wiring a sub panel in garage

[Glotharg]

I didn't want to start any arguments over this.. Just looking for help. If I put the earth ground back into the circuit, will it change anything electrically or just make it 'up to code'?

[BBurger]

The idea here is to get you factual information, based on your broken descriptions of the problem. The ground bar debate is not a side issue, and you could help to clarify the issue by stating whether or not your garage is separate or attached to the house. As for changing things electrically vs 'up to code', there is no point making symptoms go away or change if you don't fix the underlying problem(s).

You stated your initial problem as:
Somehow, I am getting a completed circuit once I connect the sub panel to that ground wire going outside.

and:
What goes wack-job, is when I hook up the 2nd white braded wire comming from the 7' burried grounding rod, to the bottom of the bound lug bank.

From reading your posts and wrestling with your terminology (it's "bonded" - bound is the past tense of bind, not bond), I take this to mean that you had a spark (and probably voltage) between the outside ground rod and the ground bar in the subpanel, and that ground bar is connected via a wire to the service neutral bar. Is this correct?

If so, you either have ground current crossing your property and short-cutting on the ground wire running between the garage and house rods... OR you have a grounding problem at the house panel which is showing up at the garage installation. Is your garage located between the utility transformer on the pole and your house?

In either case you should have a pro come in and troubleshoot this in person. He can tell at that time whether your local utility is part of or all of the problem.

[HayZee518]

sub panel

look at the following diagram. as you can see, the secondary of the step down transformer the midpoint of the two windings is grounded by means of a driven ground rod supplied by the utility. at the house, a water pipe in intimate contact with the earth forms the ground return path. where this isn't practical, two grounds rods driven 6 feet apart and connected to a continuous length of #4 wire terminating at the service entrance panel constitutes the ground return path. in sandy soil, ground resistance is very high and the return path may be broken or intermittent. sandy soil is treated with salt, sodium chloride to decrease the ground resistance to zero or as close to zero as possible.

[HayZee518]

BBurger - I still maintain that a driven ground is not necessary because of the provision in the NEC I pointed out whereas the four wire, the ground is run with the sub panel conductors in the same pipe or cable to the detached garage.
your quote: Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.
there is a grounding electrode installed at the house service entrance therefore you don't need the ground rod at the garage!

[BBurger]

I looked at your graphic, and it illustrates the need for a grounding electrode at the service --- but that doesn't negate the requirement of 250.32(A) that buildings supplied by feeders ALSO require a grounding electrode - even if the equipment grounding conductor is run with the feeders.

Here's a graphic that actually applies, as it's from the 2005 NEC Handbook. It illustrates a 4-wire feed to a separate building and the required connection to a ground bar at both the service building and the remote building.

You give some pretty good advice at times, and you've certainly taken a lot of time to try to figure out what this poster is describing. But you have a blind side about this issue. 250.32(A) clearly requires a grounding electrode at all buildings supplied by feeders. There is no exception for 4-wire feeds. Anyone can Google "subpanel ground rod" and find this information. It's bad advice to tell anyone to disconnect the groundbar at a remote building, and it only serves to undercut the credibility of your good advice.

[HayZee518]

in your diagram, is it a requirement to have an auxillary ground bar installed in the service panel? because that is what the picture shows. [left hand picture] it shows the aux bar, and the neutral bar all connected together and I guess this is fulfilling the requirement of bonding the neutral to the cabinet. plus the inclusion of a secondary grounding electrode and/or primary grounding electrode[ water pipe or driven electrodes.]

[BBurger]

It's not a requirement to have a separate ground bar at the service panel, but I think they are just illustrating the presence of a main bonding jumper this way. Code is worded to apply beyond residential, and many commercial/industrial services have large grounding bus bars bonded by bars to even larger neutral bus bars. No green screws there

[HayZee518]

I'm well aware of the grounding requirement. I've worked 19 plus years at a hydro generating facility in Massachusetts where all grounds larger than 350mcm is one-quarter by 4 inch bus bar. This is especially true of the 4160 motor control centers that makes exclusive use of bus bar for station grounding purposes. The place I worked believed in over-kill of grounding and bonding of its service equipment. If the code required 250 mcm for grounding then the utility doubled the requirement and put in 2X the cable diameter. Equipment grounds for the step up transformers [13,800 to 345Kv] all used multiple lug flexible grounded connections to the embedded ground bus that ran all over the station. Out in the 345 switchyard, the ground grid ran all over the base of the three phase loop and out from the switchyard fenced in boundary about twenty feet beyond the fenced in perimeter. Every corner, every four feet in any direction was a driven ground. Cad welded ground cable was at every grounding point.

[buckofdurham]

One point I don't know if Burger said is. In 05 code three wires was acceptable to the sub panel. In 08 of course you need 4.
In 05 you would bond the neutral to the can. And to the ground rod.
You have always needed a ground rod at a detatched garage.
.

[Glotharg]

I will hold the spike steady.. and when I nod my head, hit it!

please close this thread.. it has gone beyond its needs.
Thanks to HayZee518 for all his help, Thanks to others who chimed in.

[HayZee518]

In 1992 I was doing sub panels and the Mass inspector said 4 wires. underground in conduit four wires. overhead as in detached service drop four wire SER.

[mrcaptainbob]

information...

Am closely following this thread. Very good dialogue. Great info. Great give and take. Thanks, guys.....very informative.

[Speedy Petey]

Glotharg, no need to close this thread. This is a good professional discussion and others may have questions.

Hazee, BBurger is completely correct in that ANY structure served by a feeder does require some form of grounding electrode. 250.32(A) is very clear on this. This section has been in place for quite some time.

buckofdurham, is also correct in that under earlier codes, and very specific circumstances, a 3-wire feeder is/was definitely allowed, and the sub-panel is/was treated like a main panel. This was found in 250.32(B) prior to the 2008 edition.