4 pole ATS advantage?

Status
Not open for further replies.
chris kennedy

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
I got another ATS install today. 800Amp 480V.

What is the point of switching the grounded conductor? Does this effect a UPS that loses its EGC for the brief time it takes to transfer? I've had no problems, just wondering.
 
chris kennedy said:
What is the point of switching the grounded conductor?
Click to expand...

There is likely other reasons but one that I know of is when you have GFP protection of services or feeders.

If you don't switch the neutral you can fool the GFP protection into a false trip. It might not ever happen but it can. It all depends on the loading and setting of the GFP.
 
iwire said:
There is likely other reasons but one that I know of is when you have GFP protection of services or feeders.

If you don't switch the neutral you can fool the GFP protection into a false trip. It might not ever happen but it can. It all depends on the loading and setting of the GFP.
Click to expand...


Yes sir I fully understand that. This is 800 Amp no GFP. (I should add the the ATS was not speced either 3 or 4 pole by the EE.)
 
chris kennedy said:
Yes sir I fully understand that. This is 800 Amp no GFP. (I should add the the ATS was not speced either 3 or 4 pole by the EE.)
Click to expand...

Then I can not think of any good reason to go four wire, but that does not mean there isn't. :smile:
 
Wherever possible, go three wire, as then the ground stays solid. Even if you have a four pole ATS, you dont need to use all four poles. The only reason to switch neutrals is becuase the circuit arrangement forces you so to do.
 
The only real other reason is if the neutral/EGC bond at the service disco and/or the generator can't be separated.
 
dbuckley said:
Even if you have a four pole ATS, you dont need to use all four poles.
Click to expand...

That depends on the ATS, some may be able to be programed to work without the neutral but many will sense the missing neutral as a problem resulting in a transfer to emergency.
 
iwire said:
That depends on the ATS, some may be able to be programed to work without the neutral but many will sense the missing neutral as a problem resulting in a transfer to emergency.
Click to expand...

This is correct but the ATS will also sense no EM neutral available resulting in no transfer.

I deal with Lake Shore and Kohler. Both programable. When I add the 4th pole to my other ATS I will let you know the cost of the tech.
 
iwire said:
...the missing neutral as a problem...
Click to expand...

Good point. But... the 'missing' neutral(s) may be able to be 'replaced' with nothing more than a bit of #10...

Modern ATSs are getting too damned clever :) Time was when only the really top end gear (like Cyberex static switches) would notice such things...
 
dbuckley said:
Modern ATSs are getting too damned clever :)
Click to expand...

Each one I get seems to require an hour or two of reading and research. Then a go back for some adjustments after the bldg. is fully occupied.
 
Status
Not open for further replies.
Top