feeder sizing

Status
Not open for further replies.
rbwsparky

rbwsparky

Senior Member
Location
Sewickley,PA
I recently puchased a commercial building, a dance studio and 3 small 1 bedroom apartments.This building now has 3 seperate service drops. I need to update the whole building electrical system because of frayed cloth cables. My concern is the size of a new SE cable. I have a total calculation of 121 amps. There is no laundry, gas heat and only 1 electric range. The meters are in the basement because of the narrow walkway between this building and the building next door(2 feet). My plan is to install a 200amp disco before a trough feeding 4 100 amp panels. Does this seem like a good plan or am I overlooking something
 
rbwsparky said:
I recently puchased a commercial building, a dance studio and 3 small 1 bedroom apartments.This building now has 3 seperate service drops. I need to update the whole building electrical system because of frayed cloth cables. My concern is the size of a new SE cable. I have a total calculation of 121 amps. There is no laundry, gas heat and only 1 electric range. The meters are in the basement because of the narrow walkway between this building and the building next door(2 feet). My plan is to install a 200amp disco before a trough feeding 4 100 amp panels. Does this seem like a good plan or am I overlooking something
Click to expand...
I thought a laundry must be provided for dwelling units. I guess you must be grandfathered in. Be careful because sometimes when you upgrade you may be required to add laundry. Otherwise I think you are okay with the install.
 
With 210.52(F), You can omit the laundry outlets per dwelling unit if laundry facilities are provided for all occupants (Ex. 1), or if such facilities will not be installed or permitted (Ex. 2).

Still need two (or more) 1500 watt allowances per unit for SABC, plus the other sq ft va and equipment.
 
feeder sizing

I calculated with 3 Small Appl Cuircuts, to account for microwave,I overcompensated for heat also.I also added a few more sq.ft. and all I could increase to was140.3 amps.
 
Last edited:
feeder sizing

Can I use a 4/0 SE AL cable based on table 310.15(B)(6) and 200A disco or do I go to table 310.16
 
Last edited:
If that is three SABC for each apt. and you've accounted for the rest than you might be ok at a 200 amp service. Dont forget the show windows loads, sign circuit(s), and decent lights in the dance studio.

If it will be 200 amp overcurrent for the service, you'll need 3/0 cu. Of course it will be accessible to all occupants.
 
rbwsparky said:
Can I use a 4/0 SE AL cable based on table 310.15(B)(6) and 200A disco or do I go to table 310.16
Click to expand...

You can't use (B)(6), because this is not a single dwelling unit, but from the table 310.16, at 75 deg, 180 amps you can protect the wire at 200 amps 240.4(B). As long as your final calculated load is not over 180.
 
I thought so but I wasn't sure if it could be SE cable or if had to use individual conductors in conduit. Most services around here are SE cable.
 
Volta said:
You can't use (B)(6), because this is not a single dwelling unit, but from the table 310.16, at 75 deg, 180 amps you can protect the wire at 200 amps 240.4(B). As long as your final calculated load is not over 180.
Click to expand...
Just want to clarify that (B)(6) can be used on multifamily dwellings but since there is a non dwelling unit involved I would agree that (B)(6) cannot be used.
 
rbwsparky said:
I thought so but I wasn't sure if it could be SE cable or if had to use individual conductors in conduit. Most services around here are SE cable.
Click to expand...

You may be able to use se cable but I would check with the inspection office as to how they classify the building. You may be able to use NM also.
 
If your final calc gets at all close to your 4/0 ampacity, I would strongly recommend that you upsize to 250 kcm at 205 amps, or 3/0 cu which is rated 200 a. It is just to easy for everyone to plug in space heaters or window a/c units or something some season and push you over the limit of the 4/0.
Better protection.
 
You're right 310.15(B)(6) does read Dwelling Services. My main concern was with 180A from 75C column was 180A and the disco being fused at 200A
 
Dennis Alwon said:
Just want to clarify that (B)(6) can be used on multifamily dwellings but since there is a non dwelling unit involved I would agree that (B)(6) cannot be used.
Click to expand...
True, but only to each individual unit, not a feeder or service suppling more than one.

Dennis Alwon said:
You may be able to use se cable but I would check with the inspection office as to how they classify the building. You may be able to use NM also.
Click to expand...
334.12(A)(3). :-?
 
Volta said:
334.12(A)(3). :-?
Click to expand...

Sorry I was not clear. I was meaning nm may be able to be used in the building.

I was reacting to this post
I thought so but I wasn't sure if it could be SE cable or if had to use individual conductors in conduit. Most services around here are SE cable
Click to expand...
I thought the poster was thinking se could not be used in commercial applications so I was stating that nm or se may be allowed. You are correct the nm may not be used as se conductors.
 
rbwsparky said:
How could that be? Do they even make 4/0 nm
Click to expand...

Nope-- art. 334.104

334.104 Conductors.
The 600-volt insulated conductors shall be sizes 14 AWG through 2 AWG copper conductors or sizes 12 AWG through 2 AWG aluminum or copper-clad aluminum conductors. The communications conductors shall comply with Part V of Article 800.
Click to expand...
 
Status
Not open for further replies.
Top