Generator for home without a transfer switch

[Atlantis]

That’s a hack to make a generator designed to be used as a job site generator with ground fault protection work to backfeed a house panel. Neutral and ground can only be bonded at one spot.

This is not a separately derived system issue, this is a portable generator being hooked up in a single-family dwelling. In a single-family dwelling when you start separating your grounded from your grounding u are Temting fate for some very serious hazards.

Let’s be clear, I am not, and I have never heard anyone advocating having ZERO neutral-ground bonds in a residential system. So now that we agree on that...

You can install a generator with a neutral-chassis/ground bond, or you can install one that is unbonded and relies on the bond at the main panel. My understanding is there are exactly zero code compliant installations that have both.

I was under the impression that for some reason code MANDATES that standby generators are installed as separately derived systems, and that installed it with a 3 pole transfer switch, non SDS was not to code.

Clearly I am wrong. What I am hearing is that you often install 3 pole transfer switches, non SDS, with a generator that does not have a chassis/ground-neutral bond.

Am I missing anything else?

To safely emulate your tried and true methods, it sounds like I would want to not have the neutral/ground bond on the generator, not connect the house ground to the generator ground, and DO ground the generator chassis with a good grounding rod.

Or is literally the only difference just making sure that the neutral isn’t bonded to the generator chassis, but you still connect the ground from the receptacle to the chassis? Grounding rod is just extra protection at that point?

 

[Asaltweapon]

Take that money and do it right with an interlock.

NOT if your little Honda 2000 and the boiler are the only thing you care about.
Built it and installed from off the shelf parts by a local licensed sparky.

 

[Knuckle Dragger]

Get a Generlink: Transfer Switch | Global Power Products

Mine is on order, there was a 11 week backlog when I ordered it. I should have it at the end of February. It's relativity inexpensive and easy for an electrician to install once the power company cuts the power and pulls the meter. The big advantage over a transfer switch is that you can power ANY circuit, but not necessairly ALL circuits at the same time.

 

[RHJJ]

NOT if your little Honda 2000 and the boiler are the only thing you care about.
Built it and installed from off the shelf parts by a local licensed sparky.

For you fine, the o. p. stated he needs more than heat. For what he would pay for that, he would be better paying more and gets what he wants without extension cords. Running extension cords in a blizzard sucks.

 

[sfd10]

Have a licensed Electrician install a transfer switch. Don't do Suicide Wiring. I've seen it burn.

 

[arsco]

one thing I would like to do is run a small inverter gen for just the furnace and a few lights for over nights and keep the big one for the well, shit pump day loads, lot less fuel

 

[Varmint]

That's nice. I was only pointing out to the OP that a newer appliance/furnace might not operate off his portable generator.

Why is that?

 

[DPR]

Why is that?

Clean / Dirty Power with Furnace

Hello - new to the forum, but need some advice. Just went through a major power outage in the metro-Detroit area. I'll make a very long story as short as I can. The new high efficiency Lennox furnaces will not run off "standard" generator power. Lennox is saying generator power is too dirty...

www.electriciantalk.com

 

[RHJJ]

Why is that?

Most modern appliances have mother boards and most portable generators make dirty power and they can take them out. My samsung refrigerator motherboard died in 3 times in 10 years and I am thinking the generator might have been guilty.

 

[SgtHal75]

Let’s be clear, I am not, and I have never heard anyone advocating having ZERO neutral-ground bonds in a residential system. So now that we agree on that...

You can install a generator with a neutral-chassis/ground bond, or you can install one that is unbonded and relies on the bond at the main panel. My understanding is there are exactly zero code compliant installations that have both.

I was under the impression that for some reason code MANDATES that standby generators are installed as separately derived systems, and that installed it with a 3 pole transfer switch, non SDS was not to code.

Clearly I am wrong. What I am hearing is that you often install 3 pole transfer switches, non SDS, with a generator that does not have a chassis/ground-neutral bond.

Am I missing anything else?

To safely emulate your tried and true methods, it sounds like I would want to not have the neutral/ground bond on the generator, not connect the house ground to the generator ground, and DO ground the generator chassis with a good grounding rod.

Or is literally the only difference just making sure that the neutral isn’t bonded to the generator chassis, but you still connect the ground from the receptacle to the chassis? Grounding rod is just extra protection at that point?

Are we still talking about a portable generator installation? Done properly with a cord and plug disconnecting means and a typical 10 circuit manual transfer switch?...Are you talking about a fixed stand by whole house/building generator installation?

 

[gbest]

Interlock kit is the way to go.

 

[Atlantis]

Are we still talking about a portable generator installation? Done properly with a cord and plug disconnecting means and a typical 10 circuit manual transfer switch?...Are you talking about a fixed stand by whole house/building generator installation?

My takeaway from this thread is that code does not specify which type of generator/installation you have to install at a residential location. Only HOW to install a SDS VS non SDS.

So really we are talking about both.

I think OP is clearly talking about a portable generator installation. In that situation you’re saying it’s generally installed as a NON SDS? So you would not want the chassis/neutral bond at the generator. You install a 3 pole transfer switch I’m guessing? What about the grounds? Do you tie the ground from the panel to chassis? Do you add a ground rod at the generator as well?

Perhaps someone takes their 10Kw portable generator and sets it on a pad and puts it in a dog house and doesn’t plan on it being all that portable. Now it’s closer to a fixed stand by. Do you generally installed those as an SDS with a 4 pole transfer? Probably something automatic?

 

[xjma99]

My takeaway from this thread is that code does not specify which type of generator/installation you have to install at a residential location. Only HOW to install a SDS VS non SDS.

So really we are talking about both.

I think OP is clearly talking about a portable generator installation. In that situation you’re saying it’s generally installed as a NON SDS? So you would not want the chassis/neutral bond at the generator. You install a 3 pole transfer switch I’m guessing? What about the grounds? Do you tie the ground from the panel to chassis? Do you add a ground rod at the generator as well?

Perhaps someone takes their 10Kw portable generator and sets it on a pad and puts it in a dog house and doesn’t plan on it being all that portable. Now it’s closer to a fixed stand by. Do you generally installed those as an SDS with a 4 pole transfer? Probably something automatic?

No. Separately derived systems have nothing to do with a residential backup generators!!

try having ground and neutral bonded in two places with a generator that has ground fault protection on the output. Some have gfi on the L14-30!!

 

[Varmint]

Clean / Dirty Power with Furnace

Hello - new to the forum, but need some advice. Just went through a major power outage in the metro-Detroit area. I'll make a very long story as short as I can. The new high efficiency Lennox furnaces will not run off "standard" generator power. Lennox is saying generator power is too dirty...

www.electriciantalk.com

Oh, cause they're computerized maybe? Thanks, the one I just got is an inverter type.

 

[Atlantis]

No. Separately derived systems have nothing to do with a residential backup generators!!

try having ground and neutral bonded in two places with a generator that has ground fault protection on the output. Some have gfi on the L14-30!!

So you are not ALLOWED to install a generator as a separately derived system in a residential setting? Or it’s just pointless and uncommon?

So when YOU install a generator, and that generator does not have a chassis/neutral bond because code says it shall not, what do YOU do with the ground conductors?

 

[SgtHal75]

My takeaway from this thread is that code does not specify which type of generator/installation you have to install at a residential location. Only HOW to install a SDS VS non SDS.

So really we are talking about both.

I think OP is clearly talking about a portable generator installation. In that situation you’re saying it’s generally installed as a NON SDS? So you would not want the chassis/neutral bond at the generator. You install a 3 pole transfer switch I’m guessing? What about the grounds? Do you tie the ground from the panel to chassis? Do you add a ground rod at the generator as well?

Perhaps someone takes their 10Kw portable generator and sets it on a pad and puts it in a dog house and doesn’t plan on it being all that portable. Now it’s closer to a fixed stand by. Do you generally installed those as an SDS with a 4 pole transfer? Probably something automatic?

Why 3 pole in a house? There are no services for single family dwelling units that have 3 phase power, 3 poles. Your grounded conductor is not a pole.

For a portable generator Installation you would simply use a cord and plug disconnect means and a manual transfer switch. This is probably the most common out there.

Now a generator for a commercial building is a whole different kettle of fish. You have many electrical and building codes that come into play depending on how many stories the building is. I think you are overthinking what a SDS is.

 

[SgtHal75]

So you are not ALLOWED to install a generator as a separately derived system in a residential setting? Or it’s just pointless and uncommon?

So when YOU install a generator, and that generator does not have a chassis/neutral bond because code says it shall not, what do YOU do with the ground conductors?

How would a generator not have a chassis? I’m a little confused. Could you please tell me where in the NEC or Mass amendments it says a generator SHALL not have a chassis? I’m not being a dick, just looking for clarification.

Ive installed many Generators from 30 story buildings to 3 stool barbershops and I’ve never seen a generator without a chassis.

 

[Atlantis]

How would a generator not have a chassis? I’m a little confused. Could you please tell me where in the NEC or Mass amendments it says a generator SHALL not have a chassis? I’m not being a dick, just looking for clarification.

Ive installed many Generators from 30 story buildings to 3 stool barbershops and I’ve never seen a generator without a chassis.

Yeah I guess that wasn’t clear...? “Chassis/neutral bond” was intended to mean a bond between neutral and the chassis (ground) at the generator.

Why 3 pole in a house? There are no services for single family dwelling units that have 3 phase power, 3 poles. Your grounded conductor is not a pole.

For a portable generator Installation you would simply use a cord and plug disconnect means and a manual transfer switch. This is probably the most common out there.

Now a generator for a commercial building is a whole different kettle of fish. You have many electrical and building codes that come into play depending on how many stories the building is. I think you are overthinking what a SDS is.

So you only switch the hots, and the neutral is always connected? What about the ground? Same thing?

 

[SgtHal75]

Yeah I guess that wasn’t clear...? “Chassis/neutral bond” was intended to mean a bond between neutral and the chassis (ground) at the generator.

Ok, when you say ground or grounded that’s really neutral, depending on who you talk to. Grounding is basicslly your green earth ground, hence grounding electrode or grounding conductor. U can’t split this bond at the Generator and simply say it’s a SDS. I don’t have the code in front of me but I will look it up tomorrow and post an update.

 

[SgtHal75]

Yeah I guess that wasn’t clear...? “Chassis/neutral bond” was intended to mean a bond between neutral and the chassis (ground) at the generator.



So you only switch the hots, and the neutral is always connected? What about the ground? Same thing?

Nuetral is basically common. Once again neutral is your ground or grounded (white) conductor and your return path. Your green grounding is your protection for anything going wrong like a dead short. U will know if u throw voltage on it, trust me.

 

[Atlantis]

Nuetral is basically common. Once again neutral is your ground or grounded (white) conductor and your return path. Your green grounding is your protection for anything going wrong like a dead short. U will know if u throw voltage on it, trust me.

Yep. So when you install a portable generator. The transfer switch is switching the hots, and you are directly wiring the neutral from the generator to the house neutral and grounding conductor from the generator to the grounding conductor from the house? Neither of those are being switched?

If so then none of those generators could have the neutral bonded to the grounding conductor or chassis at the generator, no?

 

[dcmdon]

Go bigger, you only get about 80% of the rating with propane. Since gens shouldn’t be loaded over 80% of their rating anyways , except for brief periods, you are looking at 80% of 80%.
Also you don’t need a transfer switch. If you have a spare 30Amp breaker you can tie into it and back feed your panel through a 30Amp twist lock installed on the outside of the house. Transfer switches are easier but the method I mentioned isn’t bad either. You just have to be conscious about opening the main before turning on the spare ties into the gen. Otherwise you will need a break gen

This is illegal and unsafe unless you know what you are doing.

I'm not saying it shouldn't be done, but it isn't idiotproof.

If you start the generator and close the breaker tying it into the panel, but fail to turn off the main, your house will backfeed the grid. This can
1) overload your generator and make it's breaker continuously trip.
2) kill a line man by energizing the wire he is working on that is supposed to be dead.

The interlock that someone mentioned above is a brilliant solution. It essentially does not allow you to switch the breaker for the generator on until the main breaker is off.

I have done this several times and set up several friends this way when we were without power for 6 days after hurricane Irene.

In the interest of safety, I actually removed the main breaker from my friends' panels. It makes it pretty much idiotproof.

 

[Coyote33]

Most modern appliances have mother boards and most portable generators make dirty power and they can take them out. My samsung refrigerator motherboard died in 3 times in 10 years and I am thinking the generator might have been guilty.

Then don't buy that junk. Insist on a solid system that can take the fluctuations. They don't build 'em like they used to.

 

[Executive]

Jesus.

See NEC 702.11, 702.12, and 445.20.
For that matter, also see NEC 250.22, 250.24, 250.25, and 230.85 (yeah, 230.85 makes a difference)

While not the worst, this is easily in the bottom five of the many, many, many NES "Generator Threads" I have seen over the last fifteen-plus years. Some of the statements here are beyond ridiculous and outright dangerous.

EDIT: Right after typing this post I saw this gem: "In the interest of safety, I actually removed the main breaker from my friends' panels. It makes it pretty much idiotproof." My God...

People have no concept of some of the terms being tossed around here: separately derived system, grounded vs. grounding, neutral...

There are way too many variables for an armchair electrician to deal with. Do yourselves a favor and look up "Generator Threads" here. Then call Palladin.

Chris

 

[Rob Boudrie]

EDIT: Right after typing this post I saw this gem: "In the interest of safety, I actually removed the main breaker from my friends' panels. It makes it pretty much idiotproof." My God...

Thanks for the post. I was too busy scratching my head trying to figure out "WTF is he talking about?".

 

[rscalzo]

In the process of replacing my 8kw Generac with one around 15kw. Not that the smaller one didn't run the essentials but the larger one will run everything at a lower percentage of output.

 

[Robin Proctor]

This is illegal and unsafe unless you know what you are doing.

I'm not saying it shouldn't be done, but it isn't idiotproof.

If you start the generator and close the breaker tying it into the panel, but fail to turn off the main, your house will backfeed the grid. This can
1) overload your generator and make it's breaker continuously trip.
2) kill a line man by energizing the wire he is working on that is supposed to be dead.

The interlock that someone mentioned above is a brilliant solution. It essentially does not allow you to switch the breaker for the generator on until the main breaker is off.

I have done this several times and set up several friends this way when we were without power for 6 days after hurricane Irene.

In the interest of safety, I actually removed the main breaker from my friends' panels. It makes it pretty much idiotproof.

it’s not illegal. It’s against code if you are a liscenced electrician and yes you should have an interlock which is more for your safety than anyone else’s.... But It certainly will not kill a lineman. People throw this line out because they have heard others says it and they hear it and believe it. It’s not true though your radio flyer home gen will have its field collapse before it is ever able to do this.

 

[mikelawtown]

NOT if your little Honda 2000 and the boiler are the only thing you care about.
Built it and installed from off the shelf parts by a local licensed sparky.

Had Paladin install this just for boiler
It’s a backup for just heat if needed

 

[SgtHal75]

This is illegal and unsafe unless you know what you are doing.

I'm not saying it shouldn't be done, but it isn't idiotproof.

If you start the generator and close the breaker tying it into the panel, but fail to turn off the main, your house will backfeed the grid. This can
1) overload your generator and make it's breaker continuously trip.
2) kill a line man by energizing the wire he is working on that is supposed to be dead.

The interlock that someone mentioned above is a brilliant solution. It essentially does not allow you to switch the breaker for the generator on until the main breaker is off.

I have done this several times and set up several friends this way when we were without power for 6 days after hurricane Irene.

In the interest of safety, I actually removed the main breaker from my friends' panels. It makes it pretty much idiotproof.

Yup, happens all the time

 

[SgtHal75]

Yep. So when you install a portable generator. The transfer switch is switching the hots, and you are directly wiring the neutral from the generator to the house neutral and grounding conductor from the generator to the grounding conductor from the house? Neither of those are being switched?

If so then none of those generators could have the neutral bonded to the grounding conductor or chassis at the generator, no?

Yes. But isn’t that what you were calling an SDS?.... because it’s not.