Here's a first for me. I get a call last Thursday from an A/C company who's A/C tech disconnected a neutral wire from a ceiling mounted air handler (the neut was bonded to the A/C frame), and witnessed an arc flash as the lights died in this small restaurant.
Clearly a faulty neutral connection.
I check the panel, get nothing from ground to neut. I check the main service and find the result of multiple remodels and 4000 Black Widow spiders... scary spaghetti. There are feeders looping between sections, feeders entering the top-back in the unmetered sections, no way to determine which feeder belongs to which neut... utter chaos. I start checking all the landed neutrals in the sections and thought I found the problem when I came across a very loose neut... tightened it up and it made no difference to this suite. I start looking for hidden j-boxes in the feeder that might contain a bad splice and realize it might be a long night as the feeders go through virtually unaccessible attic space. I'm coming up empty.
Back at the main service, for some reason I start to count landed neutrals vs the # of meters in the four 6-meter sections, and realized there was missing neutral. ???
What I ended up finding is the 3/0 neut for the 200 amp panel serving this suite ( a multi-tenant commercial building) taped up and jammed out of sight behind cob-webs and buss-bars. My best guess is that some genius added a meter base at one point while this suite was unoccupied and for some reason didn't have a lug to land its neutral, so they stole this suite's lug. Later this suite was occupied and by chance someone had erroneously grounded a #10 neutral in this air-handler giving potentially 200+ amps a way home through this A/C's frame and branch circuit grounding.
It looks like this restaurant has been operating like this for 1.5 years.
I think I now have truly seen it all. I just can't believe this place never burnt to the ground. Wild stuff.
Clearly a faulty neutral connection.
I check the panel, get nothing from ground to neut. I check the main service and find the result of multiple remodels and 4000 Black Widow spiders... scary spaghetti. There are feeders looping between sections, feeders entering the top-back in the unmetered sections, no way to determine which feeder belongs to which neut... utter chaos. I start checking all the landed neutrals in the sections and thought I found the problem when I came across a very loose neut... tightened it up and it made no difference to this suite. I start looking for hidden j-boxes in the feeder that might contain a bad splice and realize it might be a long night as the feeders go through virtually unaccessible attic space. I'm coming up empty.
Back at the main service, for some reason I start to count landed neutrals vs the # of meters in the four 6-meter sections, and realized there was missing neutral. ???
What I ended up finding is the 3/0 neut for the 200 amp panel serving this suite ( a multi-tenant commercial building) taped up and jammed out of sight behind cob-webs and buss-bars. My best guess is that some genius added a meter base at one point while this suite was unoccupied and for some reason didn't have a lug to land its neutral, so they stole this suite's lug. Later this suite was occupied and by chance someone had erroneously grounded a #10 neutral in this air-handler giving potentially 200+ amps a way home through this A/C's frame and branch circuit grounding.
It looks like this restaurant has been operating like this for 1.5 years.
I think I now have truly seen it all. I just can't believe this place never burnt to the ground. Wild stuff.
