I have a detached garage that I have added a feeder panel (sub-panel)
to for extra power. Code required that it was a four wire connection
from the main panel in the house (Two hot, ground, and neutral). Also,
per code the two ground rods were required and the neutral bus was to
NOT be connected to the grounding bar in the subpanel.
Question: (finally) I would like to add a 220v outlet for a dust
collection machine -- easy wiring, only three wires, two hots and a
ground -- does the ground go to the grounding bar? This makes me
nervous as there is not dedicated neutral connection and the neutral
and grounding bars are not bonded -- as they would be in a normal -- in
the house set up.
Great! Thanks for the information. I really want to meet code
requirements -- but the code is a little confusing to me (newby).
I don't have the neutral and grounding bars bounded. And the
grounding bar is connected to the grounding bar in the main panel and
to two grounding rods outside the garage and separated by about 7 feet
(what a workout).
alan wrote:
> On 6 Sep 2006 18:50:02 -0700, [email protected] wrote:
>
> >I have a detached garage that I have added a feeder panel (sub-panel)
> >to for extra power. Code required that it was a four wire connection
> >from the main panel in the house (Two hot, ground, and neutral). Also,
> >per code the two ground rods were required and the neutral bus was to
> >NOT be connected to the grounding bar in the subpanel.
> >
> >Question: (finally) I would like to add a 220v outlet for a dust
> >collection machine -- easy wiring, only three wires, two hots and a
> >ground -- does the ground go to the grounding bar? This makes me
> >nervous as there is not dedicated neutral connection and the neutral
> >and grounding bars are not bonded -- as they would be in a normal -- in
> >the house set up.
>
> Absolutely attach the ground to the ground bar, which should be
> attached to the main (panel) ground and to the ground rod at the
> garage. Do not bond the sub-panel neutral to the ground. That's
> code and correct, whether for a single or two pole circuit.
[email protected] wrote:
> I have a detached garage that I have added a feeder panel (sub-panel)
> to for extra power. Code required that it was a four wire connection
> from the main panel in the house (Two hot, ground, and neutral). Also,
> per code the two ground rods were required and the neutral bus was to
> NOT be connected to the grounding bar in the subpanel.
>
> Question: (finally) I would like to add a 220v outlet for a dust
> collection machine -- easy wiring, only three wires, two hots and a
> ground -- does the ground go to the grounding bar? This makes me
> nervous as there is not dedicated neutral connection and the neutral
> and grounding bars are not bonded -- as they would be in a normal -- in
> the house set up.
>
The ground for the outlet attaches to the ground bus in the sub-panel.
Although not bonded at the sub-panel the neutral and ground buses are
bonded at the main panel (which is why the code requires a four wire
connection between the two panels).
--
Jack Novak
Buffalo, NY - USA
[email protected]
In article <[email protected]>, [email protected] wrote:
>I have a detached garage that I have added a feeder panel (sub-panel)
>to for extra power. Code required that it was a four wire connection
>from the main panel in the house (Two hot, ground, and neutral). Also,
>per code the two ground rods were required and the neutral bus was to
>NOT be connected to the grounding bar in the subpanel.
Yep -- good so far.
>
>Question: (finally) I would like to add a 220v outlet for a dust
>collection machine -- easy wiring, only three wires, two hots and a
>ground -- does the ground go to the grounding bar?
Yes, it does.
>This makes me
>nervous as there is not dedicated neutral connection and the neutral
>and grounding bars are not bonded -- as they would be in a normal -- in
>the house set up.
Why? Nothing to be nervous about. A 220V load doesn't *have* a neutral. It's
just two hots and the equipment (safety) ground. Everything is the way it
should be.
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
[email protected] wrote:
> I have a detached garage that I have added a feeder panel (sub-panel)
> to for extra power. Code required that it was a four wire connection
> from the main panel in the house (Two hot, ground, and neutral). Also,
> per code the two ground rods were required and the neutral bus was to
> NOT be connected to the grounding bar in the subpanel.
Good.
> Question: (finally) I would like to add a 220v outlet for a dust
> collection machine -- easy wiring, only three wires, two hots and a
> ground -- does the ground go to the grounding bar? This makes me
> nervous as there is not dedicated neutral connection and the neutral
> and grounding bars are not bonded -- as they would be in a normal -- in
> the house set up.
You should have a ground bus bar in the sub panel that is insulated so
the ground is carried back to the house ground rod.
Lew
>
<[email protected]> wrote in message
news:[email protected]...
> Great! Thanks for the information. I really want to meet code
> requirements -- but the code is a little confusing to me (newby).
>
> I don't have the neutral and grounding bars bounded. And the
> grounding bar is connected to the grounding bar in the main panel and
> to two grounding rods outside the garage and separated by about 7 feet
> (what a workout).
>
Someone correct me if I'm wrong, but doesn't code state one ground form or
another, depending on attached or detached structures? Wouldn't a 4th wire
and separate ground rods be a code violation - more than one ground point?
--
-Mike-
[email protected]
On 6 Sep 2006 18:50:02 -0700, [email protected] wrote:
>I have a detached garage that I have added a feeder panel (sub-panel)
>to for extra power. Code required that it was a four wire connection
>from the main panel in the house (Two hot, ground, and neutral). Also,
>per code the two ground rods were required and the neutral bus was to
>NOT be connected to the grounding bar in the subpanel.
>
>Question: (finally) I would like to add a 220v outlet for a dust
>collection machine -- easy wiring, only three wires, two hots and a
>ground -- does the ground go to the grounding bar? This makes me
>nervous as there is not dedicated neutral connection and the neutral
>and grounding bars are not bonded -- as they would be in a normal -- in
>the house set up.
You are doing fine so far. The ground goes to the ground bus, which
will be at ground potential as compared to the floor. If you connected
to the subpanel neutral the case of your dust collector would be a
couple volts above ground due to the voltage drop(rise) from the load.
Your fault path is through the ground, back to the house and then to
the neutral.
On 6 Sep 2006 18:50:02 -0700, [email protected] wrote:
>I have a detached garage that I have added a feeder panel (sub-panel)
>to for extra power. Code required that it was a four wire connection
>from the main panel in the house (Two hot, ground, and neutral). Also,
>per code the two ground rods were required and the neutral bus was to
>NOT be connected to the grounding bar in the subpanel.
>
>Question: (finally) I would like to add a 220v outlet for a dust
>collection machine -- easy wiring, only three wires, two hots and a
>ground -- does the ground go to the grounding bar? This makes me
>nervous as there is not dedicated neutral connection and the neutral
>and grounding bars are not bonded -- as they would be in a normal -- in
>the house set up.
Absolutely attach the ground to the ground bar, which should be
attached to the main (panel) ground and to the ground rod at the
garage. Do not bond the sub-panel neutral to the ground. That's
code and correct, whether for a single or two pole circuit.
[email protected] spake thusly and wrote:
>Question: (finally) I would like to add a 220v outlet for a dust
>collection machine -- easy wiring, only three wires, two hots and a
>ground -- does the ground go to the grounding bar? This makes me
>nervous as there is not dedicated neutral connection and the neutral
>and grounding bars are not bonded -- as they would be in a normal -- in
>the house set up.
Sounds like you have it right (that is why it is a grounding
bar), but you might want to double check with local codes (I know
yadda yadda, but if anything WERE to ever happen.....)
What you have is 220V AC which is a bit different than 110 AC
which goes hot to neutral. 220V in this application goes
"hot to hot".
Steve
--
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On Sat, 9 Sep 2006 19:34:21 -0400, "Mike Marlow" <[email protected]>
wrote:
> Wouldn't a 4th wire
>and separate ground rods be a code violation - more than one ground point?
Nope, the additional rods simply become part of the grounding
electrode system. The more the better. What does only happen once is
the main bonding jumper where the neutral gets bonded. That is
supposed to be in the service disconnect enclosure.
There is one exception that allows a 3 wire feeder and a bonded
neutral in a separate building but that will be going away in 2008