Checking for 3 phase power

Reply

  #1  
Old 05-20-15, 01:41 PM
Member
Thread Starter
Join Date: May 2015
Location: United States
Posts: 4
Checking for 3 phase power

Hello, I am about to be leasing a building for my business and need to determine if 3 phase power is available. Is this as simple as taking a multimeter to an electrical panel and checking across the different lines and the neutral? Thanks in advance!
 
Sponsored Links
  #2  
Old 05-20-15, 01:54 PM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
You can just look at the breakers in the panel(s). No need to open the panel, nor would it be appropriate to do so without proper PPE. If the large breakers have three handles tied together or take up three spaces then it's a three phase panel. If the large breakers take up only two slots, it's a single phase panel. All panels in a commercial setting should also be labeled on the front cover indicating voltage, amperage, phase and source.

You may want to have an electrician check out the building to make sure it is actually compatible with the equipment you need to operate. Even if your building does have three phase, there are many different common configurations that may or may not work with your equipment. You would also want to evaluate if the existing three phase service has sufficient capacity to power the equipment.

Hiring an electrician in advance to spec out the design will be the best couple hundred bucks you ever spend. For reference, see this horror story of someone who built out their shop without checking the electrical: http://www.doityourself.com/forum/el...wer-boost.html
 

Last edited by ibpooks; 05-20-15 at 02:15 PM.
  #3  
Old 05-20-15, 02:38 PM
Member
Join Date: Nov 2012
Location: USA
Posts: 3,132
Why not just call the POCO and ask them what what the service is ? phases ,voltages,amperage.
Also hiring an electrician to check it to see if it matches your requirements as ibpooks suggested.
Geo
 
  #4  
Old 05-20-15, 03:37 PM
Member
Join Date: Oct 2014
Posts: 516
If you open the panel and you have 3 or 4 pole breaker then you have 3phase wiring. If the things those breakers are connected to work, you have 3 phase power. If you want to know if three phase power is available, you should need to call the utility.
 
  #5  
Old 05-20-15, 07:53 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,508
What is a 4 pole breaker ?

Ben has the best advice. More than likely if you aren't the property owner the power company won't help you.
 
  #6  
Old 05-21-15, 04:22 AM
Member
Join Date: Mar 2010
Location: USA
Posts: 2,860
A 4 pole panel top breaker can cut the neutral, as may be desired for some building solar panel installations or backup generators

Not to be confused with a double wide quad tandem breaker which may or may not have handles 1 and 4 tied together and handles 2 and 3 tied together for use with 120/240 volt or 120/208 volt multiwire branch circuits. (A 3 phase 120/208 volt system and panel can originate MWBCs with 3 hots plus neutral.)
 

Last edited by AllanJ; 05-21-15 at 04:41 AM.
  #7  
Old 05-21-15, 06:21 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,990
Just looking for a multi-pole main breaker is not a reliable way to determine if a service is 3 phase or not. I have seen many 200 amp breakers that look like 4 breakers ganged together but really are only for single phase. Also in commercial spaces many panels are main lug only without mains.

One other thing to watch for is a 3 phase delta service. This is a high leg service where the B phase is 208 to ground. While this is not a deal breaker, it can limit you if you have a lot of 120 volt loads. It can also cause issues on any 3 phase equipment that requires equal potential from each hot to ground. I have ran into this on a lot of printing equipment.

Easiest ways to tell is look at the panel labels, ask the building owner, or hire an electrician.
 
  #8  
Old 05-21-15, 07:35 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,674
Not mentioned yet is a 4-wire drop.
 
  #9  
Old 05-21-15, 08:05 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
The biggest problem with looking at the drop or the power company side is that commercial services are often quite a bit different than residential. There might be three phase at or near the building complex central utility area, but that doesn't necessarily mean it makes it to each tenant space. For example the building or complex might get 480V three phase in from the power company, which powers a central distribution panel in the complex for the parking lot lights, shared HVAC equipment, and then each tenant space gets a single phase 208/120V submetered service fed from a transformer powered by the main. In this case, the building owner is often responsible for owning and maintaining the transformers. The building technically has three phase, but it might be a $50k job to extend it to one of the tenant spaces. You just can't tell without looking at that stuff on site.
 
  #10  
Old 05-21-15, 08:20 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,674
I should have worded that differently. Is the drop two insusated wires and a bare messenger?
 
  #11  
Old 05-21-15, 09:38 AM
Member
Thread Starter
Join Date: May 2015
Location: United States
Posts: 4
Thank you all for your responses. I would have hired an electrician, but 1) this seems pretty trivial to have to call an electrician, and more importantly 2) this is a DIY forum!

I did look at your responses and looked at he breaker panel and figured out it is 3 phase. I'll post some pics shortly to verify.

Your inputs have been priceless! Thanks, once again!
 
  #12  
Old 05-21-15, 09:56 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,990
The only reason I suggested hiring an electrician is in the commercial world you can not legally make any modifications to the electrical system in most areas anyway so it might be a good idea to fine one you like/trust.

It is good you have it figured out. The next questions you should be asking is, is there enough capacity (amps) to run the equipment for your business, and what is the voltage of the service? If it is a 480 volt service it could get expensive adding transformers.
 
  #13  
Old 05-21-15, 10:22 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
In all the states I know of three phase work requires a licensed electrician, so it is somewhat out of scope for the DIY topic. I don't have a problem giving some advice or things to look for, but the job itself is beyond DIY. Many three phase panels you should not even remove the cover without an energy calculation and arc flash PPE. The safety issues are much greater. Make sure to follow up with Mr. Ironhand's questions about the characteristics of the service.
 
  #14  
Old 05-21-15, 10:35 AM
Member
Thread Starter
Join Date: May 2015
Location: United States
Posts: 4
Here are the pictures. Sorry, I didn't know how to rotate them!

Name:  IMG_0012.jpg
Views: 182
Size:  25.2 KB

Name:  IMG_0013.jpg
Views: 185
Size:  34.9 KB

Name:  IMG_0014.jpg
Views: 184
Size:  19.0 KB

Name:  IMG_0015.jpg
Views: 177
Size:  20.6 KB

Name:  IMG15.jpg
Views: 175
Size:  15.1 KB
 

Last edited by ray2047; 05-21-15 at 10:57 AM. Reason: Rotate images and adjust images.
  #15  
Old 05-21-15, 10:39 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,674
You need to use a program like IRFan View (free) to rotate your images. I have done it for you and cropped and/or enlarged some using IRFan View
 
  #16  
Old 05-21-15, 12:11 PM
Member
Thread Starter
Join Date: May 2015
Location: United States
Posts: 4
Thanks, Ray! ..............................................
 
  #17  
Old 05-21-15, 12:29 PM
Shadeladie's Avatar
Super Moderator
Join Date: Jan 2005
Location: USA
Posts: 3,835
this is a DIY forum!
True, but meant for the average homeowner, not for commercial or business purposes.
 
  #18  
Old 05-21-15, 01:36 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,990
That is a 3 phase Cuttler Hammer CH panel. It appears to be 200 amps based on the breaker and the size of the pipe on the bottom, but there could a different sized breaker/fuse ahead of this one.

I can't tell on the sub panel, could be either way.
 
  #19  
Old 05-21-15, 01:54 PM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
I would also hazard a guess that this is a 208Y120 panel given the 240V main breaker and the mixture of single, double and triple pole breakers, but that is a guess.
 
  #20  
Old 05-21-15, 03:48 PM
Member
Join Date: Oct 2014
Posts: 516
I almost forgot how bland US / Canadian panels are at first glance.

You should pull the cover of thee sub panel and see what color wires you have coming in from the main panel.

Do three phase panels use open buses as well?
 
  #21  
Old 05-21-15, 04:09 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,990
Three phase load centers are pretty much the same as what you find in residential. Panel boards are similar with the exception of the use of bolt in breakers.

Wire colors may not be helpful due to the fact there is no color requirements except for neutrals, grounds, and a high leg. However trade standards are black/red/blue for 120/208Y, Brown/orange/yellow for 277/480Y. 120/240 Delta will have the B phase marked orange.
 
  #22  
Old 05-21-15, 05:13 PM
Member
Join Date: Oct 2014
Posts: 516
I guess what I was getting at is that split phase residential panels usually have interlocking buses so to speak so you can have a 240v breaker touching both hots. I was just trying to imagine what the 3 way zig zag would look like.

One thing's for sure when (or if) I'm back in the US I'll miss my DIN rail panels.

For the OP though, it's pretty clear that you've got 3ph power. You probably could have just looked at your electric meter too.
 
Reply

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


Thread Tools
Search this Thread
Display Modes
'