Mast service - 1 or 2 risers?

[Kdog76]

I am looking at a service upgrade for a commercial occupancy / apartment unit. Single phase overhead service. Customer would like to see a 200 amp panel in the basement for the shop and a 100 amp outdoor panel for the apartment. This would be a mast service, requiring 2" RMC & a roof penetration. I can price it out as one mast service - using copper 250 mcm's and a 4/0 neutral in one pipe. This way would need a 2 position 200 amp meter base, OR I can price it out as 2 riser pipes, 2 roof penetrations and a much less expensive overhead 100 amp socket & a seperate 200 amp overhead socket next to it.
If I go one riser pipe, it will have to be in copper, If I go two seperate risers, then I could go AL or CU...I know labor is less if I go one riser pipe, and material cost difference doesn't seem to be much, of course AL will be less.
Any thoughts?

 

[A/A Fuel GTX]

If you go with one riser, you'll need 2 1/2" GRC for the wire sizes you referred to. I've seen it done both ways. I think one riser looks a lot nicer.

 

[Kdog76]

Table C.8(A) allows a max of 4 250 mcm's in 2" rmc. The rigid is required by the POCO if it's a thru the soffit / roof penetration. Raises another question, the largest meter hub I've used has been 2". What if I really did need a 2 1/2" riser - do they make such a meter hub for sizes larger then 2"? (And yes I've seen meyer's hubs before)

 

[active1]

If the mast is used to support the service drop you may have to go with a larger RMC pipe per poco or local rules. Nothing funnier than when someone elce has to redo the overhead because the mast was too small for support per local codes or poco. Such as I remember using a 3" RMC for 200a overhead using the mast to support the drop.

 

[chris kennedy]

Table C.8(A) allows a max of 4 250 mcm's in 2" rmc.

Who is going to wrestle them into a 2" weatherhead? Do yourself a favor and use a larger one.

 

[jgarner]

Wouldn't both panels need to be group together per 230.72

 

[220/221]

I generally opt for the two risers in situations like this.

One may look better but two is just easier.

 

[A/A Fuel GTX]

Table C.8(A) allows a max of 4 250 mcm's in 2" rmc.

Table C.8(A) is for compact conductors. I highly doubt you would be using compact conductors for a service but I may be wrong.

 

[Kdog76]

Wouldn't both panels need to be group together per 230.72

Good question. Our AHJ considers that each tenant has to have access to their panel and he will allow a main breaker panel in the basement for one unit, and the other to be placed outside for the other.

Also, our POCO requires a minimum of 2" RMC for overhead mast services.

 

[Kdog76]

Table C.8(A) is for compact conductors. I highly doubt you would be using compact conductors for a service but I may be wrong.

My bad. I should have looked at Table C.8 Which still allows 3 250's in a 2" RMC.

 

[A/A Fuel GTX]

My bad. I should have looked at Table C.8 Which still allows 3 250's in a 2" RMC.

My bad too........I was looking at the RHW column

 

[Kdog76]

The post about bending those 250's in a 2" weatherhead has got me thinking there also...Mogul weatherheads are EXPENSIVE, so is going up the next size larger RMC... SO, now I'm back to thinking two risers again...

 

[Mule]

I am looking at a service upgrade for a commercial occupancy / apartment unit. Single phase overhead service. Customer would like to see a 200 amp panel in the basement for the shop and a 100 amp outdoor panel for the apartment. This would be a mast service, requiring 2" RMC & a roof penetration. I can price it out as one mast service - using copper 250 mcm's and a 4/0 neutral in one pipe. This way would need a 2 position 200 amp meter base, OR I can price it out as 2 riser pipes, 2 roof penetrations and a much less expensive overhead 100 amp socket & a seperate 200 amp overhead socket next to it.
If I go one riser pipe, it will have to be in copper, If I go two seperate risers, then I could go AL or CU...I know labor is less if I go one riser pipe, and material cost difference doesn't seem to be much, of course AL will be less.
Any thoughts?

Im thinking I've run into this before and our poco would not put two services on the same dwelling unless it was a detached garage or different voltages, etc.