Wdan432
I have been requested to provide a 20KW air cooled NG unit to power a 2 family home with 2 seperate 100amp meters coming off a 200amp service lateral. I am assuming I can provide back-up power to both units with 1 20KW unit considering the loads I have calculated. My questions come in on how to install transfer for both units simultanously. If I use 2 seperate 100amp ATS's and install them on exterior on the sides of meters, do I parallel feeder from generator from one ATS to the other and are the lugs in ATS's rated for two wires under each from Generator? Second question and more critical is do I only monitor utility voltage from 1 switch or both and do I just bridge connections for transfer circuit inside generator housing so that both switches transfer simultanously under utility power loss? Anybody have experience with this, your advise and expertise would be much appreciated. This Forum ROCKS!
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Gman1
[url]http://www.polarisconnectors.com/black.html[/url]

Use these from gen and install in first switch, then from polaris to lugs in first switch, then from polaris to second switch. You can not double lug, illegal and not possible if using the right size wire as lugs are too small. All control wires on one switch, then jump 23/194 to switch 2.
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Wdan432
I take it you have done this before by your quick response. Much appreciated! What about T1 from transfer switch? I just had an issue with a 20Kw unit with nexus controller where it was not in install manual to run and connect T1 so I didn't and the battery drained 2 weeks later and Generator would not crank. I called Generac and they told me they new of the problem but had not yet posted a Bulletin to installers.
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Wdan432
Obviously, N1 and N2 only need to come from 1 ATS, correct?
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yucan2
Wdan432;7670 wrote:
Obviously, N1 and N2 only need to come from 1 ATS, correct?


That's true and therein lies the rub.

If you're monitoring the utility voltage which is what it sounds like, why not go with one a 200 amp service rated ATS directly after the 200 amp disconnect or better yet replace the existing 200 amp disconnect altogether?

In your setup, if the ATS that has the N1 and N2 sensing conductors terminated loses power for whatever reason, failure, non-payment, etc. the generator will start. Not good.

The only reason the genny should ever start is when both premises lose power from the utility.

This is all predicated on the premise that your 20kw unit is capable of carrying the full available load during a transfer. No AC in these dwellings? Be careful.

A picture of the existing electrical service would be quite helpful.
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ceb58
Wdan432;7667 wrote:
I have been requested to provide a 20KW air cooled NG unit to power a 2 family home with 2 seperate 100amp meters coming off a 200amp service lateral. I am assuming I can provide back-up power to both units with 1 20KW unit considering the loads I have calculated. My questions come in on how to install transfer for both units simultanously. If I use 2 seperate 100amp ATS's and install them on exterior on the sides of meters, do I parallel feeder from generator from one ATS to the other and are the lugs in ATS's rated for two wires under each from Generator? Second question and more critical is do I only monitor utility voltage from 1 switch or both and do I just bridge connections for transfer circuit inside generator housing so that both switches transfer simultanously under utility power loss? Anybody have experience with this, your advise and expertise would be much appreciated. This Forum ROCKS!


Since you are assuming so will I. I assume there are service disconnects that you can come out of to supply utility power to the ATS's. Since you will need to set a gen. disconnect why not just get one with parallel lugs to feed each ATS.
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Gman1
Wdan432;7670 wrote:
Obviously, N1 and N2 only need to come from 1 ATS, correct?

Correct.

As mentioned, if you need a disconnect from the gen to the switch (We don't) you could get one with double lugs (or add them) on the load side.
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Wdan432
No disconnect at Generator is required in NJ. However, it just got more complicated. Off a 2 gang 200amp meter base I have 1- 150amp panel for 1st floor and 1- 50amp disconnect feeding to second floor apartment. Generac has a new 150amp ATS as I just found out but with wire size I need from Gen. to 1st transfer switch- lugs in second transfer are not big enough being that I would only be using 100 amp ATS for existing second floor 50amp feeder. Also, I will now need a 27Kw Liquid Cooled unit.
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bronco
Use a 200 amp service entrance rated switch after the main 200 amp meter this powers up everything no need for 2 ats's
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yucan2
bronco;7693 wrote:
Use a 200 amp service entrance rated switch after the main 200 amp meter this powers up everything no need for 2 ats's


This would have been my recommendation as well, problem is, that according to the OP, there does not appear to be a 200 amp main meter but rather (2) individual meters. Though the meter sockets themselves may be rated for 200amps, there is still a dilemma.

As much as I'd like to, I am unable to wrap my head around just (1) ATS.

Secondly, in the above recommendation, even if there were a 200 amp main meter, the customer would continue to be charged by the utility even while on generator power as the gen load would be traveling thru the secondary meters.

See attached drawing for some additional clarity.
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bronco
you are right.

Pick one ats as the master run n1 and n2 from it to the unit. 23 and 194/15B from both ats to unit. done. You should use service entance rated ats though.
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Wdan432
That was my issue. I have 2 seperately metered services coming into building (1-150amp- 1- 50amp). Size of wire from 27kw Generator will fir under lugs in 150amp ATS but not sure it will in 100amp ATS. This is my dilemma. I know I need 2 seperate ATS, dont think they need to be service rated as I have main breakers in garage directly on the other side of the wall where meters are. What to do?
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Skip Douglas SkipD
Wdan432;7710 wrote:
That was my issue. I have 2 seperately metered services coming into building (1-150amp- 1- 50amp). Size of wire from 27kw Generator will fir under lugs in 150amp ATS but not sure it will in 100amp ATS. This is my dilemma. I know I need 2 seperate ATS, dont think they need to be service rated as I have main breakers in garage directly on the other side of the wall where meters are. What to do?
Simply use two 200-amp service-rated ATS panels. The price difference is not great from the lower current rated units.
Skip Douglas
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ohmslaw
Can you put a load center into the apartment @ the panel?
Then connect the 150 amp switch to the first floor.
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ceb58
Wdan432;7710 wrote:
That was my issue. I have 2 seperately metered services coming into building (1-150amp- 1- 50amp). Size of wire from 27kw Generator will fir under lugs in 150amp ATS but not sure it will in 100amp ATS. This is my dilemma. I know I need 2 seperate ATS, dont think they need to be service rated as I have main breakers in garage directly on the other side of the wall where meters are. What to do?


I think you are going to have trouble with 230.70 A 1. With the disconnects being inside and setting the transfer switch out side. How/what wireing methods are used from meter to inside disconnects? How/what wireing method is used from the inside disconnects to the panels?
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