400/320 service 1p 120/240

P

pmoney44

Member
Location
MASSACHUSETTS
Good day,
I’m installing a 400 amp service. I should clarify. 400 non continuous 320 continuous.

400 meter socket 320 continuous. I’m only allowed to have the 320 per utility otherwise I need special meter and other stuff. So I’m going 320 at a commercial application.

Meter to fused disconnect. Then load side disconnect to 2 200 amp panels.

I’m getting super frustrated with conductor sizing and fuse size.
Thinking 600 aluminum for line side meter socket (40’) run. 600 load side meter to line side disconnect.

Load side disconnect 250 aluminum dual lug to fee each panel.

400 amp fuses

Voltage 120/240 single phase.
Not sure of my conductor size choice and or fuse choice.

Feel like they only let me get 320 so I should size fuses and conductors ? Obviously they don’t make a 320 fuse so kind of losing my mind here

Please help. Thanks to all!!
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
pmoney44 said:
I’m getting super frustrated with conductor sizing and fuse size.
Thinking 600 aluminum for line side meter socket (40’) run. 600 load side meter to line side disconnect.
Click to expand...
What is your calculated load? 600 kcmil Al is only good for 340 amps.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
not sure exactly of your needs, but typical way to set this is up is two sets on the line side, maybe 2 sets of 4/0 AL. Load side probably skip the single main and use 230.40 exception #2 to each main breaker panel, with 250 or 4/0 AL
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
With a calculated load of 265, and a 400 amp OCPD your 600 kcmil aluminum conductors (340 amps) are too small. With the next size up rule the standard size is 350 amps.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
infinity said:
With a calculated load of 265, and a 400 amp OCPD your 600 kcmil aluminum conductors (340 amps) are too small. With the next size up rule the standard size is 350 amps.
Click to expand...
I know u know this but for the OP, if he uses the two service disconnect approach, then he can size the line side conductors to the load and could use one set of 400AL. That's kinda an odd size around here and special order so I would use 500.
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
electrofelon said:
I know u know this but for the OP, if he uses the two service disconnect approach, then he can size the line side conductors to the load and could use one set of 400AL. That's kinda an odd size around here and special order so I would use 500.
Click to expand...
I agree. For some reason he's chosen to use a 400 amp single main disconnect which changes the conductor sizes.
 
C

Carultch

Senior Member
Location
Massachusetts
pmoney44 said:
400 meter socket 320 continuous. I’m only allowed to have the 320 per utility otherwise I need special meter and other stuff. So I’m going 320 at a commercial application.

Feel like they only let me get 320 so I should size fuses and conductors ? Obviously they don’t make a 320 fuse so kind of losing my mind here
Click to expand...
The meter socket manufacturers consider a slightly different meaning of the amp rating, than the manufacturers of other distribution equipment. This is kind of confusing, and it would be nice to see a white paper addressing the FAQ on these borderline situations, to clarify whether-or-not and why a breaker can exceed the meter socket rating.

Generally speaking, the 320A meter sockets work for most applications where an OCPD up to a 400A breaker would be installed on the same circuit. The meter socket is rated for 320A continuous, which corresponds to 400A after you multiply by the 125% factor. As long as your calculated load isn't more than 320A prior to applying the 125% factor to continuos loads, you're good to use it on a 350A or 400A service.
 
W

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Are there actually any CL320 meter sockets that are marked just "320 Amps Continuous" rather than being marked "400 Amps (320 Amps Continuous)"? Those are the two marking options provided for in UL 414 Section 27.3. (Well, the ratio in the second case can be anything up to 125%, but I'm expecting it's always 125% in practice).

Cheers, Wayne
 
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