Ground wire…

[FL Guy]

Just recently found out that if your sub panel box for a detached metal garage has a certain amount of “ohms” you need a second ground rod.
I saw where folks just install the second rod and don’t even try to get an ohm reading.

With that being said, can you tie into the existing ground wire coming out of the building and run it 10’+ away to another ground rod or do I need to come directly out of my sub panel box with a new ground wire?

Based on the picture, Can I do "A" or do I need to do "B" ?

 

[pattenp]

You can do (A), come off the first ground rod to add a second rod. The second (auxiliary) rod needs to be at least 6ft from the first rod. The continuous wire requirement is from the panel to the first rod. The wire to the second rod can be attached to the first rod by using the existing rod clamp or by adding a second clamp.

 

[FL Guy]

thanks!

 

[Norcal]

If the rod is does not have resistance to earth of 25 ohms or less a second one must be driven at least 6 feet apart from the first one, since the testing equipment is expensive & need to be qualified to use it, it is better just to drive the second rod, but if new construction the smarter solution is use a UFER, AKA a CEE, a Concrete Encased Electrode, and forget about driving ground rods.

 

[PCustoms]

Just recently found out that if your sub panel box for a detached metal garage has a certain amount of “ohms” you need a second ground rod.
I saw where folks just install the second rod and don’t even try to get an ohm reading.

With that being said, can you tie into the existing ground wire coming out of the building and run it 10’+ away to another ground rod or do I need to come directly out of my sub panel box with a new ground wire?

Based on the picture, Can I do "A" or do I need to do "B" ?

When was the original install done?

 

[FL Guy]

If the rod is does not have resistance to earth of 25 ohms or less a second one must be driven at least 6 feet apart from the first one, since the testing equipment is expensive & need to be qualified to use it, it is better just to drive the second rod, but if new construction the smarter solution is use a UFER, AKA a CEE, a Concrete Encased Electrode, and forget about driving ground rods.

I don’t have the equipment to test the ohm reading so I’d rather be safe than sorry and spend 30 bucks on a little bit of copper wire, and a new ground rod

 

[FL Guy]

When was the original install done?

6 months ago.

 

[wyliesdiesels]

Just recently found out that if your sub panel box for a detached metal garage has a certain amount of “ohms” you need a second ground rod.
I saw where folks just install the second rod and don’t even try to get an ohm reading.

With that being said, can you tie into the existing ground wire coming out of the building and run it 10’+ away to another ground rod or do I need to come directly out of my sub panel box with a new ground wire?

Based on the picture, Can I do "A" or do I need to do "B" ?

Its not the subpanel that would have a certain number of ohms. Its the ground rod. Code requires a second rod if the first rod doesnt have 25ohms or less resistance to earth.

I highly doubt you have the equipment or know how to test it, so just drive a second rod