Ground rod for detached sub panel


Hi Everyone!

I'm new here and my question is:

When installing 2-5/8"x8' ground rods for a detached garage Sub-Panel ... The rods will be driven in to the ground 6" below grade and spaced 8' on center. Assuming that the roof has a 12' overhang with a gutter system draining to the rear of the garage and the rods will be install on the same side as the gutter system ... where in relation to the side of the garage/roof overhang should the rods be installed?

One co-worker says it should set beyond the roof overhand where the grade is slightly higher and less water pools(dry soil provides better grounding). The other persons states it should approx 6"-8" from the garage and under the overhang where the water pools slightly(wet soil provides better grounding).

Also, would it be ok to attached the single ground conductor (#8AWG) from the ground rods to the outside of the Schedule 80 PVC using plastic ties(this conduit runs back to the Main Panel at the house and...

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Hey guys - This is neat, especially the diagrams Stubbie found. A further question about a ground rod in the detached building. In my case the feed is 4-wire (70 ft) from the garage to the house. I'm off grid and originally had the inverter system in the house with a feed to the garage, but then I moved all the panels/batteries/inverters to the garage, in effect switching what was the main vs subpanel.

Question concerns the ground rod at the house (now subpanel). I always assumed it was better to have ground rods at both ends as long as they were tied together. But, years ago, several electricians (and one inspector) told me, no, do not use a second ground rod in the detached structure, so I haven't been doing it. But now I see you guys saying that it's not only a good idea but code requirement. Right? That's 2005 code? Wow, I missed it completely. Thank you. So, I will reconnect the house (subpanel) ground rod this afternoon (keeping neutral and ground completely...

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So I'm almost done installing my subpanel, and I'm 99% certain how to do the final connections, but I just want a sanity check.

Ground and Neutral have separate bars in the subpanel, neutral is not bonded. In the main panel, neutral IS bonded and all the ground and neutral wires go to the same bar. When connecting my subpanel feeder wires BOTH neutral and ground wires connect to the neutral bus bar, correct? Thanks.

Is this subpanel in a detached structure? If so, you will need ground rods at the subpanel location.

Is installing a ground rod for a detached structure sub-panel a NEC requirement? I've been out of the electrical game for several years, the last code book I have is 1996 and I can't find it.

Is installing a ground rod for a detached structure sub-panel a NEC requirement? I've been out of the electrical game for several years, the last code book I have is 1996 and I can't find it.

They allow both approaches for a detached structure. but...

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Please Note: Mike Bee is a non-member guest and is in no way affiliated with InterNACHI or its members.

I have some questions about proper grounding and specs for a subpanel in a shed. Here’s an overview:

Distance from the main panel (at the house) to the shed is about 110’. Using 10/3 wire. At the main service panel = a double-pole 20-amp breaker (two 20-amp breakers with the switches connected). Only using 20 b/c of the long run from panel to sub.

At the shed: Subpanel for 4 circuits, but plan is only for two 20-amp circuits (or a 15 and a 20). Two 8’ ground rods, 6' apart, connected with #6 copper wire.

These are my questions:

1. Grounding at the shed Part 1 - what is the proper connection for the #6 ground wire at the shed? To the neutral buss bar?

2. Grounding at the shed Part 2 - What happens to the ground that’s coming from the main panel (the bare wire in the 10/3 “feed”)? Just leave it disconnected at both ends (at the sub...

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Hi all -
I am in Denver Colorado, and I am building a detached garage.
To power the garage, I have installed a sub panel, fed from my home's service panel. I asked the inspector what he wanted to see in this installation, and he told me what he wanted - with one major exception: he mentioned nothing about a Ufer ground.

I poured my pad in Dec - monolithic slab. The garage was framed, and I ran 3 6 gauge THHN (-2) wires through underground conduit to the garage, OCPD is a 50 amp breaker on the service panel, which is on the house. I drove a grounding rod at the garage, which is bonded at the sub panel with #4 solid copper. I called in my rough, and I flunked because he says I need a Ufer ground (he called it Uffer, but I figure that is what he is referring to).

10 weeks ago, I asked this guy specifically what he wanted to see to establish that sub panel, and he never mentioned this requirement. The guy who did my flatwork has been building garages in Denver for 20...

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Originally Posted by


I'm glad I read up on the subject. It sure would have been easier to do what Rod suggested but it also would have been very unsafe. Now I just need to decide how bad I really want to snake a fourth wire down 75 feet of 1" conduit. Besides adding a grounding rod at the subpanel, I'm tempted to leave it as is, at least for now. Which brings me full circle and back to the whole point of the thread, as stated in my questions quoted below:

So does anyone have any thoughts on this?

Sorry - but what I suggested is not unsafe...... removal of the bond between ground and neutral at the sub panel is required in your case should you add a ground at the sub panel.

This from Mike Holt (not a general discussion of concepts - but (rather) his response to a question as to the requirements of the code as relates to this subject. Mike Holt is (in my opinion anyway) the best of the best when it comes to electrical code...

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Originally Posted by

Matt Marsh

Jason, A separate building always requires a grounding electrode system in addition to the equipment grounding conductor that you mention. The only exception is if the separate building is fed with just a single branch circuit (2014 NEC 250.32a). If you are using rod type electrodes, you really need to drive two of them, at a minimum of 6' apart. The only way that you can get by with a single one, is if you can prove by measurement that the ground resistance is 25 ohms or less. The measurement must be performed with a dedicated ground resistance meter, something that very few contractors have. It is almost always easier and more cost effective to satisfy the NEC requirement by supplementing one ground rod with an additional one (250.53(a)(2). Although the minimum size grounding electrode conductor is typically #8 copper for a 100 amp service (it's actually determined by feeder size, not amperage), the NEC requires that conductors smaller than...

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No clue. I think there's a right way and a wrong way. Your current way sounds like the wrong way (and is the same way my barn is currently wired.) A guy from an electrical supply store had a complete list for me of everything I'd need to bring it to code. It included an underground feed, a "sub panel" in there, and a separate grounding rod for the barn. Nearest I could find for you is that something changed in the NEC in 2008 concerning separate grounding; at least I saw it mentioned on two different sites. And, the two different discussions seemed to come to opposite conclusions, so I don't know which is correct & which is wrong.

A separate grounding rod would be "safe" for the garage - but I really don't think it would bring your garage up to code.

Click to...

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Expert: Bob Sponaugle - 12/28/2007



I have recently installed a 100 amp breaker in my 200 AMP Home service Cutler Hammer Box to support my detached garage. I ran #2 Four wires 22' in conduit to my 100 amp Cutler Hammer Sub Panel.

I have four Questions.

When connecting to the 200 AMP Service in my home I connect the two hots to the breaker.
I have a sub hole right beside where the neutral wire from the meter can connects into the 200 AMP box could I connect the neutral from my Sub panel there or do I need to be below the main 200 AMP Breaker.

My third question is about the Ground in the 200 amp box in my home (it has a ground wire connecting to a ground bar outside. Can I connect the ground wire from the Sub Panel to the ground bar in this box? I will have a gas line running from the house to the Detached Garage.

The Third question is about the Sub Panel Box it didn't come with a Ground Bar in the box, I...

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No sure what you're referring to when you say no ground to main panel. Is this in the feeder to the garage or do you mean the circuits in the garage have no grounding wire back to the garage panel?

You also said Federal Pioneer panel. Those are usually sold in Canada. Are you in Canada? If so, you may want to repost in the Canadian forum -- they have some different rules from the NEC.

For pre-2008, there is no problem with the 3-wire feed as long as all 3 wires are insulated. The neutral does double duty as both neutral and ground, just like the wires from the power company to your house (that is also a 3 wire system).

Because you have a panel, you need a ground rod (actually two). Connect the ground electrode conductor (use #6 copper) from the garage panel neutral bar to the first ground rod. Then, either keep it going unspliced, or run a new segment to the second rod which must be at least 6' from the first (10' would be better).

Put the green bonding screw...

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The following are copies of Code sections that apply to your questions.

225-31. Disconnecting Means Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.

225-32. Location The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in Section 230-6 shall be permitted to be utilized.

Exception No. 1: For installations under single management, where documented safe switching procedures are established and maintained for disconnection, the disconnecting means shall be permitted to be located elsewhere on the premises.

225-33. Maximum Number of Disconnects

(a) General. The disconnecting means for each...

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Changes to the Electrical Code now REQUIRE all unattached buildings with sub panels, to have the Neutral Bar Grounded with #6 wire to the panel box then to a grounding rod in the earth. (Rule 10-208)

You CANNOT use the ground included in say #10/3 wire as your sub panel ground anymore.

You are to treat the sub panel just as a service that is coming in from the meter, the only conductors that should be entering your sub panel now are your 2 Hot Feeds, and your Neutral. (no ground from the main panel.)

Now the confusing part, Rule 10-208 (b) states that you can ground any metal non current carrying components (outlet boxes) through a separate conductor back to the main panel if the building does not house livestock. However, since you must now have a bonded neutral in sub panels, this is more of a pain to attempt since you have a separate grounding circut right there...

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FAQ for Wiring Detached Building

New breaker box in a detached garage. 1

230v table saw for use in your detached garage. 3

Run electric to Pole Barn. 4

Rewiring Garage, what size wire to run?. 4

Wiring Garage 60ft from House. 5

Plastic or Metal Conduit?. 5

Wiring a detached garage. 6

Load center for attached garage. 8

Wiring in a pole barn. 9

Electrical service for shed/workshop. 10

Source (

· QUESTION - How do you run a new breaker box in a detached garage from the existing breaker box in the house?

· Answer - If your current breaker box is 200 amps then it is fairly simple. Install a 30 amp breaker (house box (a)) to run the garage (b) box outlets. Depending on the distance from box a - b use a suitable gauge wire for...

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Author Information Topic: Why don't you bond the neutral at a sub panel? Member

Name: Joel Crawford
Location: Louisiana
Title: Student
In Trade Since: 1994
Registered: Jul 2002
Total Posts: 26

posted August 12, 2002 at 10:53 PM so why is it not allowed?? just curious. thanks.

also what's the equation for voltage drop?



Name: Ed MacLaren
Location: Canada
Title: Instructor
In Trade Since: 1955
Registered: Nov 2001
Total Posts: 701

posted August 12, 2002 at 11:20 PM If the neutral were bonded to the enclosures at both ends of a feeder (both panels), and the panels were joined be a another conductive path, such as an equipment grounding conductor (EGC), the EGC would be in parallel with the neutral conductor.

Can you see what hazard is caused by this connection error?

For your...

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Hello guys. Please excuse my ignorance, but I would really appreciate some help with some electrical questions. I am wanting to run power from the 200 amp main feeder breaker that is feeding my house.

I have this breaker box as the feeder to my home:|1

My plan is to install a 100 amp breaker in this box to feed a subpanel in my shop about 100 feet away. The plan in my shop is to have about a dozen 120V receptacles and 1 or 2 220V receptacles for a mig welder.

Here is where I ask the stupid question. At this link below,, it shows several different examples of 120v or 240v service feeding the detached building.

My question is do I need to be running 120V or 240V to my shop? Please excuse my electrical ignorance, I'm here to learn. I'm guessing 240V right?

I've read several posts of other guys on this forum doing the same thing that has...

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About pigtails on neutral wires of a multiwire branch circuit.

Here is the code verbage.
300.13 B) Device Removal. In multiwire branch circuits, the
continuity of a grounded conductor shall not depend on
device connections such as lampholders, receptacles, and
so forth, where the removal of such devices would interrupt
the continuity.

And here is why. A 3 wire multiwire circuit is 240V + a shared neutral, split into 2) 120V 2 wire circuits. All is well when it is working and connected properly. However if the shared neutral becomes loose or disconnected the 120V circuits will become 240V circuits and anything connected to them will puff some magic smoke at a minimum, maybe belch some fire.

Actually that's an over simplification. What really happens is the 240V divides itself amongst the connected loads at the time. Some loads have low resistance and others higher, the voltage divides itself between whatever resistances are connected...

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Commonly accepted methods concerning wiring a utility controlled meter-base wiring a new main service rated panel installing the grounding system. Special concerns controlled by the utility companies.

Please pay special attention to the particular requirements involving your serving Utility Company. Each Utility Company often have specialized rules and requirements that differ from other Utility Companies that are also providing power to dwellings. Several Utility Companies may also serve dwellings in your locality. Research your electric bill, discover who your serving Utility Company is, then contact your serving Utility Company to gather any specialized rules that will apply to you, and your dwelling.

If you are building a new home where no home previously exists, then ask a neighboring property owner who serves his property providing his power or look at the nearest Utility power pole to the location where you plan to build you new home in order to...

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I purposely want a 2nd breaker separately fed apart from the home in front. The bill needs to be separate.

It is a workshop of sorts, but I want to follow code as best as I possibly can if not 100%.

I looked at Home Depot for wiring simplified and didn't see it, but I did see "Wiring 1-2-3" which I assumed to be pretty equivalent. It has been helpful so far and I jotted down some notes to ask the forum here so here we go:

Number 1:
Load Description x Quantity x Watts x Hours =Total (Watt-hrs/day)

Computer always on......2...............110.............24..............5280
Computer sometimes on...2...............50..............3...............300
Computer on a lot.......1...............130.............10..............1300
Fluorescent bulbs.......2...............15..............10..............300

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Welders, stoves and ovens are not considered continuous loads. Continous loads are loads that run for 3 hours or more, the welder will idle more than it will be welding, plus the duty cycle will be a limiting factor. Stoves and ovens cycle with thermostats, not a continous load.

If you are talking copper, #4 is allowed for a 100 amp panel that serves a residential dwelling. A shop might not fall under that allowance, and would probably need to be fed with #2.

If the garage is detached, a three wire feeder was allowed up till the 08 code, providing there are no other metallic paths between the buildings, not even a phone line. If your area has adopted the 08 code then you must run four wires. In either case a supplemental grounding rod is required at a separate structure. With a three wire feed, the grounding wires get bonded to the neutral, and to the cabinet, and to the ground rod(s). With a four wire feed, the grounding wires, the cabinet and the ground rod(s) all get...

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6 months ago, I completed the following job. It was approved, and inspected. After the power provider locked out the underground supply to the house, I removed a meter box from the side of a house, installed a dual lug meter box in it's place, and took off a 100Amp service to a garage. The existing house panel is 100Amp. The meter itself was rated at 200Amps. The same meter went back on. This was all inspected and good to go. so to reply to your above comment, there certainly is available, dual lug meter boxes for 200Amp meters- at least in this case. I know what you mean about putting a 100Amp breaker and sending that to the garage. In that case, the garage panel would be a subpanel, and I wonder since you don't ground the neutral in a subpanel, I wonder if you avoid the ground rod altogether? I've never put in a 100Amp branch circuit breaker before.

I was talking to an inspector about taking off a 100Amp garage service from the meter box that feeds a 200Amp...

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