Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
I don't have much experience with DB Aluminum conductors of the 1960's.
I got a call to look at a Direct Burial (DB) feeder. It was individual AL conductors 120/240 service DB. The breaker has tripped on occasion on only one leg. I decided to megger the run as I was told it was DB and it was working when I arrived and I was assured that no shorts or faults were present. All breakers were on and functioning. So de energized and I removed the conductors from the terminals and Meggered them with a Biddle Digital Megger. I measured only 16M.
The underground run is roughly 240' 1/0 AL. I have never seen a megger reading so low in a functioning feeder before. I had read that 1 megohm is good for this voltage. This seems odd as I have Megged new conductors of similar length and show many times greater.
My question are these conductors on the way to failing completely and maybe tripped the breaker due to a fault that blasted clear for the time being?
I got a call to look at a Direct Burial (DB) feeder. It was individual AL conductors 120/240 service DB. The breaker has tripped on occasion on only one leg. I decided to megger the run as I was told it was DB and it was working when I arrived and I was assured that no shorts or faults were present. All breakers were on and functioning. So de energized and I removed the conductors from the terminals and Meggered them with a Biddle Digital Megger. I measured only 16M.
The underground run is roughly 240' 1/0 AL. I have never seen a megger reading so low in a functioning feeder before. I had read that 1 megohm is good for this voltage. This seems odd as I have Megged new conductors of similar length and show many times greater.
My question are these conductors on the way to failing completely and maybe tripped the breaker due to a fault that blasted clear for the time being?