[Gand0lfTheGray]

I am doing a job for a customer in a strip mall and when we started demolition the power wasn’t hooked up. Upon firing up the unit panel and beginning to commission the existing electrical, I began finding all sorts of terrible wiring mistakes and bizarre electrical effects. Circuit loops, double feeds, shoddy connections, jam packed boxes, chattering contacts just to name a few You’ll never guess what the storefront used to be… a computer/phone repair shop! So it’s a classic case of “I can do this myself, I’m a computer guy”😂
I’ve managed to tear out all of the existing garbage while salvaging the home runs and useful whips to re-connect properly but there is one big problem; the panel feeds are severely under volted… it is a 3 phase 120/208v system and here are my measurements:
A: 120v
B: 55.5v
C: 65.5v
A-B: 176.4v
B-C: 9.4v
C-A:185.5v
Whatever is happening, it is upstream of the unit panel. Obviously this issue falls under the purview of the property manager, but my customer took the opportunity to highly recommend me to the strata company so now I have an email from them requesting my services, which I am luke warm on considering my current work load. What I think I am seeing in these numbers is a split phase between B and C. It’s like 120v is being divided between those two lugs and that’s why I’m only getting 10v between them. Makes me wonder why the computer store went out of business!
Anyways, what do you guys see happening here and what would the potential solution be? I just want a sounding board before I issue a work order and find myself tits deep in some ungodly mess! Thank you 🙏🏻

 

[wcord]

Your B and C phase fuses are blown.

 

[macmikeman]

Toss that Klein Meter and buy a proper Knopp tester..........

 

[Gand0lfTheGray]

It just hit me! Did they hook up 120/240 single phase to a three phase transformer? A-B and A-C add up exactly without the route 3 correction…

 

[MHElectric]

What is a service savant?

 

[Gand0lfTheGray]

Your B and C phase fuses are blown.

But how am I still getting voltage on B and C?

 

[MikeFL]

Did you open all the breakers and measure at the lugs?

 

[Gand0lfTheGray]

Toss that Klein Meter and buy a proper Knopp tester..........

It’s what we have on hand at the moment 🤷🏻‍♂️

 

[Gand0lfTheGray]

Did you open all the breakers and measure at the lugs?

Yes

 

[Gand0lfTheGray]

What is a service savant?

One who can solve a problem simply by gazing upon it

 

[wcord]

Yes

Well, that negates my solution. No feedback thru the circuits.

 

[SWDweller]

Where I live the tenant is legally able to go back to the meter for any inspections they want to make. Is this space individually metered? Owner meter or POCO?
Check at the service or meter location for voltage.

Wonder how the heat is working?

 

[Dennis Alwon]

So you shut off all the breakers and your measurements are at the main lugs. If that is correct then you have a bad breaker. Check the voltage at the main breaker with all the breakers off except the one serving that area.

 

[wcord]

Wild guess as I dont have a lot of experience with Delta systems but open Delta where one or both of the feeders are grounded out? Had that happen when the roofer drove his screws thru the ceiling run conduit. No ground indicator to show the problem, but eventually I figured it out.
Too many years ago to remember the voltages, but they were really wild like these.

 

[joe-nwt]

It's a strip mall. If this is the only panel with problem voltages and it's upstream from the unit panel, there won't be much to check out to locate the problem. Breaker, maybe a transformer if the mall is fed with 600V and each unit has it's own transformer, and a feed. If you're not comfortable with 3PH, then pass.

 

[emtnut]

I'd measure with the proper meter first, then go from there.

I wouldn't rule out ghost voltage depending on how the service is run (ie, to legs are down)

Gand, the 120V (if you add B and C to gnd readings) just put a load on it and see what happens.

 

[emtnut]

What is a service savant?

I think he's calling us we tar did

Savant syndrome is a rare condition in which someone with significant mental disabilities demonstrates certain abilities far in excess of average.

 

[Wirenuting]

I think he's calling us we tar did

Savant syndrome is a rare condition in which someone with significant mental disabilities demonstrates certain abilities far in excess of average.

Well I’m a Sofa-King We Tar Dead type.

 

[LARMGUY]

I think he's calling us we tar did

Savant syndrome is a rare condition in which someone with significant mental disabilities demonstrates certain abilities far in excess of average.

Rainman, was a savant.

 

[Mikeyz]

I have had similiar weird readings like that before and once the the problem was a loose neutral in the meter base and another was a damaged neutral between the pole and meter .
I would start with making sure all connections are good and if they are the utility provider can load test the feeds to see if one is bad