Subpanel Grounding Question
 

Hello all,

Just mounted my 70 amp subpanel on my garage wall. My question
is: Do Subpanels need to be grounded with their own separate ground
rod. I remember someone saying that a 100 amp or above does but not
if less then that. Obviously the panel will be grounded through the
feeder cable.

Subpanel Grounding Question
 

wrote in message
oups.com...
Hello all,

Just mounted my 70 amp subpanel on my garage wall. My question
is: Do Subpanels need to be grounded with their own separate ground
rod. I remember someone saying that a 100 amp or above does but not
if less then that. Obviously the panel will be grounded through the
feeder cable.


Whoever told you that was wrong. Amperage of the panel does not change the
ground requirements.
Is your garage attached? If yes, then you do not need to add ground rods.
Run a 4-cable feeder to the sub
from the main and pull ground through that. Make sure that ground and
neutral are not bonded in the sub.
Remove the bonding strap from the neutral bar. If your garage is not
attached, then you need to add
ground rods.

Subpanel Grounding Question
 

Thanks J.A.

The garage is detached so I will install the ground rod tomorrow
with #6 copper. I already bought 10/3 UF and am going to start
trenching and running 1" conduit in the morning. I understand the
neutral bus bar issue but never was able to understand why the bonding
screw is to be removed. If neutral and ground are bonded at the main
panel why is it bad to bond them at the sub? Don't worry...I will
separate them but am just curious.

Rod

Subpanel Grounding Question
 

On May 24, 7:53 pm, wrote:
Thanks J.A.

The garage is detached so I will install the ground rod tomorrow
with #6 copper. I already bought 10/3 UF and am going to start
trenching and running 1" conduit in the morning. I understand the
neutral bus bar issue but never was able to understand why the bonding
screw is to be removed. If neutral and ground are bonded at the main
panel why is it bad to bond them at the sub? Don't worry...I will
separate them but am just curious.

Rod

If they are bonded together at the subpanel then the neutral current
will be split evenly between the neutral and the equipment grounding
conductor between the subpanel and the main panel. The equipment
grounding conductor is not suppossed to carry current under normal
conditions.

Subpanel Grounding Question
 

On 2007-05-25, wrote:

I already bought 10/3 UF and am going to start trenching and running
1" conduit in the morning.

Since you are using 10/3 UF are you going to be putting a 30 amp main
breaker in your 70 amp subpanel?

Cheers, Wayne

Subpanel Grounding Question
 

On May 25, 8:56 am, Wayne Whitney wrote:
On 2007-05-25, wrote:

I already bought 10/3 UF and am going to start trenching and running
1" conduit in the morning.

Since you are using 10/3 UF are you going to be putting a 30 amp main
breaker in your 70 amp subpanel?

Cheers, Wayne

Good catch. I was focused on the grounding question. 10/3 would make
a pretty useless subpanel.

Subpanel Grounding Question
 

"Eric9822" wrote in message

Good catch. I was focused on the grounding question. 10/3 would make
a pretty useless subpanel.


Why? It runs all my power tools with no problem at all, including a
tablesaw and dust collector together. Sure, bigger is better, but when I
ran mine there were other considerations that made 10/3 an easy choice at
the time.

Subpanel Grounding Question
 

"Edwin Pawlowski" wrote in message
t...

"Eric9822" wrote in message

Good catch. I was focused on the grounding question. 10/3 would make
a pretty useless subpanel.


Why? It runs all my power tools with no problem at all, including a
tablesaw and dust collector together. Sure, bigger is better, but when I
ran mine there were other considerations that made 10/3 an easy choice at
the time.


I agree with Edwin.

All I ran to my detached garage was 10/3 wg, used a 60 amp, 4 circuit
subpanel and a 30 amp breaker in the main box.

That would handle anything I wanted to use since I don't weld.

How many tools can one guy use at one time???

Subpanel Grounding Question
 

"Colbyt" wrote in message
m...

"Edwin Pawlowski" wrote in message
t...

"Eric9822" wrote in message

Good catch. I was focused on the grounding question. 10/3 would make
a pretty useless subpanel.


Why? It runs all my power tools with no problem at all, including a
tablesaw and dust collector together. Sure, bigger is better, but when I
ran mine there were other considerations that made 10/3 an easy choice at
the time.


I agree with Edwin.

All I ran to my detached garage was 10/3 wg, used a 60 amp, 4 circuit
subpanel and a 30 amp breaker in the main box.

That would handle anything I wanted to use since I don't weld.

How many tools can one guy use at one time???

I dunno. When I ran a subpanel in my attached garage, I ran it as a full
100A sub, with #4 AWG,
the works. I figured I'd just overdo it from the start so I would not have
to redo it later. However, I agree with you.
10/3 wire in a garage sub would be more than enough garage power for most
folks.

Subpanel Grounding Question
 

wrote in message
...
On Fri, 25 May 2007 22:54:12 -0500, "J.A. Michel"
wrote:

I dunno. When I ran a subpanel in my attached garage, I ran it as a full
100A sub, with #4 AWG,

It couldn't have been "full 100a" with 4 ga wire, you really need 2.

The inspector didn't have a problem with it.

Subpanel Grounding Question
 

wrote in message
...
On Sat, 26 May 2007 00:18:17 -0500, "J.A. Michel"
wrote:

I dunno. When I ran a subpanel in my attached garage, I ran it as a
full
100A sub, with #4 AWG,

It couldn't have been "full 100a" with 4 ga wire, you really need 2.

The inspector didn't have a problem with it.


He missed a violation, it happens. Perhaps he just decided you will
never use the 85a the #4 is good for but it still is not really legal.
A lot of people mis-apply 310.15(B)(6). It is onlky for the main
feeder or service conductors to the whole dwelling. That assumes the
load diversity you have in a home.,

#4cu THHN 90C is 95A not 85