Hello,

I'm replacing my exterior main panel with an exterior main disconnect
serving an interior subpanel, so I have a couple questions on
grounding at a residential electrical service entrance.

First, is it OK to run Grounding Electrode Conductor(s) inside the
same 2" PVC conduit as the #1/0 Al SER cable feeding my subpanel? Or
do they need to be separated? I have one conductor from a Ufer
ground, and another conductor going to the copper water service and a
ground rod.

Second, I understand the telephone and cable services need to be
grounded. They presently have individual little ground rods, so I
assume it would be better to interconnect them with the electrical
service grounding system. Is it better to do this inside the
electrical service entrance (at the ground/neutral bar), or outside it
(at the closest Grounding Electrode Conductor)?

Thanks,
Wayne

In article , Wayne Whitney wrote:
Hello,

I'm replacing my exterior main panel with an exterior main disconnect
serving an interior subpanel, so I have a couple questions on
grounding at a residential electrical service entrance.

First, is it OK to run Grounding Electrode Conductor(s) inside the
same 2" PVC conduit as the #1/0 Al SER cable feeding my subpanel? Or
do they need to be separated?

It is a Code requirement that they be run in the same conduit.

Sorry, don't know the answer to your other question.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

On 2007-04-24, Doug Miller wrote:

In article , Wayne Whitney wrote:

First, is it OK to run Grounding Electrode Conductor(s) inside the
same 2" PVC conduit as the #1/0 Al SER cable feeding my subpanel?
Or do they need to be separated?

It is a Code requirement that they be run in the same conduit.

Could you provide a reference? I'm aware of the code requirement that
the Equipment Grounding Conductor for a feeder be run in the same
conduit as the current carrying conductors, but I'm not talking about
the Equipment Grounding Conductor.

Thanks, Wayne

In article , Wayne Whitney wrote:
On 2007-04-24, Doug Miller wrote:

In article , Wayne Whitney
wrote:

First, is it OK to run Grounding Electrode Conductor(s) inside the
same 2" PVC conduit as the #1/0 Al SER cable feeding my subpanel?
Or do they need to be separated?

It is a Code requirement that they be run in the same conduit.

Could you provide a reference? I'm aware of the code requirement that
the Equipment Grounding Conductor for a feeder be run in the same
conduit as the current carrying conductors, but I'm not talking about
the Equipment Grounding Conductor.

Of course you are -- it's the conductor that grounds the subpanel.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Your grounding electrode conductors go the main disconnect, not to the sub
panel



"Wayne Whitney" wrote in message
...
Hello,

I'm replacing my exterior main panel with an exterior main disconnect
serving an interior subpanel, so I have a couple questions on
grounding at a residential electrical service entrance.

First, is it OK to run Grounding Electrode Conductor(s) inside the
same 2" PVC conduit as the #1/0 Al SER cable feeding my subpanel? Or
do they need to be separated? I have one conductor from a Ufer
ground, and another conductor going to the copper water service and a
ground rod.

Second, I understand the telephone and cable services need to be
grounded. They presently have individual little ground rods, so I
assume it would be better to interconnect them with the electrical
service grounding system. Is it better to do this inside the
electrical service entrance (at the ground/neutral bar), or outside it
(at the closest Grounding Electrode Conductor)?

Thanks,
Wayne

On 2007-04-24, Doug Miller wrote:

Wayne Whitney wrote:

First, is it OK to run Grounding Electrode Conductor(s) inside the
same 2" PVC conduit as the #1/0 Al SER cable feeding my subpanel?
Or do they need to be separated?

It is a Code requirement that they be run in the same conduit.

Could you provide a reference? I'm aware of the code requirement that
the Equipment Grounding Conductor for a feeder be run in the same
conduit as the current carrying conductors, but I'm not talking about
the Equipment Grounding Conductor.

Of course you are -- it's the conductor that grounds the subpanel.

No, I'm not, the SER cable already has 4 wires, including an EGC.
[This is in contrast to type SE cable, which only has 3 wires, no
EGC.] These obviously will all be run together, as the NEC requires.

I'm talking about the Grounding Electrode Conductor, which is a
separate wire that runs from the neutral/ground bar in the service
entrance to the earthing sources: Ufer ground, metallic cold water
pipe, and ground rod. Is it OK to run this conductor in the same
conduit as the feeder to my subpanel?

Cheers, Wayne

On 2007-04-24, RBM wrote:

Your grounding electrode conductors go the main disconnect, not to
the sub panel

Yes, of course. I see that I haven't been clear about the geometry,
so my question was unclear. Sorry about that, let me try again:

The main disconnect is on the exterior of the house, and I'll be using
a short section of PVC conduit to connect the main disconnect to the
crawl space, to provide physical protection to the wiring. Both the
grounding electrode conductors and the subpanel feeder need to go
through the crawl space. Can I run them together in the same conduit
stub, or do I need to keep them separate?

Thanks, Wayne

If I'm reading you correctly, I'd just use #4 copper for the grounding
electrode conductors, which don't need supplemental protection, and run them
along side the conduit through the crawlspace


"Wayne Whitney" wrote in message
...
On 2007-04-24, RBM wrote:

Your grounding electrode conductors go the main disconnect, not to
the sub panel

Yes, of course. I see that I haven't been clear about the geometry,
so my question was unclear. Sorry about that, let me try again:

The main disconnect is on the exterior of the house, and I'll be using
a short section of PVC conduit to connect the main disconnect to the
crawl space, to provide physical protection to the wiring. Both the
grounding electrode conductors and the subpanel feeder need to go
through the crawl space. Can I run them together in the same conduit
stub, or do I need to keep them separate?

Thanks, Wayne

In article , Wayne Whitney wrote:

No, I'm not, the SER cable already has 4 wires, including an EGC.
[This is in contrast to type SE cable, which only has 3 wires, no
EGC.] These obviously will all be run together, as the NEC requires.

I'm talking about the Grounding Electrode Conductor, which is a
separate wire that runs from the neutral/ground bar in the service
entrance to the earthing sources: Ufer ground, metallic cold water
pipe, and ground rod. Is it OK to run this conductor in the same
conduit as the feeder to my subpanel?

OK, gotcha now. I'm not aware of anything prohibiting that, but I still
wouldn't do it: if you run it inside the conduit, then you wind up bringing it
into your subpanel, then out again, which is kind of a PITA. Better IMO to use
a grounding electrode large enough (4AWG?) to not require conduit, then run it
separate.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

On 2007-04-24, Doug Miller wrote:

I'm talking about the Grounding Electrode Conductor, which is a
separate wire that runs from the neutral/ground bar in the service
entrance to the earthing sources: Ufer ground, metallic cold water
pipe, and ground rod. Is it OK to run this conductor in the same
conduit as the feeder to my subpanel?

OK, gotcha now. I'm not aware of anything prohibiting that, but I still
wouldn't do it: if you run it inside the conduit, then you wind up bringing it
into your subpanel, then out again, which is kind of a PITA. Better IMO to use
a grounding electrode large enough (4AWG?) to not require conduit, then run it
separate.

The conduit is just a stub to protect the exterior portion of the
wiring, so it's no extra distance to take the GEC through the conduit.
It's primarily a cosmetic issue, to have fewer wires visible on the
side of the house, since the main disconnect is near the front entry.
If there's nothing wrong electrically or code-wise with doing it, I'll
go ahead.

Thanks,
Wayne

On 2007-04-24, RBM wrote:

If I'm reading you correctly, I'd just use #4 copper for the
grounding electrode conductors, which don't need supplemental
protection, and run them along side the conduit through the
crawlspace

That would work fine, but the exterior portion is right near the front
entry, so it becomes a cosmetic issue. Is there anything wrong with
running the GEC through the exterior conduit stub (with the feeder)
instead of alongside it? In the crawl space there's no conduit, just
the SER cable and the bare GECs.

Cheers, Wayne

I think Doug and I are seeing this the same way, which is that this conduit
is attached to either or both the sub panel and the main disconnect, which
would make it a PITA to enter and exit the enclosure. It sounds like this
is merely a sleeve, which wouldn't be attached at either end. In this case I
don't see any reason not to run them through together



"Wayne Whitney" wrote in message
...
On 2007-04-24, RBM wrote:

If I'm reading you correctly, I'd just use #4 copper for the
grounding electrode conductors, which don't need supplemental
protection, and run them along side the conduit through the
crawlspace

That would work fine, but the exterior portion is right near the front
entry, so it becomes a cosmetic issue. Is there anything wrong with
running the GEC through the exterior conduit stub (with the feeder)
instead of alongside it? In the crawl space there's no conduit, just
the SER cable and the bare GECs.

Cheers, Wayne

On 2007-04-24, RBM wrote:

I think Doug and I are seeing this the same way, which is that this
conduit is attached to either or both the sub panel and the main
disconnect, which would make it a PITA to enter and exit the
enclosure.

It is a stub attached at one end to the main disconnect and open at
the other end to the crawl space. So I'll keep in mind it might be a
PITA to enter the enclosure. But 2" PVC should be adequate for the 4
#1/0 subfeeder conductors and the 2 #6 GECs, and the run will only be
a few feet long plus a type LB conduit body.

Thanks to you and Doug for your help with this, I appreciate it.

Cheers, Wayne

In article , "RBM" rbm2(remove wrote:
I think Doug and I are seeing this the same way, which is that this conduit
is attached to either or both the sub panel and the main disconnect, which
would make it a PITA to enter and exit the enclosure. It sounds like this
is merely a sleeve, which wouldn't be attached at either end. In this case I
don't see any reason not to run them through together

Yep - concur.



"Wayne Whitney" wrote in message
...
On 2007-04-24, RBM wrote:

If I'm reading you correctly, I'd just use #4 copper for the
grounding electrode conductors, which don't need supplemental
protection, and run them along side the conduit through the
crawlspace

That would work fine, but the exterior portion is right near the front
entry, so it becomes a cosmetic issue. Is there anything wrong with
running the GEC through the exterior conduit stub (with the feeder)
instead of alongside it? In the crawl space there's no conduit, just
the SER cable and the bare GECs.

Cheers, Wayne



--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

On 2007-04-25, wrote:

The GEC is actually a transmission line, designed to handle high
frequency transients. An ungrounded metal conduit will act as a
choke and slow down the sheadding of this transient. The raceway may
actually carry more of the transient than the conductor. That is why
you see "city" hubs connecting the raceway to a ground rod.

Indeed, that is why I am going to be using PVC conduit.

Cheers, Wayne

According to Wayne Whitney :

I'm talking about the Grounding Electrode Conductor, which is a
separate wire that runs from the neutral/ground bar in the service
entrance to the earthing sources: Ufer ground, metallic cold water
pipe, and ground rod. Is it OK to run this conductor in the same
conduit as the feeder to my subpanel?

An electrician may correct me, but I believe that when the disconnect
is separate from the main panel, and you interconnect the neutral to
the grounding electrode in the disconnect, the main panel is treated
as a subpanel for the purposes of grounding.

Your (one) ground-neutral interconnect is done in the disconnect box,
and the bare wire from disconnect to panel is _not_ an GEC. Also
implying you break the neutral ground interconnect in the panel.

If on the other hand, you want to run the GEC to the panel (which
I believe is more often the case), the neutral-ground interconnect
isn't disconnected, and the bare wire (or metal conduit) going back
from the panel to the disconnect box still isn't an GEC.

The only time you'd run an GEC within conduit from the disconnect to
panel is when it enters one, and interconnects to the neutral at the
other. I'm not sure that's allowed, nor would you want to.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

According to Wayne Whitney :
On 2007-04-25, Chris Lewis wrote:

According to Wayne Whitney :

I'm talking about the Grounding Electrode Conductor, which is a
separate wire that runs from the neutral/ground bar in the service
entrance to the earthing sources: Ufer ground, metallic cold water
pipe, and ground rod. Is it OK to run this conductor in the same
conduit as the feeder to my subpanel?

An electrician may correct me, but I believe that when the disconnect
is separate from the main panel, and you interconnect the neutral to
the grounding electrode in the disconnect, the main panel is treated
as a subpanel for the purposes of grounding.

Yes, that's what I plan to do. My original post was unclear because I
used the term "conduit" for a short stub leading from the crawl space
to the exterior main disconnect, not a full run between the main
disonnect and the subpanel. So my subpanel feeder and my GECs will
share the conduit stub for only a few feet before diverging to their
separate destinations.

I take it then that the GEC is going from the disconnect, thru the
stub (actually a PVC protective sleeve) and thence to the electrodes,
and _not_ following the cables to the panel?

I don't think there's a problem with that. I thought you were
running the GEC to the panel. But you're not, you're running an
ordinary (but large! ;-) grounding wire.

BTW, this raises another question. My disconnect and my subpanel are
30 feet apart. So the only ground/neutral interconnect is at the
disconnect, and the feeder for the subpanel is 4 conductors (#1/0 Al
SER since my service conductors are #2 Cu). At the main disconnect I
have a Ufer ground, a metallic water service pipe, and a driven ground
rod, all connected to the ground/neutral bus bar.

[Remember that the ground and neutral in the SER should _not_ be
interconnected in the panel.]

However, at the subpanel there is available another Ufer ground. That
is, a separate 20' length of #4 copper that is embedded in the lowest
part of the concrete foundation and hopefully tied to the rebar. In
theory this Ufer ground is interconnected with the main disconnect
Ufer ground via the network of rebar in the foundation. Is it both
useful and code-approved to attach this second Ufer to the ground bar
in the subpanel? To complicate things further, the second Ufer is
farther below grade than the first Ufer, as the subpanel is in a
basement while the disconnect abuts a crawl space.

I'd ask an inspector about that. If there's no neutral-ground
connection in the panel (there shouldn't be), you're theoretically
just making the grounding electrode system bigger, but there are
some things about "uninterrupted" connections between grounding
electrodes etc, and it's getting to the point where an inspector
might worry about ground loops or corrosion or weally weally
wierd circumstances resulting in a shock or fire hazard.

[I can't think of any easily plausible circumstances, but the
inspector is the right person for a final answer.]
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

On 2007-04-26, Chris Lewis wrote:

I take it then that the GEC is going from the disconnect, thru the
stub (actually a PVC protective sleeve) and thence to the
electrodes, and _not_ following the cables to the panel?

Yes, that's right, it's a protective sleeve. I did find a reference
that suggested that for purposes of lightning strikes, it is better
not to run the GEC parallel with any current carrying conductors. But
I decided that parallelling for a feet is better than having a
separate sleeve.

I'd ask an inspector about that. If there's no neutral-ground
connection in the panel (there shouldn't be), you're theoretically
just making the grounding electrode system bigger.

Right, except that the ground wire in the feeder cable would be doing
double duty as the EGC and as a bonding conductor for the grounding
electrode system. Perhaps that is not allowed.

[I can't think of any easily plausible circumstances, but the
inspector is the right person for a final answer.]

Well, the inspector provides the final answer of what is allowed, but
doesn't necessarily know what the best practices are.

Cheers, Wayne