ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Lock-down Thread
by Bill Addiss - 02/27/21 01:16 PM
Northern Tool Recalls Powerhorse Generators
by Admin - 02/25/21 09:49 PM
You will never guess
by gfretwell - 02/25/21 07:48 PM
New tool
by SMOKEYBOB - 02/15/21 04:59 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 14 guests, and 19 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
3 Phase Power (490 volts on a 480 volt system) #168225 08/29/07 04:48 PM
Joined: Sep 2003
Posts: 35
A
acetoday Offline OP
Member
Help,

I'm a residential electrician and don't work much with 3 phase power. My question is on a 3 phase 480 volt system is it abnormal to read 490 volts? I have a ac unit rated for 460 volts (nominal voltage) however as stated we are reading 490 volts at the unit. Is this a reason to be concerned? I should mention there are 3 other units on the roof also rated 460 volts and are operating normal.

Any feedback would be greatly appreciated.....

Work Gear for Electricians and the Trades
Re: 3 Phase Power (490 volts on a 480 volt system) [Re: acetoday] #168226 08/29/07 05:05 PM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
It's very likely a 480 volt supply system and 490 volts is not that bad.

The AC unit is labeled 460 but is designed to work on 480 volt supply system.

They do not make Motors actually labeled 480 volts.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: 3 Phase Power (490 volts on a 480 volt system) [Re: iwire] #168228 08/29/07 05:09 PM
Joined: Feb 2003
Posts: 939
F
frenchelectrican Offline
Member
Also most power supply system are useally ± 10% range so with the 480 system you got a bit leeway with it so few voltage over the system is not bad at all

Merci , Marc


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)

Re: 3 Phase Power (490 volts on a 480 volt system) [Re: frenchelectrican] #168229 08/29/07 05:57 PM
Joined: Aug 2007
Posts: 853
L
leland Offline
Member
"leeway" thats a good thing.
N-Star here, has been running "questionably" low lately.

That makes you worry.

You have a fine stable voltage, no worries.

Re: 3 Phase Power (490 volts on a 480 volt system) [Re: leland] #168230 08/29/07 06:15 PM
Joined: Sep 2003
Posts: 35
A
acetoday Offline OP
Member
Leland, frenchele,and iwire,

Thank you for all your responses. It's greatly appreciated. I didn't think it was a problem, but I have a customer and his A/C mechanic is advising him not to run his unit. I feel bad for the customer because he's at a loss for what to to do.

Thanks again!!!!

Re: 3 Phase Power (490 volts on a 480 volt system) [Re: acetoday] #168232 08/29/07 06:39 PM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
Originally Posted by acetoday
I have a customer and his A/C mechanic is advising him not to run his unit.


Click on the link for a pdf you can print out with a lot of official information to teach the A/C mechanic, maybe you will print out two and give him one.

Air Conditioning Equipment Voltage Ranges

Basically a 460 tagged unit is designed to run from 432 to 508 volts.

Last edited by iwire; 08/29/07 06:45 PM.

Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: 3 Phase Power (490 volts on a 480 volt system) [Re: iwire] #168234 08/29/07 06:42 PM
Joined: Aug 2007
Posts: 853
L
leland Offline
Member
3- one for the customer to rest their worried mind.

Re: 3 Phase Power (490 volts on a 480 volt system) [Re: leland] #168241 08/29/07 09:50 PM
Joined: Jul 2004
Posts: 9,569
G
gfretwell Offline
Member
Bob said

"Basically a 460 tagged unit is designed to run from 432 to 508 volts."

That is news you can use. I was trying to do the math in my head from the earlier 10% post and I got "brain feeeze" like when you eat ice cream on a hot day.


Greg Fretwell
Re: 3 Phase Power (490 volts on a 480 volt system) [Re: iwire] #168242 08/29/07 09:52 PM
Joined: Sep 2003
Posts: 35
A
acetoday Offline OP
Member
Bob,

Thanks again for being so helpful. I printed out the document and filed it away. It was of great use to me as well as the ac mechanic. Thank you again for reaching out.

Respectfully,
Bob Hanifin
Owner, ACE Electric

Re: 3 Phase Power (490 volts on a 480 volt system) [Re: acetoday] #168255 08/30/07 04:25 AM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
Originally Posted by acetoday
Bob,

Thanks again for being so helpful.


Glad I could help, I would like to say I have all this knowledge in my head......but really I am just a good 'Googler'. wink


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Page 1 of 2 1 2

Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
AllClear
AllClear
Belmond Iowa US
Posts: 44
Joined: August 2005
Show All Member Profiles 
Top Posters(30 Days)
MCosta 3
Popular Topics(Views)
275,453 Are you busy
209,361 Re: Forum
196,636 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3