250.24(C) Grounded Conductor Brought to Service Equipment

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wwhitney

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250.24 and 250.25 actually allow bonding of the neutral ahead of the disconnect so the trough could be the bonding point.
How's that? (2017) 240.25(B) requires a MBJ in each service disconnecting means. I wouldn't think Exception 1 would apply to a field assembly consisting of a trough and multiple service panels.

Cheers, Wayne
 

kwired

Electron manager
Location
NE Nebraska
How's that? (2017) 240.25(B) requires a MBJ in each service disconnecting means. I wouldn't think Exception 1 would apply to a field assembly consisting of a trough and multiple service panels.

Cheers, Wayne
It doesn't, it is basically talking about a switchboard or panelboard with more than one service disconnect within, which has more limitations beginning in 2020 than it used to and you will be seeing more trough and multiple service panels that are field assembled with that change, but a grounded conductor needs to go to each and every disconnect and be bonded there.
 

BradPV

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North Carolina
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Residential PV Qualifier
See 230.2. I don't see any allowance there for a second service for this application. Also see 230.40 EX #5.
Keep reading, 230.2(A)(5) there are considerations for a second service for solar.
Good luck with that one. We maintain a document of many pages which lines out the special requirements of all the AHJs' territories we operate in. The N-G bonding in the disco yes or no is just one of many differences we encounter. It's a pain.
Yes, we keep a database on jurisdictions as well, it is painful but the less that act different the better off we are. They hopefully become the exception....
How's that? (2017) 240.25(B) requires a MBJ in each service disconnecting means. I wouldn't think Exception 1 would apply to a field assembly consisting of a trough and multiple service panels.

Cheers, Wayne
Wayne (2020&17) 250.24(A)(1) specifically states any accessible location and the "enhanced content" has drawings noting some of those locations. I think you meant 250 instead of 240, 250.25(B) enhanced content actually shows the bonding in a trough.....

I do have the NEC code books but as I am in front of a computer quite a bit I like to use the NFPA Link with the expandable enhanced content since I am a visual person....I also hope to never offend anyone in this forum I am truly here to be sharpened by the iron that you gentlemen are and I know I am not always right.....
 

jaggedben

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Northern California
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Solar and Energy Storage Installer
If there is only one connection to utility owned wires then there's only one service.
(Not that it affects anything else under discussion.)
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Wayne (2020&17) 250.24(A)(1) specifically states any accessible location and the "enhanced content" has drawings noting some of those locations.
250.24(A) is about the GEC connection and has nothing to do with bonding or MBJ requirements.

I think you meant 250 instead of 240, 250.25(B) enhanced content actually shows the bonding in a trough.....
A trough ahead of service discos is more or less required to be bonded to the neutral per 250.92. But I can't see how the language of 250.24(B) allows the MBJ to be anywhere other than inside the 'service-disconnect enclosure'. So the enclosure is required to be bonded in both places. One might say that, for the NEC, this is unusually clear and explicit.
 
If there is only one connection to utility owned wires then there's only one service.
(Not that it affects anything else under discussion.)
I agree. Ok I admit I missed 230.2(A)(5) as mentioned by Wayne and Brad, but irregardless (not a word) its rather absurd to have a service point, a set of customer owned conductors after that point, then a split/tap/splice of some sort, and then to claim you have two services. Lol no.
 

wwhitney

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Location
Berkeley, CA
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Retired
I agree. Ok I admit I missed 230.2(A)(5) as mentioned by Wayne and Brad, but irregardless (not a word) its rather absurd to have a service point, a set of customer owned conductors after that point, then a split/tap/splice of some sort, and then to claim you have two services. Lol no.
Well, as far as the rules for how those two service disconnects are configured, does it make any difference whether it's two services (two service points) or one service and two sets of service entrance conductors? Probably at most a little (I haven't poured over 230). So thinking about it as two services could be a useful abstraction, even if there is only one service point.

Cheers, Wayne
 

jaggedben

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Location
Northern California
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Solar and Energy Storage Installer
Well, as far as the rules for how those two service disconnects are configured, does it make any difference whether it's two services (two service points) or one service and two sets of service entrance conductors? Probably at most a little (I haven't poured over 230). So thinking about it as two services could be a useful abstraction, even if there is only one service point.

Cheers, Wayne
Well, with respect to the discussion here, if it's actually two services, you most definitely can not omit an MBJ in one of them. Because you don't know for sure if the utility is supplying the grounded conductors from the same system, nor are they obligated to.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Well, with respect to the discussion here, if it's actually two services, you most definitely can not omit an MBJ in one of them.
Yes, to my knowledge that's never been an option for 2 services or 2 sets of service entrance conductors, only for pre-2020 NEC PV supply side connections, depending on interpretation. And my question was about 2 services vs 2 sets of SECs, no so much the PV supply side options.

I guess the negative effect of omitting 1 of 2 MBJs on 2 services has a chance of being worse than on 2 sets of SECs. With 2 sets of SECs, you'd have to omit both MBJs to end up with no fault clearing path, as the two neutrals are obviously interconnected. With 2 services, you might get 2 neutrals that have no continuity between them on the utility side, and so if you omitted 1 MBJ and 1 GEC connection, you could end up with no fault clearing path.

Cheers, Wayne
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
With 2 service disconnects on the same service one could still end up with no fault clearing path if you fail to provide either an MBJ or another fault clearing path at each disco. But yes, with two services I'd say it has a chance of being even worse. Like, you install a good bonding path between them but it still may not clear a fault.
 

kwired

Electron manager
Location
NE Nebraska
Well, as far as the rules for how those two service disconnects are configured, does it make any difference whether it's two services (two service points) or one service and two sets of service entrance conductors? Probably at most a little (I haven't poured over 230). So thinking about it as two services could be a useful abstraction, even if there is only one service point.

Cheers, Wayne
If supplied from one drop or lateral (or overhead or underground service conductors), then 230.40 basically says it is one service.

If one service all disconnecting means must be grouped in one location. Multiple services do not need to have disconnects grouped together, but all the disconnects of each individual service allowed must be grouped together. Fire pump service disconnect(s) are the one situation where they must not be grouped with the regular service disconnecting means though.
 
If supplied from one drop or lateral (or overhead or underground service conductors), then 230.40 basically says it is one service.

If one service all disconnecting means must be grouped in one location. Multiple services do not need to have disconnects grouped together, but all the disconnects of each individual service allowed must be grouped together. Fire pump service disconnect(s) are the one situation where they must not be grouped with the regular service disconnecting means
Not exactly. See also 230.40 exceptions 1 and 3. One service with non grouped disconnects.
 

kwired

Electron manager
Location
NE Nebraska
Not exactly. See also 230.40 exceptions 1 and 3. One service with non grouped disconnects.
Exception 1 still basically requires one drop or lateral to supply one to six disconnects that are grouped in one location, it does permit multiple such drops or laterals to supply said multi-occupant building. Most the time such buildings are constructed with fire walls and are sort of separate buildings in many ways because of how they are constructed.
 
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