I need some expert assistance...

I think that I have an open neutral on the power company's side. They came out to look at it today and didn't fix anything, and I would like someone else to evaluate my conclusion before I call them tomorrow.

This is a commercial building that I am remodeling. It has been vacant for some time before I bought it. I noticed the problem because my lights were getting dimmer and brighter depending on whether the saw would be running or the air conditioner would kick on. I'm not talking about just dimming when a large load is applied - I'm talking about the air conditioner kicks on and the lights get brighter.

So I started doing a little investigating online to figure out a possible problem and came up with an open neutral. Primarily, this conclusion arose because depending on the load, I am measuring 100 volts on one leg and 140 on the other. (FYI - I did add a couple light circuits and replaced the main breaker box - this is in an area that isn't in city jurisidiction). So today after the city didn't do anything (I wasn't present when they came - building still vacant during remodel), I started checking a little deeper.

Here is the setup: I have a 100 amp outdoor panel after the meter can. That runs to a 100 amp interior panel that I have all the individual circuits on. I turned off all but one breaker and put a 7 amp load on that breaker (vacuum). I started measuring amperage at the interior panel. I have 7 amps leaving the circuit breaker going to the receptacle (for vacuum). Next, on one of my hot leads in to the panel, I am pulling 7 amps. The other lead is not pulling any amperage. No amperage on ground either. There is 7 amps on the white neutral (returning to exterior 100 amp breaker). I go out to the outside panel and 7 amps going to the interior panel on one lead. None on the other and 7 amps on the neutral going to the bus bar where the neutral, service neutral and ground are tied together. There I measure no amps leaving on the service neutral to the meter, but there is 5 amps leaving on the ground (I figure the other 2 are seeping out on the metal conduit). I climbed on the roof and carefully measuring amperage at the weatherhead, there is 7 amps on one lead, none on the other and none and the neutral.

I know that is a LONG explanation, but I guess my main question is am I right in my conclusion that this has to be an open neutral on the power company's side? Every circuit, regardless of whether it is a table saw or a overhead light, causes a voltage shift when it is energized. If it was an open neutral on my side, it wouldn't affect every circuit would it?

Any guidance would be appreciated. I know there are some smart people out there...

Very good trouble shooting!
You definitely have an open service neutral , and the grounding electrode system is providing the return path.

This needs to be correct ASAP.

Shut the power off completely, and keep it off until the problem is corrected.

An open neutral conditon can cause great damage, which has not occurred yet due to the ground acting as a return.
The ground is now energized, and this can cause injury to someone coming in contact with any bare metal that is in the building intended to be grounded.

This is a dangerous condition and should be corrected right away.

Good thing the building is vacant and it was detected before occupied.

I would also go through all the panels, breakers, even the meter can looking for any other possible loose or damaged connections before final occupancy. Being vacnt s for some time, and possible poor maintenance can cause an electrical system to fatigue.

Electrical equipment should be inspected at least annually, per manufacturers recommendations as a preventative measure.

I would also check the grounding system for any loose connections or corrosion.

Thanks for taking the time to reply.

I have been shutting the power off nightly after diagnosing this problem (it is only on when I am there and I have quit using expensive power tools - unfortunately it won't damage a paint brush... )

I wanted to get some other feedback as I have read horror stories about getting the power company to take people serious about there being an open neutral on their side.

Now I will feel better pushing a little harder...

Thanks again!