Wdan432
I have a 300amp service riser on a residential job feeding through one meter to 2 seperate 150amp main breaker panels in basement. Homeowner does not want to protect entire house- just essential circuits. With the loads I have calculated, I should be able to get away witha 17KW unit. Question is what kind of set up should I use? I dont want to have to use a 400amp service rated ATS on exterior. I would like to install transfer switch next to 2 150amp panels and install seperate subpanel for essential circuits. The problem is how would I feed Utility into transfer switch without needin a service rated switch? ANY GUIDANCE ON THIS WOULD BE MUCH APPRECIATED!
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yucan2
Wdan432;7954 wrote:
I have a 300amp service riser on a residential job feeding through one meter to 2 seperate 150amp main breaker panels in basement. Homeowner does not want to protect entire house- just essential circuits. With the loads I have calculated, I should be able to get away witha 17KW unit. Question is what kind of set up should I use? I dont want to have to use a 400amp service rated ATS on exterior. I would like to install transfer switch next to 2 150amp panels and install seperate subpanel for essential circuits. The problem is how would I feed Utility into transfer switch without needin a service rated switch? ANY GUIDANCE ON THIS WOULD BE MUCH APPRECIATED!


If you purchase the 17kw packaged unit it comes with a ATS that has 16 circuit capacity with no main. Simply feed it from a 2 pole 65 if you can find one or a 2 pole 60, which is readily available, from either of the 150 amp panels and drag over the circuits you want to protect.

Since yours is not a whole house solution a service rated transfer switch is not required nor will you receive one with the 17kw pre-packaged unit.
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Wdan432
thanks leroy

What if the main breaker goes on the panel I feed from instead utility loss and other panel still has utility? Will that matter?
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Wdan432
Also I have 2 ac condensors to feed with 50amp breakers.
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Wdan432
Can you load shed with that ATS?
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yucan2
Wdan432;7957 wrote:
What if the main breaker goes on the panel I feed from instead utility loss and other panel still has utility? Will that matter?


Yes that will matter. The system will only sense voltage loss from the panel with the 2 pole breaker installed. However, it is highly unlikely that you would ever lose power from the utility to one panel and not the other.
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ceb58
Wdan432;7957 wrote:
What if the main breaker goes on the panel I feed from instead utility loss and other panel still has utility? Will that matter?


With the ATS Leroy is talking about it would not matter. You circt. that you want are fed from the branch circt. breakers in the ATS.

Wdan432;7958 wrote:
Also I have 2 ac condensers to feed with 50amp breakers.


This may be the problem with a 17kw. Also using the ATS you feed it with a 60amp breaker depending on the size of the A/C's and other loads you may have a problem under normal circumstances.

Wdan432;7959 wrote:
Can you load shed with that ATS?


I THINK you can buy the load shed ct's separately and install but still doesn't address the load under normal.
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yucan2
Wdan432;7958 wrote:
Also I have 2 ac condensors to feed with 50amp breakers.


Check the LRA on those units. A 17kw may struggle to start either of those.
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yucan2
Ceb is correct, it doesn't matter that power loss to one panel only is monitored as all the critical circuits are in the ATS. To clarify, if power is loss to the panel that [U]is not[/U] monitored, the generator will not start and no transfer will take place. There is no need, as the panel that is being monitored is still supplying power to the 2 pole breaker that feeds the ATS, that houses the critical circuits.

As for your load shed question, as stated, you really need to look at your load calcs first to determine if load shedding will even help. While that switch does not have load shed capability, there are available components to provide this.

If going with a 20KW is an option, I would seriously consider it.
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ceb58
yucan2;7963 wrote:
Ceb is correct, it doesn't matter that power loss to one panel only is monitored as all the critical circuits are in the ATS.



Its the season, we are agreeing again :D :D :D
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yucan2
ceb58;7964 wrote:
Its the season, we are agreeing again :D :D :D


Yeah, I'm going to have to work on that. :D

BTW, Wdan, if your or the owners budget will allow for a 20kW, don't go with, as in, do not buy the 20kW pre-packaged unit. Purchase the 20kW standalone. The ATS that comes with the 20kW pre-packaged unit will not help you. Go with the same ATS that comes with the 17kW pre-packaged unit and you're good to go.
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ohmslaw
Can you install (1) rtsd 150 amp switch and load shed the A/C?
Then you could drag all the essential circuits to one panel.
Tim

PS :I agree with Yucan and CEB.
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Wdan432
Uereka- That's a good idea!

I can definately talk customer into 20Kw. Without load shedding though, I just cant handle both AC condensors? This 150 amp load shedding ATS option seems feasable though. I could just take feedfrom meter out of one of the panels and feed into ATS. Then backfeed existing panel from ATS and make IT the new subpanel. I can take out of this panel non-essential circuits and bring into it circuits I will need from other panel. Am I missing something or is this the best way to go being that now I will be able to load shed both AC condensors from new Load Shed ATS moun ted next to existing panels.
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ohmslaw
That is how I would do it.
Tim
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ceb58
Wdan432;7970 wrote:
I can definately talk customer into 20Kw. Without load shedding though, I just cant handle both AC condensors? This 150 amp load shedding ATS option seems feasable though. I could just take feedfrom meter out of one of the panels and feed into ATS. Then backfeed existing panel from ATS and make IT the new subpanel. I can take out of this panel non-essential circuits and bring into it circuits I will need from other panel. Am I missing something or is this the best way to go being that now I will be able to load shed both AC condensors from new Load Shed ATS moun ted next to existing panels.


That would be the best. However you will need to install a SE rated OCP/disconnect before the ATS for the utility side. And a SE rated disconnect for the gen. load. Then the panel that will be for the back up circts. will become a sub panel. The neutrials and EGC will need to be seperated in the panel.
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Wdan432
Why cant...

Why cant I just install the new 150amp service rated disconnect next to 1 of the panels? 2) In Jersey, you do not need disconnect at Generator. Thank all of you for your input. I was kind of stuck and you all helped me out alot. As I grow my Generator side of my business, I am thankful for people like yourselves being willing to donate your time and knowledge to this forum. It really is a blessing! Merry Christmas to all!
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ceb58
Wdan432;7975 wrote:
Why cant I just install the new 150amp service rated disconnect next to 1 of the panels? 2) In Jersey, you do not need disconnect at Generator. Thank all of you for your input. I was kind of stuck and you all helped me out alot. As I grow my Generator side of my business, I am thankful for people like yourselves being willing to donate your time and knowledge to this forum. It really is a blessing! Merry Christmas to all!


Then you are fine. You did not indicate that the ATS was SE rated thus my comment on the disconnects. Nor that you were in Jersey.

But I must ask why did New Jersey amend code to not require a disconnect for the Gen.?
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yucan2
ceb58;7977 wrote:
Then you are fine. You did not indicate that the ATS was SE rated thus my comment on the disconnects. Nor that you were in Jersey.

But I must ask why did New Jersey amend code to not require a disconnect for the Gen.?


I told them too :D
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ohmslaw
I guess I should have been more detailed. The RTSD is a SE rated switch.
Tim
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ceb58
ceb58;7977 wrote:


But I must ask why did New Jersey amend code to not require a disconnect for the Gen.?


yucan2;7979 wrote:
I told them too :D


OH, the power you have. :eek:

ohmslaw;7980 wrote:
I guess I should have been more detailed. The RTSD is a SE rated switch.
Tim


That's cool. But I am still curious as to why NJ doesn't require a disconnect for the gen.
Trying to get a answer over on MH's site from the Jersey guys.
Here in NC the inspectors have come to a consensus that the breaker on the gen. doesn't comply with 445.18,225.36,225.31 and 225.32 (2008)
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ohmslaw
We never install a GEN disconnect. We always get a passing grade.
With the breaker accessible externally of the cabinet it is even easier to get approval.
Tim
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Wdan432
disconnect

My thoughts exactly OhmsLaw. Why wouldn't the 2pole breaker on exterior of cabinet count as disconnect? Its totally accessible and meets NEC requirements.
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ceb58
ohmslaw;7983 wrote:
We never install a GEN disconnect. We always get a passing grade.
With the breaker accessible externally of the cabinet it is even easier to get approval.
Tim


Wdan432;7984 wrote:
My thoughts exactly OhmsLaw. Why wouldn't the 2pole breaker on exterior of cabinet count as disconnect? Its totally accessible and meets NEC requirements.


OK, Now I am speaking of requirements in the 2008 NEC, someone BORROWED my 2005. And the code requirements that inspectors look for on gen. installs where I am. And their points on inspections.
I have been told by a New Jersey elect. that NJ UCC has not amended 445.18
With that said the breaker on the gen., unless special ordered, dose not comply with 445.18. Then we go to 702.11 that states the disconnect SHALL meet the requirements of 225.36. The breaker on the gen. doesn't comply with 225.36. 225.36 then refers you to 225.31.

So the bottom line is they do not allow the breaker on the gen. to serve as the disconnecting means, unless the gen. has been ordered with a SE rated breaker and is with in sight.

With all that if the inspectors are not requiring you to install the disconnect then so be it. Its just if one day you get turned down on an inspection for the disconnect it is because the other inspectors have not been enforcing the code.
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ohmslaw
My opinion is the Inspectors are using common sense .
Tim
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ceb58
ohmslaw;7986 wrote:
My opinion is the Inspectors are using common sense .
Tim


Well we agree to disagree. The inspectors are not using common sense. They are like many they have been bombarded with these installs and have not completely grasped the many code sections that apply to a gen. install.
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