How To Measure or Check for 3 Phase Voltage

how to measure 3-phase voltage on 3 phase Square D panel
going to each phase A phase to neutral measure B phase to neutral
C phase to neutral then measure phase to phase
this is a 3 Phase balance system
known as open Delta this is a 120-240 volts 3 phase system
you will have 120 volts on each leg 240 volts phase to phase
on B phase ( high leg) 208 volts to neutral


Thanks for watching!
- David

[jonesacnaples]

I hope you find this video helpful...thanks for watching from Jones Air Conditioning & Electric in Naples, FL!

[Pilinchi]

David, thanks for posting this video. THIS is what I am talking about, straight to the point and you stayed on target with your video. All these other folks recording themselves with sticks and getting off track is just taking too much bandwidth., Thanks again for your video. :-)

[jonesacnaples]

You are 100% correct, I did not install this panel or have any red tape. Just trying to give a little explanation of how to measure 3 Phase voltage. I appreciate your comment, take care my friend.

[jonesacnaples]

This is a Delta system the center phase or high leg always has higher voltage providing by the power company for commercial business to operate large equipment at lower power rate to save power, also you will have 120 power for office equipment. Hope this helped. Thanks or asking.

[dougspair]

Well, here in California, this is called 240 DELTA with high leg. That center power lnput (B) should have RED tape on it. That's 208 to neutral. Neutral is center-tapped between A and C at the transformer on the pole. There's NO high leg on a WYE (or sometimes called STAR) system, all phases are 208 to each other, 120 to neutral.

[jimmysegovia]

thank you Jones for sharing knowledge is power, have a nice weekend!!!

[jonesacnaples]

Just a simple explanation of, how to for the beginner electrician. Thanks for your comment.

[djscrizzle]

PROTIP: The National Electrical Code requires all high leg conductors to be marked orange.

I'd go as far as tossing a roll of Scotch #34 orange tape in my tool bag, to mark them as I came across them, as a courtesy and to meet a very easily (inexpensively) achieved part of the NEC.

See NEC article 110.15, which started requiring the identification as early as the 1975 edition. The high leg wire is to be durably marked orange or by other effective means. Also it's required to be marked anywhere the high leg and Grounded Conductor [Neutral/mid point/0v] is also present, such as at a panel, or a motor starter, etc

Before 1975, common practice was to mark the wire on the high leg red, stemming the nick-name "Red-Leg Delta".

[jdhart]

one of the best well explained tutorial out there on this subject ...thanks

[ivantaylor]

hi! David! you explained very well and easy to understand, this is very valuable for my future career, thanks you.

[chennemeyer]

I built a rotary phase converter and was testing between the leads to find one hot relative to neutral (the manufactured leg), thanks to this video I can see that this is a duplication of the normal measurements with "real" three phase supply.

[samsunglg]

Thanks for uploading, this answers a few fundamental questions that I have in mind.

[johnkerley]

From what he said and showed, this is Delta with one coil center tapped. This type of Delta does have a high leg.

[jonesacnaples]

This was just a quick explanation, you have to listen to it close to get the understanding. I am going to do another one and explain it much better. Thanks for watching, and your comment.

[notoriouskelly]

Thanks for the quick and simple demonstration.

I just thought of this question and you answered it!

[davidowen]

you dont ALWAYS have a high leg in three phase three phase

[daviddelacruz]

David what if your b phase bus bar isn’t producing voltage in a 3 phase main panel?

[Firehawk]

Never had arcflash training... Never measure at the feeds. measure at breakers.

[jonesacnaples]

It can be it. All depend on the power company, you must always check for high leg in order to hook up your Phases correctly. Thanks for asking.

[theadventuresofvanwinkle]

very helpful and thanks for giving code on B phase