Dual meter Grounding?

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journeyman0217

Senior Member
Location
philadelphia,pa
I just got a service replacement job for a duplex. there is currently 2 meters on the house, one supplies the first floor which goes to a 200 amp main breaker panel and the other supplies the second floor which goes to a 100amp main breaker panel. does the grounding electrode conductor just need to be ran to the 200amp main breaker panel? My first time working on a duplex so I'd appreciate any advice, thanks in advance!
 

Buck Parrish

Senior Member
Location
NC & IN
As long as they're "grouped" then you're fine.

If the units have separate water lines that are metal underground they will need to be used per 250.53D
 

packersparky

Senior Member
Location
Wisconsin
Occupation
Inspector
As long as they're "grouped" then you're fine.

If the units have separate water lines that are metal underground they will need to be used per 250.53D

For a duplex the disconnects would not have to be grouped. 230.72 states that the disconnects permitted in 230.71(A) shall be grouped. 230.71(A) mentions the exceptions in 230.40. 230.40 Exc. No. 1 allows service entrance conductors be run to each occupancy. The disconnects could be located in each occupancy.
 

kwired

Electron manager
Location
NE Nebraska
You have more than one option on how to do the grounding electrode system here.

Read through 250.64 (in particular sub part (D)).
 

journeyman0217

Senior Member
Location
philadelphia,pa
You have more than one option on how to do the grounding electrode system here.

Read through 250.64 (in particular sub part (D)).

thanks<

The main service line is 4/0 seu rated for 200amps in residential dwelling, homeowner wants to feed 1-200amp main breaker panel and 3-100amp main breaker panels. Is this permitted as long as the calculated load does not exceed 200amps?
 

Buck Parrish

Senior Member
Location
NC & IN
For a duplex the disconnects would not have to be grouped. 230.72 states that the disconnects permitted in 230.71(A) shall be grouped. 230.71(A) mentions the exceptions in 230.40. 230.40 Exc. No. 1 allows service entrance conductors be run to each occupancy. The disconnects could be located in each occupancy.
PHP:
I'm not reading it like that. I have the 14 book
 

kwired

Electron manager
Location
NE Nebraska
thanks<

The main service line is 4/0 seu rated for 200amps in residential dwelling, homeowner wants to feed 1-200amp main breaker panel and 3-100amp main breaker panels. Is this permitted as long as the calculated load does not exceed 200amps?
Yes, you can find this in 230.90(A) exception 3.

Note that for 4/0 aluminum and when feeding other than just one individual dwelling the ampacity of the conductor is only 180 amps and not 200.
 

kwired

Electron manager
Location
NE Nebraska
I'm not reading it like that. I have the 14 book

exception 1 from 2014 NEC says: A building with more than one occupancy shall be permitted to have one set of service-entrance conductors for each service, as defined in 230.2, run to each occupancy or group of occupancies.

How does that not allow one set of service conductors and a service disconnect (actually up to six disconnects when you dig deeper) to each occupancy?
 

journeyman0217

Senior Member
Location
philadelphia,pa
Yes, you can find this in 230.90(A) exception 3.

Note that for 4/0 aluminum and when feeding other than just one individual dwelling the ampacity of the conductor is only 180 amps and not 200.



Ah! Does this mean installing the 200 amp MBP would be a code violation unless I increased the service conductor size?
 

Buck Parrish

Senior Member
Location
NC & IN
exception 1 from 2014 NEC says: A building with more than one occupancy shall be permitted to have one set of service-entrance conductors for each service, as defined in 230.2, run to each occupancy or group of occupancies.

How does that not allow one set of service conductors and a service disconnect (actually up to six disconnects when you dig deeper) to each occupancy?
PHP:

I think you're thinking of if you have separate laterals from the poco,
 

kwired

Electron manager
Location
NE Nebraska
I think you're thinking of if you have separate laterals from the poco,
Ok you are on to something there. Basically you can have a drop or lateral to each occupancy, you can't have one drop or lateral and then run a set of service entrance conductors to each occupancy, would have to group disconnects together and run feeders to each occupancy in that situation.
 

packersparky

Senior Member
Location
Wisconsin
Occupation
Inspector
I think you're thinking of if you have separate laterals from the poco,

No, it's for service entrance conductors. Here is 230.72(A)


(A) General. The two to six disconnects as permitted in
230.71 shall be grouped.

Here is 230.71(A)

(A) General. The service disconnecting means for each
service permitted by 230.2, or for each set of service entrance
conductors permitted by 230.40, Exception No. 1,
3, 4, or 5, shall consist of not more than six switches or sets
of circuit breakers,

Here is 230.40 Exc. No. 1

Exception No. 1: A building with more than one occupancy
shall be permitted to have one set of service entrance
conductors for each service, as defined in 230.2,
run to each occupancy or group of occupancies. If the
number of service disconnect locations for any given classification
of service does not exceed six, the requirements of
230.2(E) shall apply at each location.
 

kwired

Electron manager
Location
NE Nebraska
Ah! Does this mean installing the 200 amp MBP would be a code violation unless I increased the service conductor size?
Unless you are supplying a single dwelling unit with 4/0 (allowed by 310.15(B)(7)), 4/0 aluminum @ 75C is only 180 amp conductor. You can put 200 amp overcurrent protection on it since 180 is not a standard overcurrent device as long as the connected load is not over 180.
 

journeyman0217

Senior Member
Location
philadelphia,pa
Unless you are supplying a single dwelling unit with 4/0 (allowed by 310.15(B)(7)), 4/0 aluminum @ 75C is only 180 amp conductor. You can put 200 amp overcurrent protection on it since 180 is not a standard overcurrent device as long as the connected load is not over 180.


ah thanks alot for the explanation!
 
No, it's for service entrance conductors. Here is 230.72(A)


(A) General. The two to six disconnects as permitted in
230.71 shall be grouped.

Here is 230.71(A)

(A) General. The service disconnecting means for each
service permitted by 230.2, or for each set of service entrance
conductors permitted by 230.40, Exception No. 1,
3, 4, or 5, shall consist of not more than six switches or sets
of circuit breakers,

Here is 230.40 Exc. No. 1

Exception No. 1: A building with more than one occupancy
shall be permitted to have one set of service entrance
conductors for each service, as defined in 230.2,
run to each occupancy or group of occupancies. If the
number of service disconnect locations for any given classification
of service does not exceed six, the requirements of
230.2(E) shall apply at each location.

Packersparky is correct. You can indeed run a set of service entrance conductors to each occupancy, and not have the disconnects grouped - pretty much just like one of the other 230.40 exceptions that allows a set to a detached structure of a dwelling unit.
 
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