Ground Rod Wiring Question

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Old 04-07-10, 06:57 PM
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Question Ground Rod Wiring Question

Hi Guys.
I have a question concerning the wiring from a sub panel to the ground rod. Looking at the old panel and the Main Panel in the house, it looks I should use a solid copper #8(?) AWG wire, correct? Can it have insulation or not?
Also, in both panels, it appears the wire was just stuck through a small hole through the bottom - the new panel I'm installing in the garage does not have a small hole - just the knockouts. Is it ok to drill a small hole in the bottom of the box?
Does this ground wire have to be run separate?
Could I drill a small hole in the PVC Conduit LB where the conduit enters the garage wall and run the ground wire in with the cables?
Again - thank you guys for you advise and help.
 
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Old 04-07-10, 07:02 PM
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The size of the ground wire depends on the size of the feeder which you have not furnished. Wire to a ground rod should be bare solid or bare 7 strand copper. Typically, #6 is the largest size ground wire you'll ever have to run to a ground rod.
 
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Old 04-07-10, 07:15 PM
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Oh - sorry.
It is a 90 amp circuit. I'm running 2-2-4-6 from the Main Panel.
 
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Old 04-07-10, 07:18 PM
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If the #6 is a ground from the main panel, you don't need an additional ground rod.
 
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Old 04-07-10, 08:06 PM
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It wasn't clear , is this attached or detached garage?
 
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Old 04-07-10, 08:22 PM
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Originally Posted by CasualJoe View Post
If the #6 is a ground from the main panel, you don't need an additional ground rod.
A rod would be needed in a deteched structure.

I am not sure if this applies as there is a question as to attached or detached.
 
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Old 04-07-10, 09:51 PM
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Looking at the old panel and the Main Panel in the house,
Sounds like one structure to me.
 
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Old 04-08-10, 04:36 AM
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Separate structure - It is a detached garage.
 
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Old 04-08-10, 06:04 AM
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Then yes, you must have a ground rod. You may run it without conduit, but if you do it must be 6AWG. If you protect it with conduit, you can go down to size 8AWG. If your detached garage has any metal waterpipes, they should also have the same size conductor brought to and bonded to them.

Be sure you seperate the neutral and ground in the sub panel. They cannot be bonded together like they are at the service point.

I would not drill through the LB to run the above mentioned conductors. I would drill a small hole in the panel, if one is not provided. The LB opening must be filled with duct seal to prevent condensation due to temperature variations from the underground pipe to the panel. Drilling a hole in the side would recreate that issue.
 
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Old 04-08-10, 07:08 AM
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Most panels have a little itty bitty knockout in the bottom corner to run wire thru.
 
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Old 04-08-10, 07:04 PM
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If you protect it with conduit, you can go down to size 8AWG.
IF you protect the ground wire with metallic conduit, the conduit must be properly grounded with either a grounding locknut or bonding bushing. I would prefer PVC conduit for a ground wire if it is in conduit, but the most common method I have seen for securing a ground wire is to use copper plated 1-hole straps, such as the Jiffy 105C.
 
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Old 04-09-10, 03:16 AM
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Thank you all for your replies.
The old box had a #6 solid copper bare wire so I just got 7 ft of new wire and cleaned off the old clamp and what was sticking out of the ground of the old rod. I could not find an itty bitty knockout so I drilled a small hole in the bottom of the panel and ran the wire outside the pvc conduit for the feeders. Pretty much as it was on the old box using the same hole/slot made into the bottom plate of the wall framing.
I wired the panel per Bluto's line drawings in the Topic Section titled Wiring a Garage Subpanel- 4 Wire Feeder, leaving the neutral unbonded from the ground.
On another note - this morning I read the Topic Section pertaining to the the number of receptacles past a GFI and the opinions of 3 receptacles per GFI - and I'll have 4 receptacles on each wall so that will work for me, too.
You guys are just great!
 
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Old 04-09-10, 03:21 AM
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Oh yeah, RHefren mentioned about condensation and not drilling through the LB - which I did not, but he indicates concerns with underground piping (which I have) and condensation creeping into the panels.
Is the PVC conduit where it enters the Sub and Main panels to be filled with sealer (RTV) around the feeders to keep condensation out of the box(es)?
 
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Old 04-09-10, 07:34 AM
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Originally Posted by 66Cyclone View Post
Oh yeah, RHefren mentioned about condensation and not drilling through the LB - which I did not, but he indicates concerns with underground piping (which I have) and condensation creeping into the panels.
Is the PVC conduit where it enters the Sub and Main panels to be filled with sealer (RTV) around the feeders to keep condensation out of the box(es)?
All conduits that go between indoor and outdoor locations must be plugged with duct seal. This prevents temperature and humidity variations from causing condensation on electrical parts, which can cause some serious arcing and deterioration. It is a commonly missed step, but required by code and a very good idea if you'd like your panel to last more than a few years.
 
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Old 04-09-10, 04:25 PM
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RHefferan;
Thank you! What is "Duct Seal" ? Is it like RTV or Caulking of some kind? Can I find it at a Home Improvement Store, like Lowe's, or is it something I should go to an Electrical Supply for?
I'm glad I asked....it makes total sense - but may have been missed had you not brought it up. Thanks again.
 
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Old 04-09-10, 07:54 PM
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Originally Posted by 66Cyclone View Post
RHefferan;
Thank you! What is "Duct Seal" ? Is it like RTV or Caulking of some kind? Can I find it at a Home Improvement Store, like Lowe's, or is it something I should go to an Electrical Supply for?
I'm glad I asked....it makes total sense - but may have been missed had you not brought it up. Thanks again.

Many big box store should have the duct seal in stock and it will be found in electrical department.

They should be only few Euros / Dollars and it will look like sorta like a brick but smaller in size for your useage almost like play doh putty.

Merci,Marc
 
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Old 04-09-10, 08:47 PM
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Duct seal is sometimes called dum-dum. I think a 1 lb package is the smallest amount sold and should do the job for you.
 
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Old 04-09-10, 09:13 PM
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OK - Yeah dum-dum, I know what that is - used to use it years ago in the car dealership to seal leaks between welded body panels.
Thanks! I'll get some and shove it down the underground conduit feeder openings in both boxes.
Finished wiring and turned the power on to the sub panel this morning and everything worked - Thanks to you guys!!
Let's see, the duct sealer and change out a few receptacles to GFI and I think that is about it, the inspector is scheduled to come Monday.
Better ask while I'm here - is it ok to have 15 amp receptacles on a 20 amp breaker circuit? The 20 amps came with the new panel.
 
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Old 04-09-10, 09:16 PM
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yeah as long they are duplex receptales it useally not a issue in USA side but in Canada side then it is a no-no they can't do that.

However if singleplex then with 20 amp circuit you must use 20 amp singleplex can NOT use 15 amp singleplex at all.

Merci,Marc
 
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Old 04-11-10, 05:52 PM
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Thumbs up

Yep - they are duplex. Thanks for the information.
 
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