Things that make you go Hmmmmm.

[Azsparky86]

Greetings, I came across something interesting here, hopefully one of you folks can explain....at a restaurant, 3- 200A 3 phase 120/240 42 space panels. Voltage readings were 120v to ground and neutral on A and C phase, B phase seems to have a high leg, of course, phase to phase readings were common 240V, I realized there were many single pole breakers on B phase !!!!! I performed readings at breaker(s) output to ground and neutral and all were 120V !!, then I took readings again at line and load side of MCB , on B phase, ...180V ....bussing in panel was at 120V....:blink:....I am not understanding this !!!! , what am I missing here?, any input would be hopeful and helpful....THX....Dean

 

[ActionDave]

What brand is the panel? I remember working on an old SQD that was bussed B,C,A. The high leg was still on B, but it was in a different breaker position than one was used to seeing.

Also some old high leg systems have high leg on C.

 

[FionaZuppa]

waiting in a line to buy a $2 item and you expect that line to go rather fast, but for some reason it takes 30min to get through checkout, makes me go " hmmmmm, hmmmmmmm, hmmmmmm ", a few times while waiting

 

[Dennis Alwon]

So you are saying that there was a voltage difference when measuring before the breaker and after the breaker? This doesn't seem possible unless there is some special breaker that can regulate the high leg.

It certainly seems like you have a delta 3 phase but I have no idea how the voltage after a breaker changes

 

[ptonsparky]

Take a voltage reading line to bussbar on each phase. Some one may have modified the panel.

Makes sure of your readings.

 

[JFletcher]

Welcome. Either it has a high leg or it doesn't.... "B phase seems to have a high leg" does not compute. It would be possible to use the high leg to run single phase 208V loads with a neutral, hence your apparently seeing 1p breakers on it. This is rarely done and when it is, it's usually done wrong. That you have 180V instead of 208V seems to suggest there is a pretty massive voltage drop on the high leg.

Breakers cannot magically transform bus voltage into a different line voltage.

 

[Jraef]

Bad connections with your meter probes?

 

[kwired]

Can you please clarify what two points you were measuring 180 volts between?

You possibly describing a bad "B" pole on the breaker and the 120 to ground you are seeing is "back feed" voltage through loads connected to A or C phase as well as to B phase? 180 is maybe what you read from line to load terminal of the B pole of the breaker?