installer cut off the #4 ground on the SER

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cubgirl

Member
Hi everybody...

I replaced two 2-2-2-4 SER with 2/0-2/0-2/0-4 & 1/0-1/0-1/0-4 to get 125A in each unit for a two-family. The upstairs SER was de-rated for attic heat & length. I have a 2 gang Siemens WP2211RJ gang meter and a 200A panel (P4040B1200CU) back fed with a 125A breaker and a 125A lug panel (P2020L1125CU).

I paid an installer to do this work. He cut the #4 ground off both SER's at the meter end, over my objections, saying they were redundant. He connected the SER neutrals to the grounded neutral from the POCO. The units were energized & everything appears OK. But I'm worried about those cut grounds.

The units are empty and I don't want to get tenants in them until I determine if this setup is safe. In the last two days, I've read a lot about earth ground, equipment ground, bonding, etc.

At first, I thought the following after reading the NEC and looking at the (1st picture) of EGC bonded to neutral:

250.130 Equipment Ground connections at service equipment shall be made as indicated in 250.130(A) or (B).
(A) For Grounded Systems. The connection shall be made by bonding the equipment grounding conductor (i.e., the unsheathed SER ground cable) to the grounded service conductor (i.e., the grounded neutral from utility company) and the grounding electrode conductor (i.e., the earth ground).

since my gang meter is grounded to earth, the EQPT GND on the SER needed to be connected to the grounded service neutral conductor and the bond between the neutral & ground should be removed at each panel.

if the gang meter were not grounded, then the EQPT GND on the SER still should have been attached to earth ground but the bond between the neutral & ground at each panel would remain intact and each individual panel should be connected to an earth ground.

BUT THEN, I saw the 2nd picture on Mike Holt's site of neutral to case connection and read the following:

"At service equipment, the service neutral conductor provides the effective ground-fault current path to the power supply [250.24(C)]; therefore, an equipment grounding conductor isn't required to be installed within PVC conduit containing service entrance conductors [250.142(A)(1) and 352.60 Ex 2]."

So, if the gang meter is service equipment and the installer connected the SER neutral to the grounded neutral from the POCO, is what he did OK?? It looks exactly like the 2nd picture. (My understanding is the service equipment comes bonded from the manufacturer.)

Can somebody shed some light on this for me please? I need to either move on or get this fixed ASAP.

thank you
cubgirl
 

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Smart $

Esteemed Member
The grounded [neutral] conductor is used for bonding (i.e. grounding) on the utility side of each service disconnecting means. Most residential service entrance conductors are run in SEU.


SEU2.png
 

Smart $

Esteemed Member
FWIW, most jurisdictions would not permit you to run service entrance conductors through an attic. To me, that indicates this run would be on the consumer side of a service disconnecting means, and requires an EGC. Theses feeder conductors are typically run in SER, with separate grounded [neutral] conductor and equipment grounding conductor.
 

cubgirl

Member
FWIW, most jurisdictions would not permit you to run service entrance conductors through an attic.
then what are derated feeders? one reason you derate is because of ambient temperature. the lug panel is upstairs & its feeder goes through an attic. the cable was derated for heat.

AHJ already ok'd it but our AHJ is a joke in my opinion...
 

cubgirl

Member
To me, that indicates this run would be on the consumer side of a service disconnecting means, and requires an EGC. Theses feeder conductors are typically run in SER, with separate grounded [neutral] conductor and equipment grounding conductor.
i'm a retired engineer, NOT AN ELECTRICIAN, which is probably obvious, :lol: yuk yuk

but in the neutral to case picture, the SER, going into the service equipment disconnect, does not have a ground. i'm assuming the other end of the SER is connected to load equipment. so the SER is not grounded at the service disconnecting equipment in this case. and according to NEC 250.142, this is OK.

i'm trying to figure out this earth ground, EQPT GND, bonding stuff. from what i gather on the web, there's a lot of confusion on these topics.

thanks
 
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Smart $

Esteemed Member
The picture shows what's called a meter-main. Meters on the right, and service conductors enter on the right. POCO puts a seal on the locking mechanism. There is manufacturer-installed internal bus or wiring connecting the meters to the breakers in the left compartment. The breakers are the service disconnecting means. Anything connected to the load side of those breakers requires a separate grounded [neutral] conductor and equipment grounding conductor. Your installer is wrong.
 

cubgirl

Member
ok, that's what i'm hearing... i take it that the SER is not grounded (except neutral to grounded service neutral) and the SER is also considered on the load side, not the supply side?

with that in mind, i find this in the code:

250.142 Use of Grounded Circuit Conductor for Grounding Equipment

B) Load Side Equipment
Except as permitted in 250.30 (A) (1) and 250.32 (B) a grounded circuit conductor shall not be used for grounding non-current-carrying metal parts of equipment on the load side of the service disconnecting means or on the load side of a separately derived system disconnecting means or the over current devices for a separately derived system not having a main disconnecting means.

Exception No 2) It shall be permissible to ground meter enclosures by connection to the grounded circuit conductor on the load side of the service disconnect if
a) No service ground fault protection is installed and
b) All meter enclosures are located near the service disconnecting means and
c) The size of the grounded circuit conductor is not smaller than the size specified in Table 250 122 for equipment grounding conductors

how do i know exception #2 does not apply to this scenario?

sorry for not "getting it" faster but the code is confusing.
 

cubgirl

Member
ok... yes, i understand but then why doesn't 250.142(A)(1) apply?

250.142 Use of Grounded Circuit Conductor for Grounding Equipment
(A) Supply Side Equipment
A grounded circuit conductor shall be permitted to ground non-current carrying metal parts of equipment raceways and other enclosures at any of the following locations
(1) On the supply side or within the enclosure of the ac service disconnecting means
 

GoldDigger

Moderator
Staff member
ok... yes, i understand but then why doesn't 250.142(A)(1) apply?

250.142 Use of Grounded Circuit Conductor for Grounding Equipment
(A) Supply Side Equipment
A grounded circuit conductor shall be permitted to ground non-current carrying metal parts of equipment raceways and other enclosures at any of the following locations
(1) On the supply side or within the enclosure of the ac service disconnecting means
That AC service disconnecting means is the one at the meter-main enclosure, not the disconnecting means at the subpanel for each unit.
If there were not an AC disconnect next to the meter then the wiring to each unit would be service wiring and could not run inside the building.
The main breaker for the unit disconnects all of that unit's wiring but is not the service disconnect (associated with the first OCPD).
 

cubgirl

Member
That AC service disconnecting means is the one at the meter-main enclosure, not the disconnecting means at the subpanel for each unit.
If there were not an AC disconnect next to the meter then the wiring to each unit would be service wiring and could not run inside the building.
The main breaker for the unit disconnects all of that unit's wiring but is not the service disconnect (associated with the first OCPD).
Hi, well it HAS to be on the supply side or the load side. one or the other...

so are you saying the SER is on load side? also, i didn't want the panels to be sub-panels but actually, i don't care as long as they're wired safely.
 

infinity

Moderator
Staff member
From the load side of the service disconnect(s) (the CB's in the meter section) to the panels you have feeder conductors. An EGC is required with that feeder based on T250.122. Typically that would be the fourth conductor in the SER.
 

GoldDigger

Moderator
Staff member
the meters are the demarcation between supply & load, correct?

if so, then aren't the tenant disconnects in the gang meter considered to be on the load side?
There are three different concepts in play here:

1. POCO wires versus customer wires (NESC rules versus NEC rules among other things.) That demarcation is called the service point. It is often at the meter but may be at the top of the weatherhead for overhead service or where the underground service comes out of the ground. Or any place POCO declares it to be.
2. Metered versus unmetered. NEC does not care about this distinction at all. POCO does care very strongly. This demarcation is always, by definition, at the meter. The meter has a supply side and a load side too, but that does not count for the rule we are looking at.
3. This is the big one: Service conductors versus feeder and branch conductors. This demarcation is always at the first overcurrent protection along the wires from the utility. Since the OCPD is always closely associated with a disconnect, that is called the service disconnect. Any unfused disconnects before or after the meter do not count.
On the POCO side are service conductors, which may also be a service drop or a service lateral but may be customer owned service wires too.

Service wires are NOT allowed to run inside te building except for a locally defined short distance to get to the main (service) disconnect.
You do want to have your service disconnect(s) at the meter because if you don't all of the wires going a distance to the two units must stay entirely outside the building.

What you are using SER for are called feeders, and you have to accept that.
The ground to neutral bond is in the general area of the service disconnect. From there downstream you must have separate wires for the two (neutral and EGC.)
 

kwired

Electron manager
then what are derated feeders? one reason you derate is because of ambient temperature. the lug panel is upstairs & its feeder goes through an attic. the cable was derated for heat.

AHJ already ok'd it but our AHJ is a joke in my opinion...
What he was getting at was the fact that service conductors must hit a service disconnecting means before/at/near the point of entry to a building. Beyond service disconnecting means you must keep separate grounded and equipment grounding conductors. Your installer very likely clipped the EGC that is required to be separate from the grounded conductor in your installation and now you either have no equipment grounding at all or it is improperly done via the grounded conductor.
 

cubgirl

Member
so i'm going to get this fixed ASAP... i've been advised to get a splice box to splice the #4 GND on the SER but that solution bothers me a bit. there is no GND left at the meter end. we could splice it in the middle of the SER (at least the 35' 2/0; the 1/0 would be more difficult as most of it is in conduit) but i'd rather have a non-spliced ground wire.

is a better solution just buying a sheathed #4 and running it separately in parallel to the SER?

here is the schematic of the meter main. my plan is to run #4 to the N2/EQPT GND bus/bar (which is already bonded by the manufacturer, is that right??) and the other end will to the ground bar at the panel.

at each siemens panel (schematics attached), i'm going to ensure the neutral and ground bus/bars are NOT bonded together. they're not bonded at the factory, right? so unless a jumper is installed, i can assume they are not bonded.

taking these steps will fix everything, is that correct? is there anything else i need to know or do??

thanks for your help. i appreciate it very much.
cub
 

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kwired

Electron manager
Seems to me unless the run is really long you are just as well off replacing the cables instead of trying to splice them.
 
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