Multifamily 43 unit apartment main disconnect question

Location
San mateo, Ca
Occupation
Electrician
Hi guys, this is my first post so bare with me.
I have a building built in 1908 (electrical was installed in the 40's i was told), it has a main disconnect that is rated at 200amp with 2/0 cable going out to feed the unit meters. From the 2/0 there are several10awg cables spliced into it and fed to each meter for each unit. Someone added a meter main to meter the lights and common area receptacles. They basically added a panel that has a 50amp breaker but they just spliced inside the disconnect with polaris with 6awg wire. Is this dangerous? Sinse they parrelled several 10awg wires to the 2/0 i assume its the same concept.
Any code references?
Will try to post pics.
Thanks again,
Nick
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector
FYI From what you describe I don;t think you have parallel conductors as they terminate at different locations.
Nonetheless
As long as there addition load does not exceed the service rating it sounds as if what they installed is compliant. (sight unseen)
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Sounds sketchy, may have been compliant when installed. Probably overloaded today.

Look a at the concept of 'feeder taps'. You have a conductor that is protected at the 'load end' by a circuit breaker or fuse. So you have 200A conductors protected by the 200A main, and then spliced to these you have 30A conductors protected from short circuit by the 200A main and from overload by OCPD somewhere else, possibly in or near the meters.

-Jon
 
Sounds more than sketchy.... if each apartment is getting a 30a 1-pole feed, that's 200/22 = ~9 amps available to each apartment. Sure, demand factors play in, but still- supper time when everyone fires up the microwave, the TV, lights (which probably aren't LED), etc.; I wonder what the demand load really is. I also wonder if that meets San Mateo County's housing codes for minimum facilities.)
 

oldsparky52

Senior Member
Sounds more than sketchy.... if each apartment is getting a 30a 1-pole feed, that's 200/22 = ~9 amps available to each apartment. Sure, demand factors play in, but still- supper time when everyone fires up the microwave, the TV, lights (which probably aren't LED), etc.; I wonder what the demand load really is. I also wonder if that meets San Mateo County's housing codes for minimum facilities.)
Well, if this is from the 40's then 9 amps per apartment might be right (with demand factors) using gas to heat and cook, no such thing as microwaves, so probably a refrigerator and some lights.

Sounds like a rework job.
 

Greentagger

Senior Member
Location
Texas
Occupation
Master Electrician, Electrical Inspector
2/0 is not rated for 200A in this application. 310.15(B)(16). What listed splice termination fitting is being used? Typically split bolts are rated for either 2 or 3 conductors. Run.
 

ramsy

Owner/Operator
Location
LA basin, CA
Occupation
Service Electrician 2017 NEC
2/0 is not rated for 200A in this application. 310.15(B)(16)..
Good Point 1940's Type TW #2/0cu is rated 145A, and requires 150A Main, not 200A.

What listed splice termination fitting is being used? Typically split bolts are rated for either 2 or 3 conductors. Run.
If #2/0 is ~1/2" diameter, a 1/2"-1" OD pipe-bonding clamp may fit an extra 86 #10's mechanically, but IDN if listed for the purpose.

Must also bond 43 meter neutrals somewhere
 

kwired

Electron manager
Location
NE Nebraska
Good Point 1940's Type TW #2/0cu is rated 145A, and requires 150A Main, not 200A.



If #2/0 is ~1/2" diameter, a 1/2"-1" OD pipe-bonding clamp may fit an extra 86 #10's mechanically, but IDN if listed for the purpose.

Must also bond 43 meter neutrals somewhere
Not allowed for 200 amp today either unless is the sole supply to an individual dwelling unit.
 
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