Voltage issues and dimming lights

[aelectricalman]

Today I was called to a job to troubleshoot. The client said that when a light switch was turned on, the rest of the lights dimmed and stayed dim until the switch was turned off. Normally when this happens I look for a phase burned out on a main or pitting on a branch circuit breaker. This was In fact the issue....there was pitting on the branch circuit breakers and there was signs of obvious overheating. However, the utility was called to the home before we were. The poco told the client there was a spark in the meter base. We investigated for 30 minutes and finally as the AC turned on there was our spark. However, the spark wasn’t coming from the meter. It was coming out of the 3 inch EMT from the pad mounted transformer The EMT went underground 20 ft until across drive then the rest was direct burial to the XFMR. This EMT had a bond Bushing in meter and was bonded to the neutral terminal on the meter. Note: There were parallel 2/0 feeders in the Single 3 in EMT from utility. The panel was grounded to earth.

Is there any way this issue is related to the Issue inside the house. Anyone have any thoughts? Thank you in advance.

 

[aelectricalman]

Right off the bat, the 3inch EMT is bonded to the neutral conductors in the meter. Next, the ground rods are required by POCO to be connected in the panel. The first POC should be in the panel.

 

[LarryFine]

Sounds like the EMT was being forced to carry neutral current. Confirm by measuring a higher voltage from one line to the neutral in the panel while intentionally causing the dimming, and a lower voltage from the other line to the neutral.