First time I have posted anything, but use the forums a lot to find most answers to my questions. I mostly do single family homes, but this one obviously is not. I plan on replacing these meters and panels with a gutter box, and adding 2 meter main 100 amp panels. My question is the sizing of the service entrance conductors. Does it matter what size they are, even if they are not even rated for 100 amps, since I will not be adding any load to the building? As of right now i have no clue what size the wires are, but I want to be prepared. I appreciate all the input I can get. Thank you in advance.
Sizing of service entrance conductors multi meter residential situation
- Thread starter ricksan76
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First time I have posted anything, but use the forums a lot to find most answers to my questions. I mostly do single family homes, but this one obviously is not. I plan on replacing these meters and panels with a gutter box, and adding 2 meter main 100 amp panels. My question is the sizing of the service entrance conductors. Does it matter what size they are, even if they are not even rated for 100 amps, since I will not be adding any load to the building? As of right now i have no clue what size the wires are, but I want to be prepared. I appreciate all the input I can get. Thank you in advance.
IF you have two separate dwelling units and are adding "two meter main" panels and plan to have a separate riser for each then you conductors could be size by 310.15(B)(6) {'08 COde}
If you plan on one riser to feed both meter/panels then you can use Art 220 and calculate the size and use 310.16
If you plan on one riser to feed both meter/panels then you can use Art 220 and calculate the size and use 310.16
My plan was actually to put in a hot gutter box, and place each of the meter main combo units under the gutter box, since all of the circuits are already in place. Right now there is no main breaker in either of these boxes, this is why we are replacing them. I planned on using the same existing wires and mast since there is no load being added. But, if the wires are not rated for at least 100 amps, can a 100 a main breaker even be used? There are only 5 breakers in one panel, and 4 in the other.
230.79 requires a 100 amp minimum service disconnect for a single family dwelling.
As noted above, if you are going to feed both service disconnects with a single riser you can use Art 220 to calculate the load and size accordingly.
Locally in this situation, most E/Cs would size the riser at 200 amps and not worry about the calculation, especially taking future loads into consideration.
As noted above, if you are going to feed both service disconnects with a single riser you can use Art 220 to calculate the load and size accordingly.
Locally in this situation, most E/Cs would size the riser at 200 amps and not worry about the calculation, especially taking future loads into consideration.
conmgt
Senior Member
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- 2 Phase Philly
I wouldn't say simply throwing in a 200A SEC is ever the best way to go but I see it all of the time and its because folks don't want to bother with load calcs.
The best way to go, IMO, is to do a load calc. They are so easy to do and it seems that possibly you haven't much experience doing them.
Again, they are easy and they take so much guess work out of projects.
Do the load calcs and if the current SEC is large enough, leave it alone. If the calc is larger than the current SEC, replace with a new set of conductors to meet that load...100A min. Done.
Get 100A panels but size the main breaker for each panel according to the calcs. Done.
You can get 6 to 16 circuit panels rated 100A that can use a backfed dbl pole breaker for a main but make sure everything reads "suitable for service"
Maybe upsize if the owner is considering adding an addition or a pool/hot tub.
Describe the property. Duplex? How many sf per unit? Gas cooking, heat, hot water? Laundry room? Central air?
The best way to go, IMO, is to do a load calc. They are so easy to do and it seems that possibly you haven't much experience doing them.
Again, they are easy and they take so much guess work out of projects.
Do the load calcs and if the current SEC is large enough, leave it alone. If the calc is larger than the current SEC, replace with a new set of conductors to meet that load...100A min. Done.
Get 100A panels but size the main breaker for each panel according to the calcs. Done.
You can get 6 to 16 circuit panels rated 100A that can use a backfed dbl pole breaker for a main but make sure everything reads "suitable for service"
Maybe upsize if the owner is considering adding an addition or a pool/hot tub.
Describe the property. Duplex? How many sf per unit? Gas cooking, heat, hot water? Laundry room? Central air?
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