Wiring 3 Phase 4 Wire 240Volt Breaker?

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Old 04-13-09, 09:02 AM
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Wiring 3 Phase 4 Wire 240Volt Breaker?

So I am putting a computer in my office (a big one) that has a 4 wire hubbell connector. The manual says I should have 240Volts between L1 and L2, L2 and L3, and L3 and L1. The 4th wire is a ground.
This is 60amp 240volt, so should my breaker be a 3 pole breaker?
It will be in a commercial building so I am out looking for one to rent I am trying to find one that is already wired correctly.
I don't think I can use regular home 120volt service which would be a two pole breaker (240/208) with ground and neutral.
Anyone here wired something similar?
 
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Old 04-13-09, 09:16 AM
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You want a building with 3 service and office space with a 3 4-wire load center.

You need to check with the manufacturer to see if you can use it on a grounded B phase system (I think that's what it's called). That is 3 3-wire, and one phase is grounded. It's cheaper to install, but your computer may not like the fact that one phase and ground are at the same reference.
 
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Old 04-13-09, 09:28 AM
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3 phase 4 wire

Originally Posted by ArgMeMatey View Post
You want a building with 3 service and office space with a 3 4-wire load center.

You need to check with the manufacturer to see if you can use it on a grounded B phase system (I think that's what it's called). That is 3 3-wire, and one phase is grounded. It's cheaper to install, but your computer may not like the fact that one phase and ground are at the same reference.
The ac/dc/converter says 3 phase 4 wire.
SO Pump in 3 phases of 240/208? and one ground back to neutral bus bar in main panel.
If I have one leg at 120volts that no good, my brief understanding of 3 phase on a corner grounded delta says one leg is 120V, no good.
kevin
 
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Old 04-13-09, 10:01 AM
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You're confusing phase-to-phase voltage and phase-to-neutral voltage. Your three-phase appliance only cares about the phase-to-phase voltage so a grounded delta type system would be okay for this machine. A three-pole breaker of the appropriate amperage would be required.

Check with the manufacturer to see if this will also run on a 208V system that is much more common in commercial office space. Most equipment that runs on 240V can be field converted or will automatically work on 208V too.
 
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Old 04-13-09, 10:15 AM
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Originally Posted by ibpooks View Post
You're confusing phase-to-phase voltage and phase-to-neutral voltage. Your three-phase appliance only cares about the phase-to-phase voltage so a grounded delta type system would be okay for this machine.

Check with the manufacturer to see if this will also run on a 208V system that is much more common in commercial office space. Most equipment that runs on 240V can be field converted or will automatically work on 208V too.
Thanks for all the replies.
I guess my issue is this:
Most of the commercial warehouses I have looked at have only 100amp 240 volt main panels.
This would be 120V(black), 120V(red), white, neutral.(like a house)
I believe what I need is 240v(black), 240v(black), 240v(orange), and ground to bus bar.
Is that 3 phase delta corner ground, or 3 phase wye?
It seems delta has a "high-leg", that would blow my system.
As above I cannot "convert" the system to run on anything but what it can.
I can run 60amp 240V, or 30 amp 480 volt, or about anything in between.
The manual says:
To verify the proper wiring for a 4-wire PDCA(Power distribution control assembly or basically the computers ac/dc power converter), use a DVM to measure the voltage at the in-line connector. Voltage should read 200 - 240 Vac phase-to-phase as measured between the connector pins as follows: L1 to L2, L2 to L3, L1 to L3.

Now I have looked at a few warehouses and I see 3 pole breaker and 2 pole breakers.
I found one with 480volt main with transformer, but did not look at y or delta specs.
kevin
 
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Old 04-13-09, 10:42 AM
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Is this similar to what you have?
Unpacking the PDCA

Bud
 
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Old 04-13-09, 11:34 AM
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yes but i have the ibm version

Originally Posted by Bud9051 View Post
Is this similar to what you have?
Unpacking the PDCA

Bud
I have the ibm version, power is the same.
I will email you a pic
kevin
 
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Old 04-13-09, 11:42 AM
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pictures of ac/dc/converter and cables



 
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Old 04-13-09, 12:18 PM
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Originally Posted by xkmail View Post
This would be 120V(black), 120V(red), white, neutral.(like a house)
The PDCA cannot operate on this single-phase system.

I believe what I need is 240v(black), 240v(black), 240v(orange), and ground to bus bar.
Yes, you do need a three-phase system, but the PDCA seems to be very flexible in the type of three-phase power it can use. There are a variety of color schemes which could be used (black, red, blue, orange, brown, yellow). It could run on a 208V, 240V or 480V system wired in a delta or a wye which should give you a lot of flexibility in finding a suitable site.

Is that 3 phase delta corner ground, or 3 phase wye?
Either would work as long as the voltage is within the specified range.

It seems delta has a "high-leg", that would blow my system.
A high-leg system would be okay.

Now I have looked at a few warehouses and I see 3 pole breaker and 2 pole breakers.
The breaker poles isn't always a dead giveaway, because the building may have a three-phase main panel which is then split out into several single-phase panels throughout the building for lights and receptacles. So even if you only see double-pole breakers, there could still be three-phase in the building..
 
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Old 04-13-09, 12:46 PM
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The breaker poles isn't always a dead giveaway, because the building may have a three-phase main panel which is then split out into several single-phase panels throughout the building for lights and receptacles. So even if you only see double-pole breakers, there could still be three-phase in the building..

Wow, thanks for the advise, as you are topic mod with 4200 posts I would have to take your word as gold.

Most small warehouses (under 1000 sq') seem to have 400-800volt drop at 240 amps, then it splits power to the individual units, 60-100amp mains (black, red, white, gnd-wrong power per previous post). However I have found a couple with a 480 volt main panel in the office, which feeds to a transformer which steps down to 240volt.
However on that one could I just put in a 30mp breaker on the 480 volt panel and feed off that?

As far as the sub panel goes I saw a huge 200amp panel and some had 3 pole breakers, I figure I would pull three "phases" from that and ground to the neutral bar right, considering if the breaker was the correct type.

I don't see how I could use a two pole 60 amp breaker and one 60 amp breaker unless I could sort out the three phases.

Thanks again, my problem is I can't drag a commercial electrician to every potential site to have him check the panel ya know.
k. brown

PS> bluevistarendering.com
 
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Old 04-13-09, 01:12 PM
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Originally Posted by xkmail View Post
However on that one could I just put in a 30mp breaker on the 480 volt panel and feed off that?
Unfortunately, the best I can say is maybe. There could be a 480V single-phase panel or it could be three-phase. That would require inspection by an electrician.

3 pole breakers, I figure I would pull three "phases"
If you have three-pole breakers, then you have three-phase power.

I don't see how I could use a two pole 60 amp breaker and one 60 amp breaker
You can't. A three-phase load cannot be used on a single-phase service.

Thanks again, my problem is I can't drag a commercial electrician to every potential site to have him check the panel ya know.
Certainly not during your first look. It would be a good idea to have one meet you there for an hour's consulting before you sign the lease though. Three-phase commercial systems are substantially more complex than residential wiring, so there are 100 what-ifs that someone on-site really needs to see before you can say with 100% certainty the site is adequate.
 
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Old 04-13-09, 03:46 PM
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Originally Posted by ibpooks View Post
...

If you have three-pole breakers, then you have three-phase power.
Yes, but you said earlier that corner grounded delta would be OK, and if that's the same as grounded B-phase, that system uses 2-pole breakers and is three-phase.

I am not an electrician and I don't mean to make this more confusing, but I sure was confused when I first encountered grounded B-phase and traced it back to a 3-phase primary.

http://forum.doityourself.com/electr...onductors.html
 

Last edited by ArgMeMatey; 04-13-09 at 04:34 PM. Reason: added link
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Old 04-14-09, 08:17 AM
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Originally Posted by ArgMeMatey View Post
Yes, but you said earlier that corner grounded delta would be OK, and if that's the same as grounded B-phase, that system uses 2-pole breakers and is three-phase.
That's true, but I also said a few posts back that there are some circumstances where a panel with two pole breakers might be able to supply three-phase.

I am not an electrician and I don't mean to make this more confusing, but I sure was confused when I first encountered grounded B-phase and traced it back to a 3-phase primary.
I agree. These types of systems can be very confusing and complex which is why there really aren't any "rules of thumb" with three-phase like there are with residential single-phase services. Every situation is different with some nuance of how the transformer(s) are hooked up or panels are laid out.
 
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