generator question

[westelectric]

Generator is Generac 20 kw.. I believe the generator has an 80 amp cb in it.. Run #4's 100 amp ATS. Install emergency sub panel next to main panel with a load no more than 80% of 80 amps. ATS not switching neutral than no ground rod required. Is this typical. What about disco outside the gen? Separate pipe for control wiring. If control wiring is low volt. then do I need a 3rd pipe for 120volt circuit for batt charger?. Any way to protect the whole house (200amp main panel) by locking out a/c condensers and elec oven and staying code compliant? Thanks in advance for comments.

 

[iwire]

Generator is Generac 20 kw.. I believe the generator has an 80 amp cb in it.. Run #4's 100 amp ATS.

Sounds good

Install emergency sub panel next to main panel with a load no more than 80% of 80 amps.

It can be loaded up to 100% for non-continuous loads.

Not many loads in a home are truly continuous per the NEC.

But there is nothing wrong with leaving some room.

ATS not switching neutral than no ground rod required. Is this typical.

Yes that is right.

What about disco outside the gen?

Yes you need one 445.18

Separate pipe for control wiring. If control wiring is low volt.

If the control wiring is low volt per the NEC it may or may not require a separate pipe, but most generator instructions specify a separate pipe.

then do I need a 3rd pipe for 120volt circuit for batt charger?.

You can run that with the feeder.

Any way to protect the whole house (200amp main panel) by locking out a/c condensers and elec oven and staying code compliant? Thanks in advance for comments.

IMO the only way would be to have an interlock set up with the ATS that would shut down the AC condensers and oven.

The HVAC equipment would be easy, just break their control circuits with aux contacts on the ATS. You would likely need to install a ice cube relay to do this.

The oven would be more of a problem as you need to break 240 volt at 50 amps. If you could get a plug in 50 amp shunt trip breaker that would be the least cost but would need manual reseting.

 

[peter d]

The oven would be more of a problem as you need to break 240 volt at 50 amps. If you could get a plug in 50 amp shunt trip breaker that would be the least cost but would need manual reseting.

We had to do an stove shutdown for an elderly customer with alzheimers for the home care people to shut off the stove after they leave. We used an inexpensive contactor from Grainger and a "hoffman" box. Might be more cost effective to do it that way than a shunt trip.

 

[iwire]

We used an inexpensive contactor from Grainger and a "hoffman" box. Might be more cost effective to do it that way than a shunt trip.

Normally the shunt is cheaper then a contactor, however considering in this case the breaker is already purchased you might find a 50 amp contactor for not to much.

 

[westelectric]

what if I did a load calc. for the whole house and it comes in under 80amps including ac's. would I have to lock them out ? I heard something about a power master that would prevent both ac's from running at the same time.

 

[iwire]

what if I did a load calc. for the whole house and it comes in under 80amps including ac's. would I have to lock them out ? I heard something about a power master that would prevent both ac's from running at the same time.

As long as you can show the NEC calculated load is less then 20 KW (about 83 amps) you are good to go.

I have never seen the power master but that could do it assuming it was automatically triggered by the ATS. (Unless it always alternates the equipment)

 

[LarryFine]

If the control wiring is low volt per the NEC it may or may not require a separate pipe, but most generator instructions specify a separate pipe.

That's one that's always bothered me. The flex from the genny to the terminal box contains all of the wires, but we shouldn't continue that? :-?

Besides, that 4-conductor cable contains two conductors with 240v between them, and two at 12v. It's obviously insulated for the higher voltage. :roll:



Okay, thanks. I feel better now.

 

[stickboy1375]

That's one that's always bothered me. The flex from the genny to the terminal box contains all of the wires, but we shouldn't continue that? :-?

Besides, that 4-conductor cable contains two conductors with 240v between them, and two at 12v. It's obviously insulated for the higher voltage. :roll:



Okay, thanks. I feel better now.

I hear ya LArry, never understood this one myself... and oh yeah, Generac's require aground rod per directions...

 

[LarryFine]

I hear ya LArry, never understood this one myself... and oh yeah, Generac's require aground rod per directions...

I actually don't mind that one so much. With the Bosch rotary ahmmer, it takes less than a minute to drive a 1/2" cu rod, and the rod is part of the invoice.


Hunt Stevenson: "Is it just me or do you hate the way your shorts feel when they're wet?"
Kazihiro: "Actually I kind of like it." ~ Michael Keaton and Gedde Watanabe in Gung Ho

 

[iwire]

I actually don't mind that one so much. With the Bosch rotary hammer, it takes less than a minute to drive a 1/2" cu rod,

Come up and try that in New Rockland .... err I mean New England. :grin:

Unless your using a real demo hammer it can still take a long time.

 

[stickboy1375]

Come up and try that in New Rockland .... err I mean New England. :grin:

Unless your using a real demo hammer it can still take a long time.

Yep... New England is not fun to do any type of digging, The soil is pretty much rocks with a little bit of dirt in between....

 

[cadpoint]

64 amps are left! I don't think thats what U meant!

Generator is Generac 20 kw.......Run #4's 100 amp ATS. Install emergency sub panel next to main panel with a load no more than 80% of 80 amps.

Use as said a Stunt trip or contactors to seperate conduit.

Modern day heat pumps are always on, but the reset/ demand button could be anywhere.

The whole house aspect is more a AHJ issue.

For me, its more a comfort and Food Issue thing, I think I'd do other.

It always gets me that heaters and A/C are isolated in a no power situation.
With all things considered ...

 

[wirebender]

Generac's require aground rod per directions...

The instructions on the Generac I am about to install say to use a ground rod if required by code.

 

[stickboy1375]

The instructions on the Generac I am about to install say to use a ground rod if required by code.

cool... I'll have to check next time I install one, maybe they changed.

 

[hillbilly1]

The ground rod connects to the lug on the outside frame of the generator, do not connect it to the neutral. Generac does run the control voltage and charger power together, which is legal as long as the wire is rated for the highest voltage available. Kohler on the other hand, will not warrant the generator if the controls and the charger power or block heater are run together. Seperate conduit required.

 

[LarryFine]

The instructions on the Generac I am about to install say to use a ground rod if required by code.

My county says the same thing about spacing the unit from the house: Follow the manufacturer's instructions. Naturally, the instructions say to go by the local jurisdiction's requirements.

So, since there were no back-panel openings on this one, I set the unit about 8" from the house, because the customer wanted it tucked in behind the bushes and as hidden from the street as possible.

 

[cadpoint]

The ground rod connects to the lug on the outside frame of the generator, do not connect it to the neutral. Generac does run the control voltage and charger power together, which is legal as long as the wire is rated for the highest voltage available. Kohler on the other hand, will not warrant the generator if the controls and the charger power or block heater are run together. Seperate conduit required.

No, Well maybe ... Yes ... Insulation is the Key word here ...

300.3(C)(1) 600 volts, Nominal, or Less ...

a/c - d/c shall be premitted to occupy the same equipment wiring enclosures, cable, raceway.
All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within ....

 

[dnem]

ATS not switching neutral than no ground rod required. Is this typical. What about disco outside the gen?

Transfer switch does not transfer/switch the neutral which means it's not a SDS and the neutral must be isolated from ground inside the generator, but how does this impact the ground rod situation ? . 250.50 establishes the ground rod [or other electrode] requirement. . "structure served" must have an electrode. . It has nothing to do with the ATS or if the gen is categorized as a SDS.

I agree that "structure served" is somewhat ambiguous.

"What about disco outside the gen?"
Doesn't the generator have a breaker on it ? . This would be the disconnect and also wouldn't the existance of a disconnect on the gen push it toward being a "structure served".

Compare this to a pool.
Example #1, aboveground pool and motor is plugged into a one gang weatherproof box mounted to a pipe or peice of strut sticking out of the ground. . Ground rod at the plug box required ? . Most people would say it's not a "structure served".
Example #2, inground pool and motor is powered from a freestanding pedastal mounted subpanel that contains a couple of breakers. . Ground rod at the subpanel pedestal required ? . Many people would say it is a "structure served".

So is the generator, that has a breaker in it, like the pedestal subpanel. . They're both feed with a feeder. . Aren't they both a "structure served" ?

I have an even better question.

Why does 250.50 say "structure served" and not "structure supplied" ? . Does served mean a service ? . Does 250.50 apply to a second building supplied by a feeder from a first building ? . Or does the electrode requirement for the second building only come from the wording found in 250.32 ? . The second building does not have to be considered to be a "structure served" in order for 250.32 to apply.

Is there any ROP, ROC wording that addresses "structure served" for a building that is supplied by a feeder or branch circuit(s) ?

 

[dnem]

On second thought, everybody ignore this part

Why does 250.50 say "structure served" and not "structure supplied" ? . Does served mean a service ? . Does 250.50 apply to a second building supplied by a feeder from a first building ? . Or does the electrode requirement for the second building only come from the wording found in 250.32 ? . The second building does not have to be considered to be a "structure served" in order for 250.32 to apply.

Is there any ROP, ROC wording that addresses "structure served" for a building that is supplied by a feeder or branch circuit(s) ?

I'm going to put it on a separate thread.

 

[iwire]

David the generator may well be a structure but it is not normally served or supplied by a feeder. The feeder serves or supplies another building or structure which will need a GEC.

The generator may be served with a branch circuit for the batt charger and or block heater.