80kw kohler gen for 400 amp residential service

[roger]

Now she'll need to invest in a portable load bank.

 

[tortuga]

Can't all ATSs be manually overridden to be started, stopped, and/or kept off?

The problem I run into is homeowners don't usually buy a 80kW generator instead they get some hot deal on 14kw with a 200 Amp ATS included and want it installed on the entire 320A service.
This is always with no EMS/Load management, and they if don't meet 702.4(A)(2)(a) then I need a 702.4(A)(2)(b) EMS.
Furthermore the 2023 code tightened 702.4(A)(2)(b) up. What used to pass (and they still sell) as "load shed" system may no-longer qualify as a listed "Energy management System".

 

[qcroanoke]

Can't all ATSs be manually overridden to be started, stopped, and/or kept off?

Yes. But the problem with shutting it down under load is starting it back up under load and if it's big enough load the generator may not like that. You would almost want the ATS to go to neutral on shutdown

 

[suemarkp]

What is her service, a 400A panel or two 200's side by side? How about two 200A manual transfer switches if she has two 200A panels? These are so much more common that two of them may be cheaper than a 400A single unit. If the loads are divided decently across the panels, it could make fuel saving even easier by not switching on one of the panels if less critical things are on one of them.

 

[AC\DC]

With this being so oversized, she might have problems with the driver "wet-stacking" due to not enough load. Bigger is not always better.

This one’s one of my concerns. I don’t know what wet stacking is. Is that the proper term so o can google.

 

[kwired]

Seems if they want to save fuel they should have gone with a smaller unit. JMO.
That diesel motor is probably like 75ish horsepower at a minimum.

It still going to suck down the fuel when it is running even if not loaded much. Plus diesel won't store all that long compared to LP or NG but you will want a pretty good supply of it should you have a longer term outage situation.

Do they even have enough "essential" load in the house to load this thing beyond 25% of it's capacity? Load shedding of bigger loads lets you use smaller generator and still be able to run those bigger loads when there isn't much other loading.

 

[kwired]

This one’s one of my concerns. I don’t know what wet stacking is. Is that the proper term so o can google.

Diesel not running with enough load can run below it's designed running temperature, can lead to unburned fuel and soot passing on through and into the exhaust system. Will reduce efficiency (even more) and likely will shorten life of the engine as well.

 

[AC\DC]

This one’s one of my concerns. I don’t know what wet stacking is. Is that the proper term so o can google.

Found link on wet stacking.

 

[hillbilly1]

Yes. But the problem with shutting it down under load is starting it back up under load and if it's big enough load the generator may not like that. You would almost want the ATS to go to neutral on shutdown

That’s a problem too, a lot of automatic transfer switches do not have a neutral position, especially that size.

 

[Birken Vogt]

Yes. But the problem with shutting it down under load is starting it back up under load and if it's big enough load the generator may not like that. You would almost want the ATS to go to neutral on shutdown

That is the job of a "programmed transition" switch, just add money and stir.

This one’s one of my concerns. I don’t know what wet stacking is. Is that the proper term so o can google.

Yes it is a proper term and it is the bane of diesel generators everywhere.

Seems if they want to save fuel they should have gone with a smaller unit. JMO.
That diesel motor is probably like 75ish horsepower at a minimum.

It still going to suck down the fuel when it is running even if not loaded much. Plus diesel won't store all that long compared to LP or NG but you will want a pretty good supply of it should you have a longer term outage situation.

Do they even have enough "essential" load in the house to load this thing beyond 25% of it's capacity? Load shedding of bigger loads lets you use smaller generator and still be able to run those bigger loads when there isn't much other loading.

Welcome to the world of generators where people get what they think they want, and then tell you to make it work.

If she really wants a diesel for the end of the world, 13-20 kw with a large fuel tank will be a better choice with a mechanical engine that anybody can work on instead of a high tech computer diesel. And use a proper load mgt system.

But good luck convincing anybody of any of this.

 

[AC\DC]

I get what you guy say about what she should get. But they unloaded it off the semi before they called me it’s sitting there waiting for me.

 

[hbiss]

Did she give any explanation for getting such an oversized generator? Bigger= more fuel consumption= less run time= end of her world happens sooner.

-Hal

 

[AC\DC]

Did she give any explanation for getting such an oversized generator? Bigger= more fuel consumption= less run time= end of her world happens sooner.

-Hal

She filthy rich, she bought online. probably was asked what size service she has and then they gave her 334 Amp gen. This is her lake house they don't even use it only 3 months out of the year.....

 

[shortcircuit2]

Dooms-Dayer in my neck of the woods did 3-20KW generators that fed different parts of the property. Each had switch to bring them on as needed to conserve fuel. Also setup with pin and sleeve to manually use a working genset if another died. 6-1000 gallon propane tanks buried in the yard. Also had solar and battery backup. Room in the lower level with 6-months of food and all necessary survival gear.

 

[kwired]

That’s a problem too, a lot of automatic transfer switches do not have a neutral position, especially that size.

But AFAIK they usually do not automatically transfer to the standby source until there is voltage sensed from that source.

 

[hillbilly1]

But AFAIK they usually do not automatically transfer to the standby source until there is voltage sensed from that source.

The bigger ones have a “go to neutral” position, and can be programmed to have a time delay for large loads to come to a stop before transferring. The op’s problem is it will not transfer back to utility if both sources are dead. Easiest way is to turn off the generator output breaker before restarting.

 

[kwired]

The bigger ones have a “go to neutral” position, and can be programmed to have a time delay for large loads to come to a stop before transferring. The op’s problem is it will not transfer back to utility if both sources are dead. Easiest way is to turn off the generator output breaker before restarting.

OP's client basically wants a manual transfer switch, so that is likely what I would get them.

People that buy such an oversized unit for a second home, then don't want to use the standard ATS for it to "save on fuel" kind of makes no sense.

If they were simply misinformed or suckered into buying the large unit maybe suggest they don't install it and instead sell it and get something more suitable for their needs.

 

[Birken Vogt]

The bigger ones have a “go to neutral” position, and can be programmed to have a time delay for large loads to come to a stop before transferring. The op’s problem is it will not transfer back to utility if both sources are dead. Easiest way is to turn off the generator output breaker before restarting.

A programmed transition switch will go back to neutral even if utility is not present. Check before you buy though. You would have to make up some kind of sequencing to send the switch back to neutral before shutting the genset down.

If they were simply misinformed or suckered into buying the large unit maybe suggest they don't install it and instead sell it and get something more suitable for their needs.

That may be the best idea.

 

[roger]

Or it might be worth looking into a Diesel to LP conversion. No, I don't know if it's even possible for the engine we're talking about but when dealing with a rich, clueless, won't know how to exercise or maintain the unit, and will be calling you every time it faults you'll be glad if it can be

 

[ATSman]

But AFAIK they usually do not automatically transfer to the standby source until there is voltage sensed from that source.

Roger, that is correct because the golden rule is an ats will not transfer to a dead bus (source), unless, in the case of Zeniths, the Load Shed option will allow it to transfer to either neutral or utility source depending on 2 or 3 position ats design, when shedding the load.