Generator to back feed house from garage

[thickhead]

Can I use my 5500 watt portable generator to feed power to my house from my garage about 50ft away?

Details:
-30 amp 240v circuit in garage for lift with a plug
-50 amp breaker (I think its a 50) in house panel to feed small box in garage
-portable 5500W continuous generator (~23 amps)
-everything at the house & garage has been installed by a pro.

Is it legal?
Is it safe if main is off?
Do I need to add anything?

 

[ChaseDE]

Someone will chime in here and correct me if I'm wrong, off the top of my head you should be able to backfeed the house and keep the fridge and other necessities running I think.

I have a regular generator, not sure the size/power but it's about 80lbs and 2' x 3' x 2' gas powered.

I made a backfeed cable for it and plug it into my clothes dryer 220 plug to backfeed our house when needed.

Yes make sure you turn off the main breaker/connection to the grid before you do that.

It may be illegal, I believe it is here in Delaware.

It works fine and has saved my food and families sanity plenty.

 

[Davefr]

I've done it a few times in the past but not anymore. The right way is to install a transfer panel. (or plug your appliances/tools directly into the generator)

If you backfeed, there's no room for error.
- You need to disconnect the main breaker so you don't backfeed the incoming power line which can put others at risk.
- You need to sequence throwing breakers so you don't overload the generator.
- The generator cable is male on the output side! If the generator is running and you touch the prongs you can be dead.

There are too many things that can go wrong backfeeded an entire circuit. In addition, conditions that require emergency power are usually at their very worst. (ice storms, windstorms, etc).

The bottom line is that you may be stressed out/tired in these conditions and have to perform the backfeed procedure with no room for error. That's a bad (and possibly deadly) combination.

Just get a transfer switch. It's so much easier/safer.

 

[exranger06]

No, not legal or safe. 1st of all, you cannot use an outlet for the lift. Doing so would involve using a "suicide cord," which is a cord with male plugs on both ends. You would have to make the cord yourself, since no company would make such a dangerous product. That alone makes this unsafe, but there's also the issue of backfeeding. If you want the generator to feed the house, you cannot feed it from the garage. The reason is there is no interlock to prevent the house from backfeeding to the grid. If you remember to turn off the main breaker at the house, it won't backfeed, but what if you forget? A proper installation will not let the generator energize anything unless the main is already turned off. The proper way to connect the generator is to add a circuit to the main panel at the house, and use an interlock kit that will either allow the generator's breaker to be turned on, OR the main breaker to be on (not both at the same time).

 

[yeldogt]

I can't imagine anyway it would be legal.

If everything else is done by a pro why not have a proper temp system installed ?-- transfer and connection point by the meter.

Have it done so if you want to do an automatic later you have the connection point.

 

[ChaseDE]

I definitely don't want to start an argument, I really don't even want to say I am right or backup my position. But on a forum where we do some pretty complex things, even easy but potentially dangerous things if not done right, brakes on a car, suspension jobs, re-wiring an entire garage, plumbing air lines with PVC (haha)....

Is it really THAT hard/dangerous/unacceptable to 1. turn off the main breaker and 2. plug the cord in before you start the generator?

I certainly understand everyone has their opinions/limits on what is illegal and ok and what is illegal and not ok as well.

Just sayin'

 

[BrendanBehan]

If done correctly and with proper gauge cable then it's OK. Highly frowned upon by the power companies because someone always does it wrong.
Tips:
Work out the proper sequence in advance when the weather is good. Test out everything including panel switches shunting, cable hookup, generator starting, and which breakers will be turned on and when.
Write down this connect/disconnect sequence and put a copy on your inside breaker, outside box, and even your generator. Make it so clear that anyone can follow it if you are away. Test the process yearly.

Remember that non inverter generators must be run at full throttle. I would not trust many of these generators to run my electronics which sometimes includes newer furnaces.

 

[theoldwizard1]

Is it really THAT hard/dangerous/unacceptable to 1. turn off the main breaker and ...

If you forget to do this, you will, at a minimum be attempting to power the grid at least up to the break in the line.

WORST CASE, YOU CAN KILL A LINESMAN ! The voltage leaving your house will eventually hit a transformer and then you will have some significant HIGH voltage.

 

[theoldwizard1]

Do I need to add anything?

Yes, add 4 more appropriately sized wires to the conduit from the house to the garage and wire them into a generator interlock breaker kit in your main panel.

 

[exranger06]

OP asked if it was legal. There is only one correct answer to that, and that's no, it's not legal. Legal/illegal is not an opinion. There are written rules. If you don't follow them, you're doing something illegal, regardless of your opinion. OP also asked if it's "safe." I explained why it's not safe, but if OP accepts the risks and takes measures to avoid them, then ok, that's on him. All I can do is explain the reasons why it's not safe. It's up to the OP to decide if he's capable of mitigating the risks and decides to do it this way anyway.

 

[Bigbandguy]

Without commenting on the legality.. if you are reasonably competent with matters electrical then yes it is possible. Suggest putting a reminder on the generator .. a big tag that says " Do NOT start unless main breaker is off" That way you and other persons would be reminded to make sure about that main breaker. Also it might save your generator from being fried if the main power came back on while it was running. There are so many generators now that linemen who wish to live a long time are probably checking for back feed BUT you cannot depend on that .

Even a manual transfer switch would be safer.

 

[Davefr]

Is it really THAT hard/dangerous/unacceptable to 1. turn off the main breaker and 2. plug the cord in before you start the generator?

No, it's not hard/dangerous if a precise procedure is followed.

The problem is that the procedure is totally unforgiving to errors and errors can have catastrophic consequences.

AND the conditions that require backup power are usually in stressful times like major storms where most humans are more prone to making errors.

 

[ChaseDE]

I totally get that Dave, and I agree with most of you guys, not trying to antagonize at all.

Really though, it is 2 steps and you don't even have to get down and dirty to do them. My workplace is super crazy safety conscious and I never really thought about the repercussions or problems that could arise from backfeeding a house in this way, my dad just showed me and stressed the 2 steps.

I will be more careful from now on for sure, although it is extremely rare I need to do this now that I don't live in the sticks anymore.

 

[Davefr]

I totally get that Dave, and I agree with most of you guys, not trying to antagonize at all.

Really though, it is 2 steps and you don't even have to get down and dirty to do them. My workplace is super crazy safety conscious and I never really thought about the repercussions or problems that could arise from backfeeding a house in this way, my dad just showed me and stressed the 2 steps.

I will be more careful from now on for sure, although it is extremely rare I need to do this now that I don't live in the sticks anymore.

There's actually a few more steps.

3. Ground the generator to earth ground.
4. Turn off all sub breakers so there is no load when starting the generator.
5. Determine which sub breakers you need powered on and ensure these do not exceed the generators capacity. You'll need to take into account any inductive loads like motors that have starting current that can be as high as 10X running current and ensure this does not exceed the surge rating of the generator.
6. Now turn on those individual breakers as long as #5 is OK.

 

[R6 Racer]

Power here goes out 20 or 30 times a year around hear. So often that last month 'Hydro One' (electricity supplier) set up a meeting for the local community too try & explain why & what their doing about it.
What I learnt...
Yes it is illegal, yes it is dangerous IF DONE INCORRECTLY, (also, apparently all people working on power lines are required to treat them as if they were live at all times.)
Almost 80% of the people in attendance back feed.
The cost to have all the proper people & materials come in & install a "proper" switching system can range from $2000.00 to $4000.00. Fore most in attendance that was between 3 & 4 years worth on electrical costs.
The best thing I saw from the meeting was that the general consensus was... If Hydro One does not like back feeding then Hydro One can provide a safe way to protect Hydro One employees. Not one person in attendance felt the need to pay a ridiculous fee in order to create a redundant safety feature for a huge conglomerate that makes billions in profit every year of of many people who need to choose between electricity or food.

In the end Hydro One left saying they liked the idea of putting in a switching option in areas where outages happen this often. Weather anything comes from that... who knows.

To the OP...
you decide, just be safe.
many do it (that's from hydro on) & some do it wrong (which is 1 reason hydro one makes everyone treat all lines as live)


Steve
IMO
A corporation like Hydro One that has the ability to pay lobbyist to entice politicians to slightly change or pass laws, in order for that corp. (HO) to legally steel from its customers, will never get me to pay them more to supposedly protect their employees.

 

[yeldogt]

Power here goes out 20 or 30 times a year around hear. So often that last month 'Hydro One' (electricity supplier) set up a meeting for the local community too try & explain why & what their doing about it.
What I learnt...
Yes it is illegal, yes it is dangerous IF DONE INCORRECTLY, (also, apparently all people working on power lines are required to treat them as if they were live at all times.)
Almost 80% of the people in attendance back feed.
The cost to have all the proper people & materials come in & install a "proper" switching system can range from $2000.00 to $4000.00. Fore most in attendance that was between 3 & 4 years worth on electrical costs.
The best thing I saw from the meeting was that the general consensus was... If Hydro One does not like back feeding then Hydro One can provide a safe way to protect Hydro One employees. Not one person in attendance felt the need to pay a ridiculous fee in order to create a redundant safety feature for a huge conglomerate that makes billions in profit every year of of many people who need to choose between electricity or food.

In the end Hydro One left saying they liked the idea of putting in a switching option in areas where outages happen this often. Weather anything comes from that... who knows.

To the OP...
you decide, just be safe.
many do it (that's from hydro on) & some do it wrong (which is 1 reason hydro one makes everyone treat all lines as live)


Steve
IMO
A corporation like Hydro One that has the ability to pay lobbyist to entice politicians to slightly change or pass laws, in order for that corp. (HO) to legally steel from its customers, will never get me to pay them more to supposedly protect their employees.

Still not logical ... everything is fine until it's not.

 

[Falcon67]

We keep the 6500 ready in the winter - power cords only to the genny if required. With a couple of home made 4 way boxes on the end of some short cords, you can get what you need up and running quick. It's not like the ice cream will melt within seconds of the power going out. We "endured" a 4 hour outage on both Thanksgiving AND Christmas day last year (clear sky, warm, no weather - stupid) without even firing the genny up. And not sure a 6500 has the oomph to finish Thanksgiving dinner in the oven/stove anyway, nor to run the compressor/fan units for the heat pump. Sammiches, space heater or two and electric blankets if needed.

And if I was going to connect a portable genny to a house, I'd drop an appropriate cord out of the panel from a 30A breaker, or install a 30~50A motor base as a minimum to avoid any suicide cords and such. And I'd really, really want a setup where you'd have to physically lock out the main to even engage the genny breaker. Otherwise, cords.

It's just not safe otherwise

 

[tyme2par4]

If you forget to do this, you will, at a minimum be attempting to power the grid at least up to the break in the line.

This is the question I've had. If you did power up the whole block, wouldn't everyone's appliances kicking on trip the breaker on the generator?

 

[txvwnut]

I do it every time I loose power. Is it legal per an NEC code or city code, definitely not. Can it be done, yes it can. When the power goes out the first thing I do is trip the master disconnect so I don't back feed the neighborhood. I have a dedicated plug for the genny that is rated for the max amp output of the genny. Mine is a 5500 watt and it will run pretty much the whole house except the central air and the stove.

 

[WhiffySpark]

3 months ago everyone said this was okay. Now it’s a terrible idea. Make up your mind lol

 

[marinusdees]

It is possible. It is not legal.

 

[75gmck25]

I have a related question, but want to verify that it would work.

If run a 4 wire connection from a 240v breaker in the main panel to a sub-panel in my garage, and then install one of the simple generator interlocks at the main panel (the metal plates that make you to shut off the main before turning on the top 240 volt breaker), would it mean that when main power is off I could slide the interlock plate over, turn on connection to the sub-panel, and feed power from the sub-panel to the main panel. Or is that type of connection prohibited?

Assuming that is allowed, how would I legally and safely connect generator output to the garage sub-panel?

Bruce

 

[exranger06]

I have a related question, but want to verify that it would work.

If run a 4 wire connection from a 240v breaker in the main panel to a sub-panel in my garage, and then install one of the simple generator interlocks at the main panel (the metal plates that make you to shut off the main before turning on the top 240 volt breaker), would it mean that when main power is off I could slide the interlock plate over, turn on connection to the sub-panel, and feed power from the sub-panel to the main panel. Or is that type of connection prohibited?

Assuming that is allowed, how would I legally and safely connect generator output to the garage sub-panel?

Bruce

The easiest way to do that is to not connect the generator directly to the subpanel. Just run the 4 wires from the generator inlet on the garage back to the main panel in the house, and install the interlock kit. Since the subpanel in the garage is connected to the main panel, it will also be energized.

 

[theoldwizard1]

Really though, it is 2 steps ...

Some people can't walk and chew gum !

There is a completely legal, easy but admittedly more expensive solution. In stall a generator interlock in you main breaker with a plug (probably a L14-30P) on the outside of the house. Buy/make an extension cord to run from the generator in the garage to the house. (SOOW 8/4 - around $100 for 50'; you may be able to get bu with SJOW 10/4 which is closer to $1/ft).

 

[grantw]

3 months ago everyone said this was okay. Now it’s a terrible idea. Make up your mind lol

As always, it's the AHJ, adopted NEC code cycle, and any local service providers' rules you need to follow. Places like Florida have stupid LEGAL blocks from you back feeding your house with a generator, interlock or not.

They key point to making a typical generator back-feed safe, is that interlock. It doesn't really matter if you go with an ATS, or a interlock kit. The point is there is a mechanical safety mechanism, that won't allow you to energize the neighborhood power lines when you generator is feeding your house.

If you don't have that interlock, someone will "forget" to isolate the home, and all it takes is that "one time I forgot" to kill someone.

When I upgraded my house to a 200A panel, I included a interlock mechanism just incase I ever need it in the future, and the local inspector signed off on that install.

 

[Eric29]

Assuming that the neutral is bonded to the frame of the generator, when you backfeed, don't you have a situation where a short in a line could potentially carry more current than the line could handle and not trip the breaker because there are two bonded neutrals in the system? Isn't this why it is illegal?

 

[zak77]

Let's just say that myself and numerous neighbors did just that when we lost power last week for a couple days. No one died, there were no injuries, a cat threw up, and the earth kept on turning. It can be done if done right.

 

[tinysparky]

By a $130 mechanical panel lockout to insure the main breaker is off and stays off. Would I do it yes....legal...no....covered by your insurance company if your house burns down....no....but i would still do it

 

[grantw]

By a $130 mechanical panel lockout to insure the main breaker is off and stays off. Would I do it yes....legal...no....covered by your insurance company if your house burns down....no....but i would still do it

Why would a system with an interlock not be legal or covered by insurance?

 

[thickhead]

OP here.

It ***** running power cords through a window and the house to keep the fridge, furnace and a few lights running and listening to the generator ouside my window. If I feed from the garage I can leave the generator running in the garage with an exhaust/muffler extension.

How about if I install a power inlet box off the small panel in the garage, then I would just need a disconnect of some sort at the house main? If you had to do it what would you use?

 

[theoldwizard1]

OP here.
How about if I install a power inlet box off the small panel in the garage, then I would just need a disconnect of some sort at the house main? If you had to do it what would you use?

I already told you how to do it legally and safely !

There is a completely legal, easy but admittedly more expensive solution. Install a generator interlock in you main breaker with a inlet box on the outside of the house. Buy/make an extension cord to run from the generator in the garage to the house. (SOOW 8/4 - around $100 for 50'; you may be able to get bu with SJOW 10/4 which is closer to $1/ft).

The generator interlock feed the power directly into the panel, SAFELY AND LEGALLY !

 

[wyliesdiesels]

3 months ago everyone said this was okay. Now it’s a terrible idea. Make up your mind lol

Everyone?

Who is everyone?

Not on GJ.

The majority collective here has always said feeding a panel with a generator WITHOUT an interlock or transfer switch is not only illegal, but a really bad idea the main being safety.

By a $130 mechanical panel lockout to insure the main breaker is off and stays off. Would I do it yes....legal...no....covered by your insurance company if your house burns down....no....but i would still do it

Mechanical panel lockout?

What are you referring to? A lock on the panel, a lock on the breaker or?

OP here.

It ***** running power cords through a window and the house to keep the fridge, furnace and a few lights running and listening to the generator ouside my window. If I feed from the garage I can leave the generator running in the garage with an exhaust/muffler extension.

How about if I install a power inlet box off the small panel in the garage, then I would just need a disconnect of some sort at the house main? If you had to do it what would you use?

Running power cords through windows is forbidden by the NEC as well.

If you go the power inlet at the garage panel route, you would have no way to feed the house as you would be disconnecting the house panel.

Instead, put in a separate generator feed to the house panel from an inlet at the garage and put an interlock on the main panel with the generator breaker next to the main breaker. This way you can legally feed the house panel, keeping lineman safe and still feed the garage as well if needed.

 

[grantw]

Here is an interlock unit made specifically for my panel. (Siemens)

Siemens-Standby-Power-Interlock-Kit-150-Amps-and-up

This was installed when the AHJ inspector approved the panel and meter.

Legal and UL listed.




Here is the panel with everything else installed. There is no way that the generator feed can back-feed the main as long as that interlock is installed. It's basically enforcing a A/B select for power source, where neither can be on at the same time.

 

[yeldogt]

OP here.

It ***** running power cords through a window and the house to keep the fridge, furnace and a few lights running and listening to the generator ouside my window. If I feed from the garage I can leave the generator running in the garage with an exhaust/muffler extension.

How about if I install a power inlet box off the small panel in the garage, then I would just need a disconnect of some sort at the house main? If you had to do it what would you use?

What's your main panel? some square D panels can take the interlock. They also make a sub panel that comes with the switch and space for 8 circuits -- it not much over 100 bucks. Short feed though the wall to the proper connection box.

You would have to make up the proper extension cord in the length you need

 

[thickhead]

What's your main panel? some square D panels can take the interlock. They also make a sub panel that comes with the switch and space for 8 circuits -- it not much over 100 bucks. Short feed though the wall to the proper connection box.

You would have to make up the proper extension cord in the length you need

I have a GE Powermark Gold main panel. Top left breaker is the 60 amp that feeds out to the garage. If I have a breaker added to the top right I can use an interlock and feed it through the outside wall to a connection box. Then an extension cord to the generator at the garage.

 

[larry4406]

Following along with interest.

As I understand the debate:

As the detached garage is a sub panel off the house main panel, its feeding breaker would not be involved with an interlock otherwise the detached garage is not normally energized while on the grid.

To have the generator co-located at the detached garage, then as Old Wizard said, a separate 4-wire generator feed circuit from the detached garage back to the main panel would be needed and this breaker would then be interlocked to the main breaker.

Thus there would be two sets of 4-wire feeds run to the detached garage; one for normal grid power to the garage from the house and the other for generator power from garage back to the house. Is it ok to have to/from feeds from a detached structure?

I think the OP is trying to do both grid and generator feed off the single set of 4-wire feeds which is something I would also like to do. Is there any way to do this that is Code compliant with a single set of 4-wire feeds to the detached garage sub-panel?

 

[thickhead]

...I think the OP is trying to do both grid and generator feed off the single set of 4-wire feeds which is something I would also like to do. Is there any way to do this that is Code compliant with a single set of 4-wire feeds to the detached garage sub-panel?

Larry,
I started this thread to get informed and its working for me. The male/male cord I was going to make is a STUPID idea and I hadn’t thought that one through. Definitely learned a few things so far, but I hope like you there is a good way to use the 4-wire feed I already have.

 

[Ole Slewfoot]

30-50A twist lock cords avoid suicide plugs.

 

[thickhead]

Can I have a 2nd 60 amp breaker in my main panel connected to the same 4-wire feed but locked off with a disconnect and add a power inlet port in the garage?

 

[Alchymist]

And then there is the question of neutral/frame bonding at the generator. Always something overlooked. People will do what people will do, regardless of the advice to do it right.