Backup Generator Wiring

[RJM62]

I got the outside stuff done today:

I used 6-gauge THWN for the hots and common, and 10-gauge THWN for the ground (except in the box itself, which came with 6-gauge ground wires). I actually could have gotten away with 8-gauge THWN, but the cost difference was trivial and it gives me a bit of safety margin. It's a 50-amp circuit.

That's all I can do until the safety interlock comes in, which should be tomorrow. Then I can install the interlock, backfeed breaker, and inside wiring. I'll be using 6/3 Romex with ground for the interior wiring to the panel, mainly because I'm too lazy to run conduit. I also have to re-staple that coax I had to move.

Rich

 

[Half Fast]

Are you using one of these?

https://www.interlockkit.com/

 

[RJM62]

Are you using one of these?

https://www.interlockkit.com/

Yes, except I'm using the one made by Square D for my particular panel. Supposedly it's better to use the OEM panel maker's kit for some reason.

Rich

 

[MauleSkinner]

What size generator and how much of your house are you planning to be able to power?

I’m going to install a similar kit...just a 30-watt generator, so I’ll have to be pretty selective about what I can use on the generator.

 

[Half Fast]

What size generator and how much of your house are you planning to be able to power?

I’m going to install a similar kit...just a 30-watt generator, so I’ll have to be pretty selective about what I can use on the generator.

I’m guessing that’s a typo as I’ve never seen a 30W gen. That wouldn’t light up a 60W bulb.

 

[MauleSkinner]

I’m guessing that’s a typo as I’ve never seen a 30W gen. That wouldn’t light up a 60W bulb.

You are correct...3000W.

Maybe the 0 is too close to the backspace key...I hate typing with my thumbs!

(Although I DID say I’d have to be pretty selective. )

 

[RJM62]

What size generator and how much of your house are you planning to be able to power?

I’m going to install a similar kit...just a 30-watt generator, so I’ll have to be pretty selective about what I can use on the generator.

This is the generator:

https://www.samsclub.com/sams/sua12000e-12000w-generator/prod20940007.ip

Gets great reviews everywhere, and Sam's Club had the best price. The generator arrived a few days ago, but I didn't have the time to go pick up the THWN until today. The rest I was able to either buy locally or from Amazon.

The THWN is hard to find locally because most of the locals just run the Romex through the conduit right to the inlet switch, which was legal until (I think) 2007 or so. Now they want wire rated for wet areas in exterior conduit. UF-B is too bulky, so I went with THWN. It's a lot easier to work with.

That generator will easily power the critical stuff like the well pump and the furnace, and may power the air-conditioning. It's actually protected at 38A, so it's questionable. It should also power the electric range or the clothes dryer if I shut down other power hogging circuits for that time. It'll have no problems with things like the toaster over, microwave, and so forth if used judiciously.

So basically, I can't run everything in the house at the same time, but I can run the critical stuff with a few amps left over for discretionary use.

The advantage of the interlock rather than transfer switches is mainly cost. The interlock costs ~ $50.00, which is still overpriced for about 10 square inches of sheet metal and some screws and labels, but it's a lot less expensive and easier to install than transfer switches. You just use the main panel breakers to control which circuits get power. The other advantage is that you don't have to mess with the mains. Everything is done downstream of the main breaker.

Rich

 

[Half Fast]

This is the generator:

https://www.samsclub.com/sams/sua12000e-12000w-generator/prod20940007.ip

Gets great reviews everywhere, and Sam's Club had the best price. The generator arrived a few days ago, but I didn't have the time to go pick up the THWN until today. The rest I was able to either buy locally or from Amazon.

The THWN is hard to find locally because most of the locals just run the Romex through the conduit right to the inlet switch, which was legal until (I think) 2007 or so. Now they want wire rated for wet areas in exterior conduit. UF-B is too bulky, so I went with THWN. It's a lot easier to work with.

That generator will easily power the critical stuff like the well pump and the furnace, and may power the air-conditioning. It's actually protected at 38A, so it's questionable. It should also power the electric range or the clothes dryer if I shut down other power hogging circuits for that time. It'll have no problems with things like the toaster over, microwave, and so forth if used judiciously.

So basically, I can't run everything in the house at the same time, but I can run the critical stuff with a few amps left over for discretionary use.

The advantage of the interlock rather than transfer switches is mainly cost. The interlock costs ~ $50.00, which is still overpriced for about 10 square inches of sheet metal and some screws and labels, but it's a lot less expensive and easier to install than transfer switches. You just use the main panel breakers to control which circuits get power. The other advantage is that you don't have to mess with the mains. Everything is done downstream of the main breaker.

Rich

Also, most of the transfer switches only give you a limited number of circuits. With the interlock you just use your breakers in your main panel and have every circuit available for use (though not all simultaneously, of course).

 

[RJM62]

Also, most of the transfer switches only give you a limited number of circuits. With the interlock you just use your breakers in your main panel and have every circuit available for use (though not all simultaneously, of course).

Yes, although I'm told that you can install multiple transfer switches if you add some labeling to the effect of not exceeding X-number of amps. I didn't check that in the code, but an electrician told me.

It seems like a waste of money to me, though. The interlock is a much simpler solution.

Rich

 

[cowman]

I’m really interested in doing something like this but the one wrinkle is I’d like our heating system on it and there’s the rub. It’s a geothermal that takes two big 220 breakers that, IIRC are both 50 amp. Not a lot of generators out there that will work with although the actual current draw under normal operation is very low.... the second high amp breaker is for “emergency heat” which is just a big electric heater that kicks in if the geothermal has a problem or can’t supply enough heat for some reals. So maybe we could just not hook it up and run without? The controller box probably won’t like that though.

 

[Stewartb]

I used a licensed electrician and he got the required permit. The switch is easy. I have a male to male cord that connects my Honda 6000 inverter gennie to the switch box. The inverter gennie can handle 10,000 watts of surge so no issues with furnace or well, and I don't even unplug my electric hot tub. There's nothing better than a shower and a cup of coffee when the power's out and the neighbors are camping in their living rooms!

 

[RJM62]

I’m really interested in doing something like this but the one wrinkle is I’d like our heating system on it and there’s the rub. It’s a geothermal that takes two big 220 breakers that, IIRC are both 50 amp. Not a lot of generators out there that will work with although the actual current draw under normal operation is very low.... the second high amp breaker is for “emergency heat” which is just a big electric heater that kicks in if the geothermal has a problem or can’t supply enough heat for some reals. So maybe we could just not hook it up and run without? The controller box probably won’t like that though.

I don't know about that. It probably would report a fault and might shut down if it called for "emergency heat" and got nothing. Just turning off that breaker might cause a problem with the controller if it monitors that circuit for voltage. I suppose you'd have to ask the manufacturer.

Rich

 

[Unit74]

I used a licensed electrician and he got the required permit. The switch is easy. I have a male to male cord that connects my Honda 6000 inverter gennie to the switch box. The inverter gennie can handle 10,000 watts of surge so no issues with furnace or well, and I don't even unplug my electric hot tub. There's nothing better than a shower and a cup of coffee when the power's out and the neighbors are camping in their living rooms!

I resemble that comment! I’ve got a 3800 watt portable and no transfer switch. Just cords into the house! Maybe one of these days I’ll pay the man to Hotwire it in.....

 

[RJM62]

I used a licensed electrician and he got the required permit. The switch is easy. I have a male to male cord that connects my Honda 6000 inverter gennie to the switch box. The inverter gennie can handle 10,000 watts of surge so no issues with furnace or well, and I don't even unplug my electric hot tub. There's nothing better than a shower and a cup of coffee when the power's out and the neighbors are camping in their living rooms!

We don't have licensed electricians in Sparrow Fart. Literally anyone can be an electrician. The only requirement is an insurance policy that covers electrical work.

My friend across the street is an electrician, and I offered him the job. But he hasn't had the time because for once, construction and renovation are busy here. So I decided to just do it myself. It's a pretty simple job. 240V tends to scare people for some reason, but wiring is wiring. I just follow the codes and double-check everything. I've never had a DIY electrical job fail an inspection.

Rich

 

[Greg Bockelman]

Yeah, Rich. Nothing really mysterious about electricity but it seems to scare most everyone.

 

[Stewartb]

Up here backup gennies are common and so are electocuted linemen. Backup gennies have to have code-compliant transfer switches to protect the guys in the boom trucks on those windy nights.

Up here the big line in the sand is automatic or manual connection. Auto requires a consumption worksheet and something like 1.5 maximum draw for the Gennie. Manual allows us to choose which circuits to energize. I don't touch my breakers, the gennie runs the house just fine.

 

[RJM62]

Up here backup gennies are common and so are electocuted linemen. Backup gennies have to have code-compliant transfer switches to protect the guys in the boom trucks on those windy nights.

The interlock is an acceptable alternative in most jurisdictions. It makes it physically impossible for the service main and the backfeed from the generator to be energized simultaneously. I think they're a great idea. People are much more likely to spend $50.00 than a grand to keep things safe. It encourages people to do the job safely rather than backfeeding through their clothes dryer plugs like many people do.

All the interlock is is a slider that prevents the service main breaker and the backfeed breaker from being in the "ON" position at the same time. You have to turn the currently energized breaker off and slide the interlock to turn the other breaker on. It also has a bracket that prevents the backfeed breaker from being easily removed, presumably because it takes the place of the main breaker while it's in use, so it has to be attached to the panel. And of course, it has about half a dozen safety labels.

Some jurisdictions require that the interlock be made by the same company as the panel. My jurisdiction isn't one of them, but it might be in the future, so I bought the OEM one.

The only thing I haven't decided yet is how I'll rig something to know when the utility power is back. For various code reasons, you can't just hook up a light to the service mains. Even if it's circuit-protected, you can't have more than one connection per lug. They do have an inductive indicator that wraps around the insulated part of the main and sidesteps the code, but I think I'll wait until an actual outage to see if there's some indicator on the meter I can glance at.

Rich

 

[NHWannabe]

This is the generator:

https://www.samsclub.com/sams/sua12000e-12000w-generator/prod20940007.ip

Gets great reviews everywhere, and Sam's Club had the best price. The generator arrived a few days ago, but I didn't have the time to go pick up the THWN until today. The rest I was able to either buy locally or from Amazon.

The THWN is hard to find locally because most of the locals just run the Romex through the conduit right to the inlet switch, which was legal until (I think) 2007 or so. Now they want wire rated for wet areas in exterior conduit. UF-B is too bulky, so I went with THWN. It's a lot easier to work with.

That generator will easily power the critical stuff like the well pump and the furnace, and may power the air-conditioning. It's actually protected at 38A, so it's questionable. It should also power the electric range or the clothes dryer if I shut down other power hogging circuits for that time. It'll have no problems with things like the toaster over, microwave, and so forth if used judiciously.

So basically, I can't run everything in the house at the same time, but I can run the critical stuff with a few amps left over for discretionary use.

The advantage of the interlock rather than transfer switches is mainly cost. The interlock costs ~ $50.00, which is still overpriced for about 10 square inches of sheet metal and some screws and labels, but it's a lot less expensive and easier to install than transfer switches. You just use the main panel breakers to control which circuits get power. The other advantage is that you don't have to mess with the mains. Everything is done downstream of the main breaker.

Rich

Have had a similar set up for the past 10 years and love it. The few times we've had to use it we have loved the flexibility of choosing what we need to power and when by shutting a breaker and opening the one we need.

Plan is to get rid of this generator and get an electric start model, nothing worse than trying to pull start a generator that's been sitting in an unheated garage in the middle of a New Hampshire winter. If we get a Winter Storm Warning for a Nor' Easter I'll put a shop light underneath the generator and covering it with a heavy duty moving blanket.

 

[MauleSkinner]

The only thing I haven't decided yet is how I'll rig something to know when the utility power is back. For various code reasons, you can't just hook up a light to the service mains. Even if it's circuit-protected, you can't have more than one connection per lug. They do have an inductive indicator that wraps around the insulated part of the main and sidesteps the code, but I think I'll wait until an actual outage to see if there's some indicator on the meter I can glance at.

Rich

That's something I hadn't thought of...at our previous house I had a separate generator box with a few critical circuits, so when the power came back on, everything else lit up.

I’m not anticipating nearly as many power outages at this house, and the neighbors are close enough that I’ll probably see their houses light up.

 

[3393RP]

I don't know about that. It probably would report a fault and might shut down if it called for "emergency heat" and got nothing. Just turning off that breaker might cause a problem with the controller if it monitors that circuit for voltage. I suppose you'd have to ask the manufacturer.

Rich

It should be possible to lock out the emergency heat if system thermostat has that capability.

 

[Jim Rosenow]

You do nice work, Rich!

A parallel question for you master electricians, if Rich will permit the digression....

Our house was wired for a generator when we built it.... transfer switch/lock-out, etc with a lead to a 4-prong 220 box on the outside wall like Rich has. Works great with our 10kw gen. I got inquisitive the other day with all the storms, and realized that running the 10kw for 24 hours will burn a BUNCH of gas (we have no natural gas or LP tank).

So...I came up with plan B. A little Honda 2kw gen will run most of the stuff we need most of the time (all LED lights, one fridge, one freezer), and just sip fuel. Was thinking of getting one of those and only running the big gen when more power is needed for a short period (cooking, heating water, etc), in a prolonged outage.

The problem is getting juice from the 110 plugs in the little gen thru the 4-prong receptacle on the outside wall to the breaker box (after turning off all the 220 stuff in the breaker box of course). I suspect there's no commercially-available cable for this, as it's somewhat unique to our situation. I resist the double-ended male plug cord to a 110 outlet 'solution', although I hear that works, if you turn off the main breaker first.

Thoughts? Thanks!

Jim

 

[FastEddieB]

I’m researching something basic right now, in order to have backup power available to open the bifold door on our new home.

It requires 220v @ 30A. Hence, this should work:

Handy that itcome with a receptacle for a generator cord built in.

Doing the math, looks like I need at least a 6,000 watt generator.

Whole-house would be nice someday, but will have to wait.

 

[RJM62]

You do nice work, Rich!

Thanks!

A parallel question for you master electricians, if Rich will permit the digression....

Our house was wired for a generator when we built it.... transfer switch/lock-out, etc with a lead to a 4-prong 220 box on the outside wall like Rich has. Works great with our 10kw gen. I got inquisitive the other day with all the storms, and realized that running the 10kw for 24 hours will burn a BUNCH of gas (we have no natural gas or LP tank).

So...I came up with plan B. A little Honda 2kw gen will run most of the stuff we need most of the time (all LED lights, one fridge, one freezer), and just sip fuel. Was thinking of getting one of those and only running the big gen when more power is needed for a short period (cooking, heating water, etc), in a prolonged outage.

The problem is getting juice from the 110 plugs in the little gen thru the 4-prong receptacle on the outside wall to the breaker box (after turning off all the 220 stuff in the breaker box of course). I suspect there's no commercially-available cable for this, as it's somewhat unique to our situation. I resist the double-ended male plug cord to a 110 outlet 'solution', although I hear that works, if you turn off the main breaker first.

Thoughts? Thanks!

Jim

I'm no master electrician. That being said, the only safe way I know of to get 240V from a 110V generator is with a step-up transformer, and it will come at the cost of a loss due to energy converted to heat in the transformer. Personally, I'd just split the circuits into groups with a transfer switch if I wanted them on separate generators.

Rich

 

[MauleSkinner]

You do nice work, Rich!

A parallel question for you master electricians, if Rich will permit the digression....

Our house was wired for a generator when we built it.... transfer switch/lock-out, etc with a lead to a 4-prong 220 box on the outside wall like Rich has. Works great with our 10kw gen. I got inquisitive the other day with all the storms, and realized that running the 10kw for 24 hours will burn a BUNCH of gas (we have no natural gas or LP tank).

So...I came up with plan B. A little Honda 2kw gen will run most of the stuff we need most of the time (all LED lights, one fridge, one freezer), and just sip fuel. Was thinking of getting one of those and only running the big gen when more power is needed for a short period (cooking, heating water, etc), in a prolonged outage.

The problem is getting juice from the 110 plugs in the little gen thru the 4-prong receptacle on the outside wall to the breaker box (after turning off all the 220 stuff in the breaker box of course). I suspect there's no commercially-available cable for this, as it's somewhat unique to our situation. I resist the double-ended male plug cord to a 110 outlet 'solution', although I hear that works, if you turn off the main breaker first.

Thoughts? Thanks!

Jim

Get a smaller 220V generator. Don't make it more difficult than you have to.

 

[Bell206]

+1 on the interlock. Around here an electrician required to install transfer switch per code at would have cost $900 or so switch included. The interlock is also per code but I did the install with a similar type receptacle outside and it cost less than $250 complete. Was also told to purchase an interlock made for your panel. Mine is Siemens and cost $50 at local supply store. I have a B&S 8KW gen and did a complete load analysis. By sequencing the CBs I can get the house AC online and everything else which runs at about 22-24 amps or about 75% total load on gen.

Siemens lock installed:

 

[Jim Rosenow]

Thanks!
I'm no master electrician. That being said, the only safe way I know of to get 240V from a 110V generator is with a step-up transformer, and it will come at the cost of a loss due to energy converted to heat in the transformer. Personally, I'd just split the circuits into groups with a transfer switch if I wanted them on separate generators.
Rich

I didn't explain myself well...my bad. What I'm wondering is it if's feasible to jury-rig a cable to pass the 110 gen output thru the 220 receptacle (using just 3 of the four terminals) to get 110 to the breaker box for distribution. Don't want to try to get 220 from the little gen. Further reflection tells me that would probably only power one 'leg' of the box, anyway.

MauleSkinner....good idea, but I've been unable to find a 2kw-range gen that's capable of 220, as many 220 appliances would require more than 2kw. If I go larger than that, I'm headed back to the original big- gen gas consumption.

Probably the easy way is just run a 110 extension cord to inside the house from a little gen, and split off from there to power what I want. Not as elegant, but It will, after all, be in an 'emergency' situation.

Thanks!

Jim

 

[Half Fast]

I didn't explain myself well...my bad. What I'm wondering is it if's feasible to jury-rig a cable to pass the 110 gen output thru the 220 receptacle (using just 3 of the four terminals) to get 110 to the breaker box for distribution. Don't want to try to get 220 from the little gen. Further reflection tells me that would probably only power one 'leg' of the box, anyway.

MauleSkinner....good idea, but I've been unable to find a 2kw-range gen that's capable of 220, as many 220 appliances would require more than 2kw. If I go larger than that, I'm headed back to the original big- gen gas consumption.

Probably the easy way is just run a 110 extension cord to inside the house from a little gen, and split off from there to power what I want. Not as elegant, but It will, after all, be in an 'emergency' situation.

Thanks!

Jim

That would only energize half of your breakers.

The main feed coming into your house is 220V. Your breaker box puts half that, 120V, onto each half of the box, but it sends the entire 220V to things like your dryer, your hot water heater, your stove, etc. (This is over-simplified, but essentially correct.)

The bigger issue, though, is that this sort of "backfeed" can be dangerous, to you and to linemen, if you don't know what you're doing. The nature of your question makes me think you don't know much about home wiring, so please don't try this.

 

[Sac Arrow]

That would only energize half of your breakers.

The main feed coming into your house is 220V. Your breaker box puts half that, 120V, onto each half of the box, but it sends the entire 220V to things like your dryer, your hot water heater, your stove, etc. (This is over-simplified, but essentially correct.)

The bigger issue, though, is that this sort of "backfeed" can be dangerous, to you and to linemen, if you don't know what you're doing. The nature of your question makes me think you don't know much about home wiring, so please don't try this.

Presumably, he (RJM62) is feeding two-phase 220V from the generator to the main feed, hence the distribution between 220 and 110 should take care of itself in the breaker box. With the appropriate interlock, and wired correctly it should be safe.

Power in the distribution grid normally comes as three phase 480v, and the two phase legs will usually be split between housing blocks to even the load. Three hots = 480V, two hots = 240V, and hot to neutral = 110V.

 

[Half Fast]

Presumably, he (RJM62) is feeding two-phase 220V from the generator to the main feed, hence the distribution between 220 and 110 should take care of itself in the breaker box. With the appropriate interlock, and wired correctly it should be safe.

Power in the distribution grid normally comes as three phase 480v, and the two phase legs will usually be split between housing blocks to even the load. Three hots = 480V, two hots = 240V, and hot to neutral = 110V.

What RJM62 is doing is perfectly fine. I was responding to Jim's idea "... to jury-rig a cable to pass the 110 gen output thru the 220 receptacle (using just 3 of the four terminals) to get 110 to the breaker box for distribution.

 

[Sac Arrow]

What RJM62 is doing is perfectly fine. I was responding to Jim's idea "... to jury-rig a cable to pass the 110 gen output thru the 220 receptacle (using just 3 of the four terminals) to get 110 to the breaker box for distribution.

I see. Ouch. That won't work for a couple reasons.

 

[Stewartb]

I didn't explain myself well...my bad. What I'm wondering is it if's feasible to jury-rig a cable to pass the 110 gen output thru the 220 receptacle (using just 3 of the four terminals) to get 110 to the breaker box for distribution. Don't want to try to get 220 from the little gen. Further reflection tells me that would probably only power one 'leg' of the box, anyway.

MauleSkinner....good idea, but I've been unable to find a 2kw-range gen that's capable of 220, as many 220 appliances would require more than 2kw. If I go larger than that, I'm headed back to the original big- gen gas consumption.

Probably the easy way is just run a 110 extension cord to inside the house from a little gen, and split off from there to power what I want. Not as elegant, but It will, after all, be in an 'emergency' situation.

Thanks!

Jim

https://www.yamahamotorsports.com/generator/models/ef7200de-d

 

[Jim Rosenow]

What RJM62 is doing is perfectly fine. I was responding to Jim's idea "... to jury-rig a cable to pass the 110 gen output thru the 220 receptacle (using just 3 of the four terminals) to get 110 to the breaker box for distribution.

I agree completely it's a bad idea to input thru a normal 220 receptacle...or even 110 for that matter. Possibly I wasn't clear that the proposed receptacle is already a dedicated generator input, backed by an either/or transfer switch, similar to RJM's. We currently use it with the 10kw gennie. It would never be possible to send power to the grid thru it.

https://www.yamahamotorsports.com/generator/models/ef7200de-d

I appreciate your looking, Stewartb, but that uses almost as many gph as our current 10kw unit.... .86 gph. The 2kw units are down around .11 gph.... which lead to the original question

So...and this has become a logical exercise only...... the little gen has two 110 outlets. How about taking a hot lead off of each, and a single neutral and ground, and putting those thru the four terminals on the 220 receptacle...power to both sides? There's only a single fuse on the little gennie, so both outlets would be on the same circuit from that end. Educate me

Jim

 

[Sac Arrow]

I agree completely it's a bad idea to input thru a normal 220 receptacle...or even 110 for that matter. Possibly I wasn't clear that the proposed receptacle is already a dedicated generator input, backed by an either/or transfer switch, similar to RJM's. We currently use it with the 10kw gennie. It would never be possible to send power to the grid thru it.



I appreciate your looking, Stewartb, but that uses almost as many gph as our current 10kw unit.... .86 gph. The 2kw units are down around .11 gph.... which lead to the original question

So...and this has become a logical exercise only...... the little gen has two 110 outlets. How about taking a hot lead off of each, and a single neutral and ground, and putting those thru the four terminals on the 220 receptacle...power to both sides? There's only a single fuse on the little gennie, so both outlets would be on the same circuit from that end. Educate me

Jim

Ground wise, that could be a disaster. But, depending on the type of generator, that may or may not work in theory. A 220/110V generator most likely generated the current as three phase power, and split the 220 phase for the 110 circuit just like the actual house feed would. A 110 only generator probably generated the current as DC then inverted it, so the effect of joining the two hot leads would not have the effect of creating 220 since they are both in the same phase, having been split from the same line.

 

[Ted]

We have a 20kW generator (so 90A @ 220VAC) that has its own panel and feeds one of the two 200A panels (we have 400A service). Auto switchover and autostart. After having lived with it for 3 years and been visiting friends when the power is out at their house with portable generators, the auto switch is the way to go.

I really do not enjoy electrical, but I also just wired up my garage. Some 40 new outlets (I did all the boxes as double gang) located all over. I will never be wanting for a place to plug something in in the garage. 2-2-2-4 aluminum cable (it was $50 for 50 ft on a remnant) to feed the 125A panel (run through a wall and into the basement from the 1st floor), lots of conduit...

Rich, looks like good work on your side. I would enjoy that more than what I did.

 

[Greg Bockelman]

ALUMINUM cable?!? I didn’t know you could get that crap anymore.

 

[Ted]

ALUMINUM cable?!? I didn’t know you could get that crap anymore.

Yep, they still sell it.

It wasn't my preference and I know enough about electronics to know that I'd prefer copper. Plus, that was a real pain to deal with especially running through the PVC conduit and through the wall. 3-3-3-5 copper would've been much easier.

But for the price, I figured it was worth it, and I still think so.

 

[SoonerAviator]

I didn't explain myself well...my bad. What I'm wondering is it if's feasible to jury-rig a cable to pass the 110 gen output thru the 220 receptacle (using just 3 of the four terminals) to get 110 to the breaker box for distribution. Don't want to try to get 220 from the little gen. Further reflection tells me that would probably only power one 'leg' of the box, anyway.

MauleSkinner....good idea, but I've been unable to find a 2kw-range gen that's capable of 220, as many 220 appliances would require more than 2kw. If I go larger than that, I'm headed back to the original big- gen gas consumption.

Probably the easy way is just run a 110 extension cord to inside the house from a little gen, and split off from there to power what I want. Not as elegant, but It will, after all, be in an 'emergency' situation.

Thanks!

Jim

Have you actually calculated the fuel consumption with a light load on the 10kw genny? I only ask because if you aren't running it at 70-80% load, it's not going to drink fuel at a high rate. Sure, if you've got the dryer or other 220V items running it'll drink the fuel, but if you're just powering a fridge, a few lights/tv . . . it shouldn't make much of a difference I wouldn't think.

 

[RJM62]

All done and load-tested. Works great. Basically, it will power anything in the house -- just not all simultaneously.

Here are some more pictures.

Here's the junction of the Romex to the THWN. You have to use wire rated for wet areas in an exterior conduit. I chose THWN because it's less bulky than UF. It's also THHN rated, so I technically could have gotten away with 8-gauge from the junction box to the generator inlet. But I used 6-gauge anyway (except for the ground, which is 10-gauge) for a bit of extra safety margin and future-proofing.

I have to label this box.

Next picture is the backfeed breaker.

Next picture is the contraption to affix the backfeed breaker to the panel. This is required by code, presumably because the backfeed breaker becomes the "main" when in use. The label is also required by code.

The next picture is the interlock switch installed. It's a simple device. It physically prevents the backfeed and main breakers from being energized at the same time. That makes it impossible to energize the power company's lines (and possibly electrocute a lineman) from your generator. The labels are required by code.

And here's the little generator powering the house.

As I mentioned, with this setup, I can power anything in the house. I just can't power everything at the same time. It's a good setup if you have enough common sense to manually manage your power use.

Rich

 

[chartbundle]

ALUMINUM cable?!? I didn’t know you could get that crap anymore.

It's always been common for heavy gauge service wires. But annoyingly even more non-electrical wiring is starting to come as aluminium if you're not careful, I'm seeing 'CCA' (Crappy Crappy Aluminium, er, Copper Coated Aluminium) pop up more and more for things like speaker wire and network cable. Needless to say you don't want this stuff anywhere near a network that you want to be usable.

 

[Jim Rosenow]

Have you actually calculated the fuel consumption with a light load on the 10kw genny? I only ask because if you aren't running it at 70-80% load, it's not going to drink fuel at a high rate. Sure, if you've got the dryer or other 220V items running it'll drink the fuel, but if you're just powering a fridge, a few lights/tv . . . it shouldn't make much of a difference I wouldn't think.

Problem is the 10kw gennie isn't designed to throttle down....steady 3600 rpm. Since I got on this kick a few days ago, I've been running the big one some, with just a little load directly attached, and even with light load I'm guessing I've gone thru 2 gallons in 3 hours of use. On the up-side, we've had the big gennie 7 years, and haven't had an outage long enough to plug it in, so it's doing it's job.

Nice job Rich!!!!

Jim