120/208 panel and dead SPARE breakers

[Greg1707]

I apologize if this is a stupid question. I do not have much experience with commercial work.

I was called to a small office building. For two years the lights in one of the offices have not worked. I found the correct breaker and determined there was no current from the breaker. I switched the wire to a nearby SPARE breaker and there still was no power. I then realized there was no power in every third SPARE breaker.
I double tapped to an adjacent breaker and all is good.

The panel was labeled 120/208 volts.
There were five conductors connected to the panel (L, L, L, N, G). I did not confirm that the third leg had power.

What is up with every third SPARE breaker with no power?

 

[tom baker]

You have lost a phase from the service or feeder. What is the line voltage?

 

[jim dungar]

Get in the habit of taking all possible voltage measurements, not just the easy to make Line to Ground ones.
L1-L2
L2-L3
L3-L1
L1-N
L2-N
L3-N
L1-G
L2-G
L3-G
N-G

 

[Little Bill]

It could be fed from a Delta high leg and they skipped the high leg to avoid having 208V to ground/neutral. If it had L-L-L-N present, I bet the high leg was not connected at that panel or from where it was fed from.

 

[tom baker]

It could be fed from a Delta high leg and they skipped the high leg to avoid having 208V to ground/neutral. If it had L-L-L-N present, I bet the high leg was not connected at that panel or from where it was fed from.

That would the panel in question samewhat safer.