Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 08-28-2011, 03:44 PM   #1
Newbie
 
Join Date: Aug 2011
Posts: 16
Share |
Default

3 phase panels and sub panels


just bought a house that a doctor had put in an xray machine and had three phase power brought in. its a 100 year old house and some of the changes over the years are terrifying. im gut renovating from top floor down. i am creating 2 apartments on top floor and will live on lower three floors.
there are currently 2 main panels both fed from same meter with 250 wire 3 hots and a nuetral one has a integral main 200 breaker / cut off the other a seperate switch with three 200 fuses at first i thought the second panel might be a sub because it was not diurectly grounded but realized it grounds through the other panel and it is definitely fed directly from service.
i want to install new panels for each of these apartments the run would be less than 100' want to do it in a way that for now they are sub panels but eventually they would be converted to their own meters. i think utility will not let me mix 3 and 2 phase service and ive come to apreciate the 3 phase advantages and would like to pass that advantage on to apartments that may get central air of panels. intend to run #2 wire from 3pole breakers rated 100 amps -150amps depending on panels i find 3ph panels turn out to be expensive however i do heavy construction [hvac] and often come across 200 amp 3 phase 240v panels being taken out of service two i could have now have 200 amp main cut off breaker could i simply replace that breaker these panels are quite large for my purpose but the panels would each cost $600 without the 40 breakers. i understand when those panels become mains they must have shut offs in reach so those main breaker style helps. understand about bonding difference between subs and mains and 3 phase load balance but really im a novice think i will need to run 3 hots and nuetral and ground

michael825 is offline   Reply With Quote
Old 08-28-2011, 03:52 PM   #2
Licensed electrician
 
Join Date: Sep 2007
Location: Maryland
Posts: 7,397
Default

3 phase panels and sub panels


Before going any further you need to find out if the power company will even supply 3 phase to your unit again. What is the voltage of the 3 phase?

__________________
Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
Jim Port is online now   Reply With Quote
Old 08-28-2011, 04:00 PM   #3
Newbie
 
Join Date: Aug 2011
Posts: 16
Default

3 phase panels and sub panels


when i say the un grounded second main panel is grounded through the other panel its because the service wires come through a race where they are divided with a splice before they go into each panel so it seems the nuetral is "grounding" the second one to the first which has a green ground going to earth. i admit im a bit hazy on 3 phase ground vs nuetral and on second thought i dont think i would need a fifth ground wire up to apartment panels but must only tie their nuetral into the nuetral bar of main i sub them from and later wnen they are disconected to get ther own meters ide have a problem lol or since i thought to use #2 bx could that serve as panel ground i doubt it but its probably cheaper to run a separate smaller ground then
michael825 is offline   Reply With Quote
Old 08-28-2011, 04:03 PM   #4
Newbie
 
Join Date: Aug 2011
Posts: 16
Default

3 phase panels and sub panels


i would have thought they would not be supplying again so much as splicing in a couple new meters i have this system already running now and 3 hot legs 225 amp #250 service wire is more than sufficient for 3 separate domestic panels no?
michael825 is offline   Reply With Quote
Old 08-28-2011, 04:10 PM   #5
Newbie
 
Join Date: Aug 2011
Posts: 16
Default

3 phase panels and sub panels


its 120 240 v
michael825 is offline   Reply With Quote
Old 08-28-2011, 07:01 PM   #6
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,361
Default

3 phase panels and sub panels


Are you SURE you have 120/240 and not 208Y/120?

There is a big difference in how sub-panels would be connected ....
__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Old 08-28-2011, 09:19 PM   #7
Newbie
 
Join Date: Aug 2011
Posts: 16
Default

3 phase panels and sub panels


yes all poles are 120 and when scrounging for panels at work ive stayed away from 208 though i wasnt sure how much it would matter in a panel rating
michael825 is offline   Reply With Quote
Old 08-28-2011, 09:21 PM   #8
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,361
Default

3 phase panels and sub panels


IF all poles are 120 as you have stated, then your three phase service is 208Y/120 Volts.

You do NOT have any 240 Volts available.

Have you used a digital meter to confirm your phase-to-phase voltage?
__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Old 08-28-2011, 09:22 PM   #9
Newbie
 
Join Date: Aug 2011
Posts: 16
Default

3 phase panels and sub panels


its kind of why i want to keep it seems only upside more efficient more power in same amperage more power int house more versatile im already pulling 3 phase for tools and expect the ac will be three p[ole
michael825 is offline   Reply With Quote
Old 08-28-2011, 09:22 PM   #10
I=E/R
 
a7ecorsair's Avatar
 
Join Date: May 2010
Location: Minnesota
Posts: 2,052
Default

3 phase panels and sub panels


Quote:
Originally Posted by michael825 View Post
yes all poles are 120 and when scrounging for panels at work ive stayed away from 208 though i wasnt sure how much it would matter in a panel rating
You didn't answer the question completely. What do you read for voltage pole to pole? This should be three separate readings.
A to B
A to C
B to C
a7ecorsair is offline   Reply With Quote
Old 08-28-2011, 09:25 PM   #11
Newbie
 
Join Date: Aug 2011
Posts: 16
Default

3 phase panels and sub panels


hmm i did a while back but can not be certain except the meter and panels all say 120/240 which i assumed meant 120 per leg i have pulled 220 of a 2 pole breaker
michael825 is offline   Reply With Quote
Old 08-28-2011, 09:29 PM   #12
Newbie
 
Join Date: Aug 2011
Posts: 16
Default

3 phase panels and sub panels


multi meter was stolen i will have to get back on that
michael825 is offline   Reply With Quote
Old 08-29-2011, 07:01 AM   #13
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,361
Default

3 phase panels and sub panels


Quote:
Originally Posted by michael825 View Post
hmm i did a while back but can not be certain except the meter and panels all say 120/240 which i assumed meant 120 per leg i have pulled 220 of a 2 pole breaker

In the US there is no such thing as "220" -- either you have 208 or 240 available.

You can have 208 volts on a panel rated for 120/240. The nameplate rating is the maximum that the panel can safely handle. It is not verification of your available system voltage.
__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Old 08-29-2011, 07:44 AM   #14
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,861
Default

3 phase panels and sub panels


If you measure 220 between two hot legs and 110 volts between hot and neutral, then this is a 120/240 system and not a 208 volt system.
__________________
Stop wasting time re-adjusting the pattern. Have several lawn sprinklers, one for each pattern.
AllanJ is offline   Reply With Quote
Old 08-29-2011, 03:29 PM   #15
Newbie
 
Join Date: Aug 2011
Posts: 16
Default

3 phase panels and sub panels


ok got a meter so i want reading from two hot legs,every combination of hot legs and also each leg to nuetra if its 208 to determine which is the high leg?l

michael825 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.