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Posted By: renosteinke 3 phase panel on 1 phase service - 01/04/07 08:08 PM
Chad Fabry, a home inspector, came across this darling:

[Linked Image]


Now, I wonder ... with electricity flowing "out" one half of the breaker, and "in" the other, is the electromagnetic part of the breaker made inoperable?
Posted By: Ann Brush Re: 3 phase panel on 1 phase service - 01/04/07 08:22 PM
What a gem! Depending on the slot you used for each SP breaker you could get 0 or 120V and for each DP breaker you could get 120 or 240V (to neutral), really great piece of work - love how the L1 and L2 lines are beautifully numbered, then hacked into a 3-ph panel.
Posted By: Luketrician Re: 3 phase panel on 1 phase service - 01/04/07 08:45 PM
So this wasn't existing was it? Seems that there would be a definite balancing issue for the neutral conductors on most, if not all mwbc's. Another good example of someone knowing just enough to be dangerous.

Luke
Posted By: JohnJ0906 Re: 3 phase panel on 1 phase service - 01/05/07 01:47 AM
Is that rust on the neutral lug? (top right corner)
Posted By: wa2ise Re: 3 phase panel on 1 phase service - 01/05/07 02:11 AM
Seems that if someone was to backfeed the 100 amp breakers as a main, they could have just tied the 3rd bus lug to 2nd bus lug. (Far as I can see, there's nothing on the bus lugs). Or just take the sltrsfy live output of the 70 amp breaker and loop that up to the 3rd bus lug. Would that make it a sub-panel imbedded in the main panel? [Linked Image] Not that that matters, this all violates code....
Posted By: NORCAL Re: 3 phase panel on 1 phase service - 01/05/07 02:43 AM
Only one close to that is one I worked on where they had fed a 3 phase panel from a single phase tranformer and jumpering from center lug to right hand lug whole thing was a blooming mess.Another comment, seeing that is a I-T-E panel was jumper still in place on the split neutral? I am assuming its a sub not a main panel, otherwise grounding and grounded are bonded.
Posted By: Tesla Re: 3 phase panel on 1 phase service - 01/05/07 03:58 AM
The installer missed the obvious jumper location: at the bus lugs at the top, still unused.

Our man has jumpered A and C phases ( Black and Blue )

Putting '#2' at position #3 is too cute.

Said jumpering will not produce any single pole breaker with a voltage of 0. All will show full voltage.

Double pole breakers will only show 0 volts when tapping Black and Blue. Red/Blue and Black/Red combinations will deliver full voltage.

Such a set-up makes one think that the panel was boosted from a commercial job way back when. The price difference would always stop a legitimate player from wasting a three phase panel so.

Alternately, it's a second hand panel rigged up by a tradesman. Still, a waste of value.
Posted By: mamills Re: 3 phase panel on 1 phase service - 01/05/07 02:42 PM
Though this is certainly among the least of the problems here, isn't that 100a "main" breaker supposed to be fitted with some type of retaining screw if it is to be backfed like that (in any kind of panel)?

In one case, I saw a three phase panel being fed by a single phase service. The "C" buss was not being used at all - the breakers were located only on "A" and "B". Still not right, but at least someone was thinking about the neutral balancing issue. regrettably, the cover had long since disappeared, so it was all too easy to view the interior [Linked Image].

Mike (mamills)

[This message has been edited by mamills (edited 01-05-2007).]
Posted By: tajoch Re: 3 phase panel on 1 phase service - 01/07/07 07:33 PM
A couple of years ago I was house hunting and saw one just like this, 3ph panel on a single phase service. They just didn't have any breakers in place on C phase.......
If one panel wasn't bad enough, there was a 3ph subpanel in the utility room........
Posted By: yaktx Re: 3 phase panel on 1 phase service - 01/09/07 02:29 AM
I found (and corrected) one of these in an old warehouse, where an existing 240V delta had been rewired for 120/240.
Posted By: EV607797 Re: 3 phase panel on 1 phase service - 01/09/07 03:16 AM
Shamefully, I have to admit that I did something very similar to this in my early years in the trade. My boss at the time was very patient with me and allowed me to take on side jobs for friends and family. He would even bail me out if I got in over my head. This time, I really screwed up.

I had some close family friends who owned a lighting supply store. They had expanded and needed to power up an addition of lighting displays. My solution was to install a sub panel for this new display area.

They had a 400 amp, three phase service, and it looked like a pretty straight-forward job. About a 75 foot run of SER cable, another disconnect and the panel was all I needed. This was an old place and the service consisted of a trough with four fused disconnects. I managed to muster up the guts to open the main (and unfused) trough, cut a hole and place another disconnect to feed the sub panel. My boss even came in and tied everything in for me live since I was afraid to do it.

Just as he was finishing, he asked me if I need any orange tape. Being 17 at the time, I asked him "why would I need orange tape, I have white, red and blue"?

I guess you know the rest of the story. It was a high-leg service and the C phase was of absolutely no use in the sub panel. This was my first attempt at working with three-phase services of any kind since all we did was residential. My suggestion was to just skip all C phase spaces in the sub panel, but he insisted that the only way he'd let me do that would be if we cut the third phase completely off at both ends so that it would be impossible to reconnect.

He taught me something very valuable that day and he didn't have to say a word about how I was doing this wrong. He let me make the mistake on my own and pay the price on my own without hardly saying a word. What a great teacher he was. I never made that assumption again and that was nearly thirty years ago.


[This message has been edited by EV607797 (edited 01-08-2007).]
Posted By: RSmike Re: 3 phase panel on 1 phase service - 01/09/07 06:00 PM
That last story reminds me.....

During my college years I worked at an electronics shop. One day the members of a band comes in complaining about the local bar. Turns out they smoked all their equipment because "the voltage in the place was messed up at 211 volts." I spent an hour trying to find several suitable replacement cube transformers which had smoked. I never thought about it....

Later that year while also employed by a sound and lighting company we arrived at this same bar to set up for a band competition. Upon entering the basement to connect our temp subpanel we notice every other breaker missing and confirmed a high leg voltage of 208 with a VOM.

It was shortly after that I realized the band failed to recognize this oddball service. They also made a major error by not checking the voltage with a meter.

This was back in my hometown and the bar has been there forever. My only guess is the service was left behind from some industrial stuff in the area and they got what the PoCo already had in place.

In retrospect it was strange to see this service...with every other breaker left open.....just waiting for some poor sole.

RSlater,
RSmike
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