400A parallel service grounding and bonding Residential

[Silverado212]

First residential parallel feed. Existing service is 200A and the home owners are building a rather large addition to existing home. We are adding a second 200A panel in the addition. Will be installing parallel feeders 4/0 alum from pole underground to 320A meter can then to two separate 200A panels. My question is exactly how bonding and grounding will be installed. The existing panel has a GES consisting of GEC to GE (ground rod) and GEC to water pipe?

Thanks

 

[augie47]

Easiest approach, though not the only one, might be to duplicate the 1st with your added panel.

 

[suemarkp]

Is there any disconnect other than the two 200A panels? If not, are those panels side by side (or whatever the NEC menas by "grouped")?

The grounding is easy one you realize you need either a central disconnect or you have the two panels grouped side by side. You have a few different ways to ground -- use a #2 from the meterbase (if allowed by poco) and one large neutral, use a #2 from a gutter of some other common box under or over both panels where you also have a single large neutral, or run a #4 from each disconnect panel to the ground electrode system.

Same choices for the water bond -- a single #2 from a large enough common neutral, or two #4's with one coming frmo each disconnect panel.

 

[Dennis Alwon]

I would install the grounding electrode conductor's in the meter can if they allow it.

 

[gndrod]

COMPLIANCE

COMPLIANCE

Landing GEC in meter can access, per [250.68(A)]

 

[Dennis Alwon]

Landing GEC in meter can access, per [250.68(A)]

I realize that some area say it is not accessible but it is just as accessible as overcurrent protective device with locks on the panel. If that were a problem then the service conductors wouldn't be accessible either-- all splices and termination should be accessible. IMO, that call by an ahj is just wrong.

If power company won't allow that is a different story but I have no idea why they wont allow it. There is a reason those terminals are there in a meter base.

 

[hurk27]

First residential parallel feed. Existing service is 200A and the home owners are building a rather large addition to existing home. We are adding a second 200A panel in the addition. Will be installing parallel feeders 4/0 alum from pole underground to 320A meter can then to two separate 200A panels. My question is exactly how bonding and grounding will be installed. The existing panel has a GES consisting of GEC to GE (ground rod) and GEC to water pipe?

Thanks

You have a few code things you will have to keep in mind, 230.72 is one that was mentioned as it requires the grouping of the main disconnect, if it was planed it install this new panel in the new addition then you will have to install a disconnect near the existing service panel or install two new disconnects at the meter, since these new disconnect will be your new service disconnect then the GEC's can land in them or if allowed in the meter, also if you chose to install a disconnect for the existing service keep in mind that the existing panel now becomes a sub-panel and separation of grounds and neutrals will have to be done as well as the main bonding jumper removed.

also check with them to see if they plan to have a whole house generator installed maybe at a later date, as planing for it now can make your life a whole lot easier now while you have the service apart then trying to do it after this work is done, also makes a good up-sale for a job.

 

[gndrod]

Locks

Locks

I realize that some area say it is not accessible but it is just as accessible as overcurrent protective device with locks on the panel. If that were a problem then the service conductors wouldn't be accessible either-- all splices and termination should be accessible. IMO, that call by an ahj is just wrong.

If power company won't allow that is a different story but I have no idea why they wont allow it. There is a reason those terminals are there in a meter base.

Hi Dennis,

I agree. With the new digital meters, I notice the locks on the meter may not allow removing the service box cover.

 

[meternerd]

Ours happens to be one of the POCO's that do not allow any ground connections in a sealable section (with the exception of bonding jumpers). Our standard says "Customer wiring shall not pass through or terminate in a sealable section". That includes the GEC. The exception is when there are more than 6 disconnects, since the requirement for a main breaker ahead of the service disconnects means the main breaker will be sealed, because it's unmetered, but Code says the neutral/ground bonding must be in the "service disconnect enclosure". Combination meter panels have a barrier between the utility side and the customer side, so once the service conductors leave the sealed side, it then becomes the responsibility of the local AHJ.

The reason we have this requirement is because we consider the GEC connection to be under customer control, and we see a seal as making the connection inaccessible. Our neutral is never grounded ahead of the service disconnect, except at the transformer.

I realize that some area say it is not accessible but it is just as accessible as overcurrent protective device with locks on the panel. If that were a problem then the service conductors wouldn't be accessible either-- all splices and termination should be accessible. IMO, that call by an ahj is just wrong.

If power company won't allow that is a different story but I have no idea why they wont allow it. There is a reason those terminals are there in a meter base.

 

[kwired]

Our standard says "Customer wiring shall not pass through or terminate in a sealable section". That includes the GEC.

Poor way of wording it IMO. Aren't the outgoing service conductors just as much the customers wiring as a GEC? I promise you customer probably paid for them.

Often the customer owns the meter socket and even the mast (if overhead service). The only thing that actually belongs to POCO is the meter that is plugged in.

 

[meternerd]

Yup... the customer owns the meter panel and the service mast (overhead), but the utility still has a right to control access to unmetered conductors. Now think about it....if you were going to try to get free power, would it make sense to tamper with the wiring downstream of the meter? Obviously not. Tampering with the meter itself is nowadays not a viable option, since all newer meters have tamper deterrent features. Makes sense to me for the POCO to secure any unmetered section, regardless of who owns it. But hey, what do I know?

Poor way of wording it IMO. Aren't the outgoing service conductors just as much the customers wiring as a GEC? I promise you customer probably paid for them.

Often the customer owns the meter socket and even the mast (if overhead service). The only thing that actually belongs to POCO is the meter that is plugged in.

 

[kwired]

Yup... the customer owns the meter panel and the service mast (overhead), but the utility still has a right to control access to unmetered conductors. Now think about it....if you were going to try to get free power, would it make sense to tamper with the wiring downstream of the meter? Obviously not. Tampering with the meter itself is nowadays not a viable option, since all newer meters have tamper deterrent features. Makes sense to me for the POCO to secure any unmetered section, regardless of who owns it. But hey, what do I know?

But since customer owns it, POCO should be required to allow them access to it whenever they desire, but still have the right to ensure there is no theft of services. So if I want to pull my meter at 3:00 AM and make changes to my equipment I should be able to do so, with no resistance from the POCO, right? All they need to do is ensure that all power used flows through their meter which is in my socket. Unfortunately most POCO don't see it this way.

 

[GoldDigger]

All they need to do is ensure that all power used flows through their meter which is in my socket.

And just how are they going to ensure this if you can pull their meter and insert your jumpers in your socket?
(With a smart meter, at least they would know that you have pulled it...)

 

[Hv&Lv]

(With a smart meter, at least they would know that you have pulled it...)

Probably not, unless you had it out at the exact time it read. Most, if any aren't constantly read. I tell some to make sure the meter is in at midnight, that is when we read.

 

[kwired]

And just how are they going to ensure this if you can pull their meter and insert your jumpers in your socket?
(With a smart meter, at least they would know that you have pulled it...)

That is what their seal is for. I never said they have no right to ensure there is no theft of service, just that the customer has a right to access his equipment. If they want to lock or seal it then they pretty much need to unlock it at owners demand.

HV&LV is right AFAIK, not many meters are constantly in communication with the central system. Some may periodically send a signal as a maintenance signal, and if a particular meter doesn't send a scheduled signal it may automatically dispatch a technician to check why it didn't respond. This signal maybe only happens a couple times a day and is not necessarily in constant communication with the central system. This can be helpful to helping determine what areas are all effected during an outage and help pinpoint where the problem is before workers even get to the affected area.

 

[Hv&Lv]

This signal maybe only happens a couple times a day and is not necessarily in constant communication with the central system. This can be helpful to helping determine what areas are all effected during an outage and help pinpoint where the problem is before workers even get to the affected area.

There is where the payback will be as far as running trouble. We have cut our runarounds to none since installing these meters.
customers would have to call in if they were out of power, and we may have to go back to an area two or three times a night when they called. Now we ping the meters to know they are ALL on before we leave to go to another area.

 

[Cavie]

Is there any disconnect other than the two 200A panels? If not, are those panels side by side (or whatever the NEC menas by "grouped")?

The grounding is easy one you realize you need either a central disconnect or you have the two panels grouped side by side. You have a few different ways to ground -- use a #2 from the meterbase (if allowed by poco) and one large neutral, use a #2 from a gutter of some other common box under or over both panels where you also have a single large neutral, or run a #4 from each disconnect panel to the ground electrode system.

Same choices for the water bond -- a single #2 from a large enough common neutral, or two #4's with one coming frmo each disconnect panel.

Only 2 ground rods needed, driven 6' apart, and connected to one panel neutral with #6 cu or #4 al. If Ufer is required, no ground rods needed. see 250.66 (A)

 

[Dennis Alwon]

Cavie, the grounding electrode conductor from the ground rods must be connected to both panels I believe not just one.

 

[suemarkp]

I think you could argue that it only needs to go to one if the neutral going to each panel is sized per 250.66 for the whole service (this would be a #2 or 1/0 copper neutral to each panel). The NEC allows the GEC to attach to a common point on the service grounded conductor (at weatherhead, meter, or common gutter). But there are also words that make it sound like it needs to go to each panel if you run it to one of them.

If each panel had a #4 copper neutral (minimum size for a 200A panel), then I think you'd have to run a GEC tap to each panel if the GEC was landed directly in one of them. If each panel has a full service sized 250.66 neutral, then I'm unclear as to whether running to one panel is sufficient (certainly running to one common point outside the disconnets is fine though). Seems like if you can do that, why would you need to run to each disconnect if you chose just one of them.

 

[Cavie]

I think you could argue that it only needs to go to one if the neutral going to each panel is sized per 250.66 for the whole service (this would be a #2 or 1/0 copper neutral to each panel)

. The NEC allows the GEC to attach to a common point on the service grounded conductor (at weatherhead, meter, or common gutter). But there are also words that make it sound like it needs to go to each panel if you run it to one of them.

If each panel had a #4 copper neutral (minimum size for a 200A panel), then I think you'd have to run a GEC tap to each panel if the GEC was landed directly in one of them. If each panel has a full service sized 250.66 neutral, then I'm unclear as to whether running to one panel is sufficient (certainly running to one common point outside the disconnets is fine though). Seems like if you can do that, why would you need to run to each disconnect if you chose just one of them.

This is correct. In the meter, or in either panel, It is still connected to the grounded conductor