Electrical ??

[55 50 Ron]

Is this a 3 phase input.

 

[ken44520978]

It looks like 240 volt singles phase. The center conductor is tapped white as a neutral.

 

[Stan Coryell]

It's 3 phase. 3 pole breaker and separate neutral conductor.

Edit:
I zoomed in...
It's a Square D Type QO panel. The main says 240volt.

Make sure you check voltage if you plan on cutting into the panel. It would likely have one phase that is 208 VAC to neutral (high leg). Phase to phase will still read 240 VAC. The other two phases will read 120 VAC to neutral.

It use to be common around here. Most new 3 phase services are 120/ 208 VAC.

 

[olddavid]

It's 3 phase. 3 pole breaker and separate neutral conductor.

Edit:
I zoomed in...
It's a Square D Type QO panel. The main says 240volt.

Make sure you check voltage if you plan on cutting into the panel. It would likely have one phase that is 208 VAC to neutral (high leg). Phase to phase will still read 240 VAC. The other two phases will read 120 VAC to neutral.

It use to be common around here. Most new 3 phase services are 120/ 208 VAC.

It's 3 phase or modified 3-phase. You don't switch the neutral with a breaker.

 

[Stan Coryell]

It's 3 phase or modified 3-phase. You don't switch the neutral with a breaker.

I'm not familiar with modified 3 phase. Could you elaborate?

PS my money is on B phase being the high leg. Someone marked it with tape.

 

[olddavid]

I guess the correct title isn't modified 3-phase but "High Leg Delta". My bad.

High Leg delta connection in a transformer - Explained

If the secondary of this transformer is delta then, the centre of any one of the phases is centre-tapped and grounded. This is called High Leg delta connection.

www.electricalclassroom.com

In the "star" configuration the transformer secondary coils have a common connection which becomes the neutral. It yields 120 volts to neutral/ground from each leg and 208 volts between any two phases.

 

[Stan Coryell]

I guess the correct title isn't modified 3-phase but "High Leg Delta". My bad.

High Leg delta connection in a transformer - Explained

If the secondary of this transformer is delta then, the centre of any one of the phases is centre-tapped and grounded. This is called High Leg delta connection.

www.electricalclassroom.com

In the "star" configuration the transformer secondary coils have a common connection which becomes the neutral. It yields 120 volts to ground from each leg and 208 volts between any two phases.

Ohhh. Terms are regional. No problem!

We would say "240 Delta". A lot of restaurants used that here. I haven't done light commercial since 2001.

208 VAC toaster, coffee maker, walk in cooler, sometimes lights.

3 phase 240 VAC for the roof top A/C.

 

[55 50 Ron]

Great information and thanks. A place where I volunteer had an air compressor motor fail. The motor was repaired, and after repair would not power the compressor. Whenever the compressor switch was turned on the voltage at the motor dropped to about 35 volts.

Checking at the panel breaker it was also about 35 volts with the compressor switch on. This is just one small part of what we measured or thought we corrected.

We lost track of voltages we were measuring in the panel and not being full fledged electricians with this stuff we opted to call an electrician.

I suspected it is some sort of 3 phase, but I never studied this stuff at EE school. If I remember I'll post back after the problem is solved.

Thanks again for the information

 

[olddavid]

Ohhh. Terms are regional. No problem!

We would say "240 Delta". A lot of restaurants used that here. I haven't done light commercial since 2001.

208 VAC toaster, coffee maker, walk in cooler, sometimes lights.

3 phase 240 VAC for the roof top A/C.

I pulled that "modified" 3 phase off the top of my head which is dangerous at my age. You were right on warning Ron about the possibility of the "wild leg" (we called it) being 208 to ground. It could get a fella hurt. I can't tell from the picture whether it's a Delta configuration or a "Star (Yi)". Where I worked it was mostly "Star" but we used to attend church at a building that was configured "240 Delta".

 

[John T]

Thanks for Stan’s pictures and great explanations !!!!! Which I second

Sorry, Got here late but fyi in our area fwiw we called such service. Three Phase Four Wire and after that it could be Y (see Stans bottom pic) orrrrrr Delta (Stan’s middle pic) where one phase could be center tapped to get two legs of 120 yet still have 240 three phase for motors and HVAC. That was Red Leg Delta.. I never used the red high leg which was 208 single phase to Neutral but instead the two 120 legs for lights and receptacles and 240!for motors etc

The common buss was where the incoming big Neutral attached and both neutrals and grounds attached. My pure guess is the taped center wire might indicate it Might be 3P4W Red Leg Delta Stans middle pic

PS at one place I worked where they wanted a grounded versus floating Delta there was a 3P3W 240 Volt Delta with a corner ground.

Sorry us sparkies enjoy this chat even if boring to others lol

John T

 

[Stan Coryell]

I pulled that "modified" 3 phase off the top of my head which is dangerous at my age. You were right on warning Ron about the possibility of the "wild leg" (we called it) being 208 to ground. It could get a fella hurt. I can't tell from the picture whether it's a Delta configuration or a "Star (Yi)". Where I worked it was mostly "Star" but we used to attend church at a building that was configured "240 Delta".

I pulled that "modified" 3 phase off the top of my head which is dangerous at my age.

LOL!

I was taught to always check a 3 phase with a meter as you never know what you are dealing with. Where I teach at night, we have 13.2 KV, 277/480, 240 WYE, and 120/208 Delta. 9 out of 10 Rooftop Units are 480VAC, one is 208!

 

[olddavid]

I was taught to always check a 3 phase with a meter as you never know what you are dealing with. Where I teach at night, we have 13.2 KV, 277/480, 240 WYE, and 120/208 Delta. 9 out of 10 Rooftop Units are 480VAC, one is 208!

That's the safest way to find out. We had a lot of 480 Vac equipment in our plant and the lights ran on 277. We had an overhead 480 bus that ran through the newer half of the plant and transformers coming off of that to get 120 and 208. You need to know what you've got that's for sure. I'm retired now and I'm not a licensed electrician, but I learned a little over the years.

 

[Dusty MI]

I worked as a construction electrician.
I had a brain stroke a couple of years ago and have forgotten a lot of things. This brings back some memories.
Thanks,
Dusty

 

[John T]

I pulled that "modified" 3 phase off the top of my head which is dangerous at my age. You were right on warning Ron about the possibility of the "wild leg" (we called it) being 208 to ground. It could get a fella hurt. I can't tell from the picture whether it's a Delta configuration or a "Star (Yi)". Where I worked it was mostly "Star" but we used to attend church at a building that was configured "240 Delta".

That center leg being taped makes me think it’s a red leg center tapped Delta versus a Y which wouldn’t need any leg marked but can’t know from here ??? Voltmeter time indeed

John T

 

[John T]

I worked as a construction electrician.
I had a brain stroke a couple of years ago and have forgotten a lot of things. This brings back some memories.
Thanks,
Dusty

Not to feel bad old sparky friend I’ve had no stroke but still can’t remember grrr

John T

 

[John T]

It looks like 240 volt singles phase. The center conductor is tapped white as a neutral.

The Neutral is NOT switched ........

John T

 

[Dusty MI]

That center leg being taped makes me think it’s a red leg center tapped Delta versus a Y which wouldn’t need any leg marked but can’t know from here ??? Voltmeter time indeed

John T

Maybe just wanted to know which wire was which, and just used some red tape that they had.

Dusty

 

[drsportster]

I would not believe that gray tape is indicating neutral but possibly a guy ran out of red tape to mark a high leg panel .It is 3 phase

 

[55 50 Ron]

Here's the info about the "fix" to this problem. The electrician found a switch open on a pole from the power supplier. Power supplier came and fixed it.

Theory is that a racoon was climbing the pole and pulled thr switch open so not all inputs were on. Now even the shop lights are brighter !!!!!!

Ron

 

[olddavid]

Here's the info about the "fix" to this problem. The electrician found a switch open on a pole from the power supplier. Power supplier came and fixed it.

Theory is that a racoon was climbing the pole and pulled thr switch open so not all inputs were on. Now even the shop lights are brighter !!!!!!

Ron

Thanks for sharing the solution. Glad you got it fixed!