service the interlock kit has to be for the 200 amp panel you have. no other interlock kit will work because a 200 amp breaker takes 4 spots in the panel and that would not leave any room for your generator breaker. if this is the case you will need to install a 2nd panel next to the main panel with it's main being a 100 amp breaker in the top spot across from the generator breaker. this panel will have all critical circuits in your house you want running on the generator. and this is the panel that will have the interlock kit.
hope that is understandable  

frank


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## Badfish740 (May 12, 2010)

Highbeam said:
			
		

> You won't be making a male/male extension cord. Your wall mounted outside power "inlet" will have male prongs sticking out. Your house becomes an appliance that you plug into your genset. The male outlet is available at Home Depot and you plug into it from below in sort of a drip proof fashion. The cord that runs from the hosue to the genset will be female on one end and male on the other. Mine are both twistlock 30 amp plugs and I plug them into each other for storage.



I get what you're saying.  The only reason I suggested a male/male cord was because it felt weird to have a male end a receptacle on the house.  It doesn't matter to me one way or the other-does NEC specify?  



			
				Highbeam said:
			
		

> The wiring from the outlet to your panel will be just like any other circuit in the home. I used a 30 amp breaker for my generator infeed so I needed 10/3 romex, stapled and routed just as any other wire in the home. You can use any sized wire that you want so long as it is big enough to pass as much current as the panel's generator infeed breaker allows.



Gotcha-thanks!



			
				fbelec said:
			
		

> what highbeam said. also
> depending on the kit you buy, and panel brand you have, you can only put in a kit that is ul approved for that panel brand you have. the generator breaker will have to be mounted on the top of all the existing breakers in either the 1+2 spot or the 1+3 or 2+4 depends on your panel. that will interlock with your main breaker or as simple as moving the top 4 breakers to the bottom of your panel to make room for the generator breaker that will be interlocked with the breaker across from it which will be your new main breaker. if you have a 200 amp service the interlock kit has to be for the 200 amp panel you have. no other interlock kit will work because a 200 amp breaker takes 4 spots in the panel and that would not leave any room for your generator breaker. if this is the case you will need to install a 2nd panel next to the main panel with it's main being a 100 amp breaker in the top spot across from the generator breaker. this panel will have all critical circuits in your house you want running on the generator. and this is the panel that will have the interlock kit.
> hope that is understandable



I have a 200 amp Square D box so I'll just have to double check that they have the proper interlock to fit it.


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## Highbeam (May 12, 2010)

I have a 200 amp panel that came with an interlock. The main utility power comes in from the top, not sure why it matters that your panel is 200 amp but surely it is wise to check that the interlock kit will fit. 

Double male cords should always be prohibited, even a simple guy like me can see that they are a bad idea. The proper way to do this is with a male inlet on the house. My system was actually inspected and approved. 

Figure that you should never have utility power available at the generator power inlet and if you put a female plug there then someone, someday, will be ticked off that they can't plug their welder into it and try and bypass the interlock device.


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## fbelec (May 12, 2010)

there are kits that will fit any panel as long as it's a 100 amp main panel or i should say the main breaker that is 100 amp or less. 200 amp gen panels are great. they allow everything to be in one panel. but the kits allow for generator use with existing panel. and to meet code the kit has to be UL listed for that panel. 

they make the the house generator plug a male because if the generator cord was the male there is a chance that people forget them selves and start the generator then plug in the cord and now the male end of the cord has live prongs and could her the user

if you can't find a kit that will work in a square D panel then you'll have to do a sub panel setup.
and remember before installing the kit double check the papers that come with it to make sure that the kit will work in your panel.

this is all for code. if something happens and it was not code then the trouble begins.


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## fbelec (May 13, 2010)

just got a look at this at the supply house. this looks like a good one that is rated for most panels out there.

http://www.interlockkit.com/


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## willworkforwood (May 13, 2010)

I'm sure these interlock kits work great, if there's enough room in your panel.  My 100A panel was too packed to add anything else, so I bought a manual transfer switch from Reliance that's also a subpanel.
Connected them with a 50A breaker and #6 (short run, side-by-side). .  I moved all of the "required" circuts into the new T/S subpanel, and it worked out great.  The T/S comes prewired with specific locations on the bus for the main panel feed, and also for the genset feed.  A short run of #10 to a watertight 30A inlet box completed the install, and I use a 20' extension cord from the genset to the box.  I'm not a pro, but felt comfortable doing this job myself.  Cost of the T/S and box was just under $300.  The comment on the oven from Fbelec above caught my eye.  I didn't put the oven circut into the T/S, figuring it would draw too much.  But now I see that it wouldn't be a big deal at all - just don't run everything togeather.  Think I'll move it over this Summer (happy Wife happy life).


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