Had to replace a 100A service on my neighbors house yesterday when a tree fell on it. I had a 100A meter combo base with a main breaker in it so we used it. There is about 4ft of #2 SEU cable comeing from the meter base into a old fuse box in the basement. Thats #2 SEU with 3 wires. My question is since I now have a 100a main breaker outside at the meter, should we have run 4 wires from the meter into the fuse box and seperated any grounds and nuetrals from branch circuits in the fuse box?
Main breaker at meter base
- Thread starter wormy
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes, you should have used SER cable from the service disconnect to the panel.
busman
Senior Member
- Location
- Northern Virginia
- Occupation
- Master Electrician / Electrical Engineer
Agree, you need SER.
Mark
Mark
jetlag
Senior Member
- Location
- Eatonton, Georgia
Old services were wired that way without an outside disconnect, you can still wire them that way around here if the meter and inside panel are back to back or also if they are mounted in the same wall stud cavity ,some places let you by if seu is 5 ft or less to panel. But when you installed the outside disconnect every thing changed then , you have to run 4 wires to the panel and isolate the neutrals from the metal encloser . The old box might not even have an isolated neutral bar. You might can isolate it just by removing a bonding screw
jetlag
Senior Member
- Location
- Eatonton, Georgia
I forgot to mention in my other post . I am curious how that passed inspection, or if not have a permit how did you get the power restored , around here the poco wont restore until been inspected. I guess you could have cut the drop at service mast your self and put it back hot, Ive done that a few times myself . Also what did you do about the seal on the meter?
Yea we had to get it inspected. My neighbor called the power company when the tree fell on the service and they came and yanked the meter, otherwise I would have worked it hot. I called the inspector and told him I had run SEU and had a main breaker outside. No go. He made me either remove the main breaker or run 4-wire. I just put in a standard meter base and left the 3-wire. I still cant get in my head how this seperating nuetrals and grounds works. I know it has to do with a open nuetral putting line voltage on metal parts, but they are still tied together in the meter base. What difference does it make if the service entrance conductors go through a breaker outside?
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
Inside panel is no longer the main so yes must be 4 wire. 4 wires after first disconnect
jetlag
Senior Member
- Location
- Eatonton, Georgia
Yea we had to get it inspected. My neighbor called the power company when the tree fell on the service and they came and yanked the meter, otherwise I would have worked it hot. I called the inspector and told him I had run SEU and had a main breaker outside. No go. He made me either remove the main breaker or run 4-wire. I just put in a standard meter base and left the 3-wire. I still cant get in my head how this seperating nuetrals and grounds works. I know it has to do with a open nuetral putting line voltage on metal parts, but they are still tied together in the meter base. What difference does it make if the service entrance conductors go through a breaker outside?
Well in your case where he let you use the seu it is not any more safe either way , but after the disconnect the inside panel is considered a sub panel and requires 4 wire , you can mount a main panel outside right by the disconnect and still have to 4 wire it. When the current in the neutral gets outside where it joins the ground system it is not likely to go back inside by way of the GEC . Thats what the old timers called the current backing up on you. When they allowed the long seu runs to other end of house metal enclosers could shock you sometimes if you touched something grounded at the same time because there was lot of resistance for the neural current to push its way thru the long ground wire to the outside ground .
jetlag
Senior Member
- Location
- Eatonton, Georgia
when I said not any more safe I meant seu with or without a disconnect. Once you go to 4 wire it is safer because there is no neutral current on the metal inside panel.
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