To ground, or not to ground...

[K30]

I think it mostly came into existence from fires, so kinda!

 

[Pevehouse]

So I am currently upgrading my electrical service in my garage/shop.
Previously what I had in the garage was 120V only. There was a simple dis-connect switch to control the lights and outlets. There is a 10/3 cable dug underground running from the main breaker panel to the garage. This cable has NO ground wire in it (wasn't important in the 50's..) Yes, I am just plain lucky that I have never had anything short out in the years I've lived here!
I am installing a basic sub-panel in the garage now so I can have 220V power on breakers. My dilemma is that I have no ground connection with the main breaker panel. Am I correct in thinking that I must run a ground wire back to the house, and connect to the ground bus in the main panel? I plan to place two earth ground rods in the process.
I think I know the answer but am hoping for a qualified opinion on this.
Thanks!

Well I’m not qualified,lol however I just had to do what you are doing a few years back. Had to sink and bond 2 grounding rods. The original that came with the house was only a foot long. The house was built in 2000 so it must have just been a lazy electrician

 

[WesPete66]

2 grounding rods. The original that came with the house was only a foot long. The house was built in 2000 so it must have just been a lazy electrician

One foot deep, or twelve feet, all looks the same at the surface..

 

[dkemppai]

Had to sink and bond 2 grounding rods. The original that came with the house was only a foot long. The house was built in 2000 so it must have just been a lazy electrician

I've heard of electricians driving ground rods with a hacksaw. That must have been what happened there.

Built the garage 15 years ago, house 7 years ago. Main service is on the garage, two ground rods, rebar bonded to the ground rods and panel is where ground and neutral are bonded. House is a sub panel, that required two ground rods also. Those are also bonded to the rebar in the footings, and bonded to the separated ground in the panel, which is all also bonded to the main panel in the garage.

There's been chatter about different inspectors and code in different areas. AFIK, Ground is ground is ground, no matter where you are. That is only ever bonded to neutral at 1 point, which is the main service entrance. If anyone knows of any modern US installation where that is different by code, let me know. But honestly, I'd be surprised.

 

[Weldingrod1]

Some grounds are harder to get working I had to use a pair of 300' rods to get down to the water table (high desert). The pair let me test down one and up the other with an inductive tester to be sure I had actually suceed!

Sent from my SM-S911U using Tapatalk

 

[Provincial]

Some grounds are harder to get working I had to use a pair of 300' rods to get down to the water table (high desert). The pair let me test down one and up the other with an inductive tester to be sure I had actually suceed!

Sent from my SM-S911U using Tapatalk

Until the water table drops from excessive pumping!

 

[Provincial]

I've heard of electricians driving ground rods with a hacksaw. That must have been what happened there.

Built the garage 15 years ago, house 7 years ago. Main service is on the garage, two ground rods, rebar bonded to the ground rods and panel is where ground and neutral are bonded. House is a sub panel, that required two ground rods also. Those are also bonded to the rebar in the footings, and bonded to the separated ground in the panel, which is all also bonded to the main panel in the garage.

There's been chatter about different inspectors and code in different areas. AFIK, Ground is ground is ground, no matter where you are. That is only ever bonded to neutral at 1 point, which is the main service entrance. If anyone knows of any modern US installation where that is different by code, let me know. But honestly, I'd be surprised.

I vaguely remember that a "derived" system, like a transformer, may be treated like a separate system for grounding, which makes a kind of sense because the output windings are insuulated from the input windings

 

[rwdenney]

My shop has a Ufer ground—the rebar in the foundation-wall footing is electrically connected around the whole perimeter of the shop and that makes a better ground than any rod. There is no electrical connection with the house. The computer network connection is wireless using a couple of Ubiquiti Nanostations.

Putting the shop on its own meter adds cost but means I have 400 amps in the shop. I did have to show the power company the cut sheep for the on-demand boiler for the radiant floor. (94 amps!)

Rick “but not three-phase” Denney