3 Phase 240 To 1 Phase (208ish) - Electrical - DIY Chatroom Home Improvement Forum
Advertisement


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

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

Reply
 
Thread Tools
Display Modes
Old 09-23-2010, 12:20 PM   #1
Newbie
 
Join Date: Sep 2010
Posts: 6
Rewards Points: 10
Default

3 phase 240 to 1 phase (208ish)


I have an old tool and die shop. It has 3 phase service. There is a bus with fused boxes across the ceiling. Each is hooked up to a line with the 3 hot wires (each fused) and one bare ground to the box itself. I would like to run single phase 220 (208) out of one of the boxes. If I hook up 2 of the poles (leaving one empty) with my red and black wire and ground my white and green to the box... is that safe/correct? This is how the old owner of the shop has this hooked up for one of the boxes already but not sure how much I trust that. He is not using the ground (green) just the 2 hot and neutral (white) which is grounded to the box.

There is 110 plugs thoughout the shop. I'm assuming using one leg and a neutral?

-Mike
berrmich is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 09-23-2010, 12:35 PM   #2
nap
You talking to me?
 
nap's Avatar
 
Join Date: Dec 2007
Location: sw mi
Posts: 7,551
Rewards Points: 6,290
Default


at the service, you need to take a voltage reading from each phase to every other phase.

then, you need to take a voltage reading from each phase to ground

then, each phase to neutral.



report the findings

then, is there only 3 bus bars in the bus?

If so, there is no neutral so you cannot connect anything that requires a neutral to that bus.


Quote:
and ground my white and green to the box... is that safe/correct?
absolutely not. A single phase 240 does not have a neutral anyway.
nap is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 09-23-2010, 12:48 PM   #3
" Euro " electrician
 
frenchelectrican's Avatar
 
Join Date: Apr 2006
Location: WI & France { in France for now }
Posts: 5,369
Rewards Points: 2,000
Default


I am on the same page as Nap is however there is one more gotcha on the buss drop points.

The fuse boxes on the buss drop are sized some are at 30 and some are 60 and few case larger so it depending on how big the load you want to hook up it may have to change the buss drop box size or order new one that will be not cheap by the way.

Normally this useally done by electrician to deal with it.

Merci.
Marc
frenchelectrican is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 09-23-2010, 01:32 PM   #4
Newbie
 
Join Date: Sep 2010
Posts: 6
Rewards Points: 10
Default


I was told that they are 60's. Should be plenty for what I'm doing. It is for a car lift. The instructions (I don't have the lift yet.. comes tomorrow) say I need 12/4 SO wire. So I assumed that I needed the neutral. So from what I understand you only need to have a neutral if you are running 110. I'm wondering if there is something on the lift that requires 110 so as to actually need all 4 wires. What other reason to require 4 wires?

So if it just needs 220 and I don't need a neutral this should be easy. Run 2 hots off the box and ground the green to the box? (After checking to make sure there is not a "wild" hot.)
berrmich is offline   Reply With Quote
Old 09-23-2010, 01:34 PM   #5
Newbie
 
Join Date: Sep 2010
Posts: 6
Rewards Points: 10
Default


oops.. and yes only the 3 bars. No neutral in the box.

-Mike
berrmich is offline   Reply With Quote
Old 09-23-2010, 01:43 PM   #6
" Euro " electrician
 
frenchelectrican's Avatar
 
Join Date: Apr 2006
Location: WI & France { in France for now }
Posts: 5,369
Rewards Points: 2,000
Default


Quote:
Originally Posted by berrmich View Post
I was told that they are 60's. Should be plenty for what I'm doing. It is for a car lift. The instructions (I don't have the lift yet.. comes tomorrow) say I need 12/4 SO wire. So I assumed that I needed the neutral. So from what I understand you only need to have a neutral if you are running 110. I'm wondering if there is something on the lift that requires 110 so as to actually need all 4 wires. What other reason to require 4 wires?

So if it just needs 220 and I don't need a neutral this should be easy. Run 2 hots off the box and ground the green to the box? (After checking to make sure there is not a "wild" hot.)
My huntch that you may reqired a netural due you may have 120 volt coil for the motor contractor the last car lift I did it have stragiht 240 volt no netural at all so it was not a issue but your lift that is a big question due I do not know which brand you have yet.

and the other thing most car lifts I ran into most will useally required 20 amp time delay fuse or circuit breaker but few will reqired 30 amp { only on super large lift or truck lift which i know that is typical } and you have fused bussbox drop off you will have to get fuse reducer to fit in there { I am not too crazy to do this other guys will confirm this part to make sure it is legit }

Merci.
Marc
frenchelectrican is offline   Reply With Quote
Old 09-23-2010, 02:01 PM   #7
Newbie
 
Join Date: Sep 2010
Posts: 6
Rewards Points: 10
Default


Thanks for the help! It is a Mohawk lift. 10K lbs. I guess I really need more information at this point. I'll try to take the measurements needed and hopefully get some detailed instructions.
berrmich is offline   Reply With Quote
Old 09-23-2010, 02:06 PM   #8
nap
You talking to me?
 
nap's Avatar
 
Join Date: Dec 2007
Location: sw mi
Posts: 7,551
Rewards Points: 6,290
Default


you also must realize the the wire connected to the bus head must be fused properly. The breaker feeding the bus is not proper fusing for a drop such as you are considering.
nap is offline   Reply With Quote
Old 09-23-2010, 02:28 PM   #9
Licensed Electrical Cont.
 
Speedy Petey's Avatar
 
Join Date: Feb 2004
Location: NY State
Posts: 7,828
Rewards Points: 2,006
Default


Quote:
Originally Posted by berrmich View Post
If I hook up 2 of the poles (leaving one empty) with my red and black wire and ground my white and green to the box... is that safe/correct?
Absolutely not!


Quote:
Originally Posted by berrmich View Post
This is how the old owner of the shop has this hooked up for one of the boxes already but not sure how much I trust that. He is not using the ground (green) just the 2 hot and neutral (white) which is grounded to the box.
This is very wrong. Please do not copy it.





This is a commercial shop, why not just do the right thing and hire an electrician? It is a write off anyway.
Speedy Petey is offline   Reply With Quote
Old 09-23-2010, 02:41 PM   #10
Member
 
Join Date: Aug 2010
Location: north central pa
Posts: 589
Rewards Points: 1,005
Default


it's sounding as though your bus duct is delta 240vac 3 phase. out of it you can get 240 3 phase (using all 3 connections) or 240 single phase (using 2 of the 3), and a service ground (green) this is not a neutral. if your equipment requires 120vac (something you need to check), you'll need a wye system to tap from, not delta. and the fuses need to be sized to protect your wire, 20 amps if you are using 12 gauge wire.

"they are 60's. Should be plenty for what I'm doing. It is for a car lift. The instructions (I don't have the lift yet.. comes tomorrow) say I need 12/4 SO wire"

i second mr petey
TimPa is offline   Reply With Quote
Old 09-23-2010, 03:52 PM   #11
Newbie
 
Join Date: Sep 2010
Posts: 6
Rewards Points: 10
Default


Ok.. well I talked to Mohawk. They do require 2 hots, neutral and ground. I'm assuming there must be 240 and 120 components on the lift. (is that a safe assumption?) I did the right thing last time and was charged $1,100 for the guy to run a 30 ft cable to the box. This was 3 phase which was a pretty simple connection. I think people should be payed for their knowledge but this seemed a little rediculous. This is a commercial building but it is for personal use (working on cars, ect..). So no write off. I may try to find an electrician that I trust to at least look at the setup and explain some of these things. That would be well worth a little extra money.

-Mike
berrmich is offline   Reply With Quote
Old 09-23-2010, 08:03 PM   #12
" Euro " electrician
 
frenchelectrican's Avatar
 
Join Date: Apr 2006
Location: WI & France { in France for now }
Posts: 5,369
Rewards Points: 2,000
Default


If you have wye connection supply { 208 volts } it should be not too bad however again the safest methold is get a hold of electrician { some can do at diffrent time so talk to them see what they say }

Few car lifts I dealt they can get them in three phase motor and for small upcharge you will not have to worry about dammed netural at all.

Few car lifts I know some have small transfomer in there for contractor / lift limit switch so that is the other option.

Merci.
Marc
frenchelectrican is offline   Reply With Quote
Old 09-24-2010, 11:14 PM   #13
Newbie
 
Join Date: Sep 2010
Posts: 6
Rewards Points: 10
Default


Thanks french... sure enough they do have a 3 phase option! He is going to switch it out for me for 120 bucks. Well worth it. Now the wiring will be simple enough for me to do. Just need a couple fuses and hook things up to the box.

Thanks for the help! I've learned alot about 3 phase with this little project. Even though it turned out to be simple (this project.. the concepts are still fairly complex to me).

-Mike

Last edited by berrmich; 09-25-2010 at 09:26 AM.
berrmich is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply


Thread Tools
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
120/208 120/240 high leg delta panel florint23 Electrical 15 06-07-2010 10:14 PM
1 phase to 3 phase diesel boy Electrical 12 05-05-2010 11:57 AM
Want to add a single phase Subpanel to three Phase Main meglomachinist Electrical 19 09-10-2009 03:46 PM
How to power a 120/240 volt 3 phase oven in a building with 120/240 volt single phase wantsomegetsome Electrical 9 05-04-2009 10:49 AM
120/208/1 phase wiring questions JohnJon Electrical 11 08-31-2008 11:28 PM




Top of Page | View New Posts