I have a job where a one family dwelling with a good 100 amp service is exsisting feed from a overhead drop.The building is being converted to a condex with 2 units and the 2nd unit is going to be a complete new addition to the exsisting one family to make the 2 units.I don't want to disturb the exsisting 100 amp service.I don't think the poco will let me add a new service to the new addition on the other side of the building with the exsisting 100amp service staying on the opposite side which would create 2 service drops to the same building.So I was going to just add another 100amp service with the main in the meter can right beside the exsisting service and run a SER feeder through the exsisting unit to a sub panel in the new unit. Would this be a violation of 230.72 that says the disconnects shall be grouped?

Assuming your load calc's are done for this additional load. You may be required to add a "house meter" in this conversion, and still only have one service drop or connections from the POCO. (230.2) So why not a 3 meter/main base, and sub all the circuits? Otherwise its a grounding/bonding PITA! Why attempt to keep the original?

e57...the exsisting 100 amp service is in great condition,so I want to leave it as is and add another meter with main for the other side being added.There is no need for a house meter with just 2 units.It will be less money to add just the 1 service as compared to changing the whole thing to a 2 meter/main with sub feeders.My question is if the disconnects being not grouped by having the exsisting one in the basement and the new one in the meter/main outside being in violation of 230.72

Yes, it would be a violation of the grouping rule.
Are you sure you can't have two service drops? If the other condo is separated from the first by a firewall, you have 2 buildings in one structure, and a separate service on the other half would be permitted.

I believe that, despite firewalling, for a 2-unit structure the D/C's should be in one location.

Usually single drop and D/C exemptions are only allowed on really BIG structures (5K+ ft2 each) serving different occupants in our area.

The 2 meter/main to 2 subpanels is probably going to be your answer. Hopefully you can convert the existing panel without too much trouble.

[This message has been edited by DougW (edited 08-28-2004).]

The firewall rule has been around for years. Take a look at some duplex "row houses". They have firewalls between each unit, and service drops one to each, all in a row down the street.
They are just as safe as dropping services to single family homes. If one should happen to burn to the ground, the others will remain standing, and will be occupiable, as the electric service hasn't been damaged because it was attached to the part that burned. In that regard separate services are preferred.

I believe you... and I understand the safety aspect with the firewall.

(I missed the part about it being an entirely new addition. Oops.)

It's just that I've just never seen it in my area. They try to minimize the OH's wherever they can. Different AHJ, different local Code, and different interpretation, no doubt.