PROPER sub-panel configuration.

[Dennis McCullen]

I bought a GE multi-use panel model number TM1210CCUG from the BORG and I was, at first, surprised at the layout. The panel is a 100 Amp breaker panel that is designed for use as either a main or a sub-panel. It contains a factory-installed 100 Amp main breaker that will serve as a cutoff in my workshop which is detached from the main house and is about 45 ft away. I will feed this panel by tying two hots to the 100A main breaker to "feed" the bus bars. I'll use a double 90 Amp breaker at the house to protect the #3 THHN feed wire in conduit. Two hots, 1 neutral, and a #4 ground. Maximum amp draw at the shop is expected to be 60 Amps occasionally, but 30 Amps normally. I'll have a 30 Amp feed to my camping trailer next to the shop and plug that up just before trips or once a month for maintenance.
I'm located in rural Tangipahoa Parish, LA and will not have inspectors to please; just the peace of mind ruling that I go safest possible route.

I'll post a picture and declare what I think I know about this, what I think needs to happen for my particular use of this breaker panel, and then hope for affirmation and or correction from the SC gang. I personally like to feel secure in what I do when installing new electrical. Thanks in advance.

The box came with an installed ground bar and what I believe are two separate neutral bars. This confused me a little at first then I remembered that some manus brag about twin neutral bars for ""speed and convenience".

- First - what I think I know. The left side neutral bar has two lugs?? I believe that is so that the incoming neutral can land on one lug and a "jumper" can go from the second lug and tie in the neutral bar along the right side of the breakers. I do not see a "tie bar" as some boxes have so I must ASSUME (that word gives me pause) that It is OK and necessary to use a #3 wire to connect the two neutral bars.

Next - the right side neutral bar has a green screw that must be removed.

The small grounding bar on the far right is where all the bare or green equipment ground wires land and a bare wire shall connect this bar to a ground rod placed in close proximity to this sub panel.

Thanks again from all you sparky-knowledgeable woodworkers. What a great place to hang out and exchange ideas!

[Reinis Kanders]

Tie bar is not there because it is sold as a subpanel.
You seem to be on a right track. I am an EE, not an electrician though.
Might be better with two ground rods. Tie service ground to the subpanel and to the ground rods.


Good info here:
http://ths.gardenweb.com/faq/lists/w...726007600.html


Here is a key quote from this site:
http://www.electrical-online.com/subpanel-installation/


"Neutral Bonding Jumper
This would be a good time to talk about the neutral bonding jumper.
In most panels you will find that the neutral buss bar (the common bar that is mostly isolated from the panel case), has either a long brass machine screw, or a metal strap of some kind that connects the neutral bar to the panel case, or ground.
In a subpanel, the neutral must be totally isolated from ground, so you must remove this screw or strap. The neutral and the ground can only be bonded in one location in a residential service, and that is in the main panel."

[Ed Weiser]

Hi Dennis,
As far as I can tell you've got it all pretty much right. The two bars on the insulating plastic backer are neutrals that are designed to be connected to each other (and the neutral feed) through the double lug. The separate ground bar is to the far right in your photo. Inasmuch as this is a subpanel it is correct to carry four wires back to your main panel--two hots, the neutral and a ground. Because the buildings are separate structures additional ground rods are also proper.

Oh, yes, since your RV is probably 30 amps 115 v (versus 230 v) the total ampacity of the load in your subpanel is a little less than you've described and you have "room" for additional 115 v circuits. And as already described, no bonding strap--neutral and grounding bars are kept separate.

Hope this helps.

[Dennis McCullen]

Thanks to you both for the replies.

Reinis - "Tie bar is not there because it is sold as a subpanel." When would the neutrals not be tied? Seems that the two neutral bus bars will be tied together in all uses whether as a main breaker power supply panel, a local sub-panel, or a remote sub-panel.
And yes, the bonding to equipment ground is what must be considered when choosing the location of the panel.

[eugene thomas]

Ya might want to find out about the grounding rods. I have heard ya not suppos to use grounding rods on sub panels as much as to use them...

[John McClanahan]

Here is my 2 cents worth. The left buss is the neutral. The buss on the right, up on the plastic is the ground. The green screw on that buss bonds that buss to the case. To isolate the case, remove the green screw. If the far right buss is used for ground wires and the green screw is removed, the grounds will not be connected to the incoming ground wire.

John

[Peter Quinn]

Did mine last year, 100A service, separate garage, ran feed in conduit from main 200A service. Professional electrician did all the connections and figuring, I did the grunt work and asked questions. Had to run two 8' grounding rods within 5' of the panel but at least 8' from each other to create a grounding field, could be run in at an angle as required. Here in New England the soil can be dense and rocky, I started on a ladder with a snow fence pounder, took maybe 5 minutes? Was told the sub panel absolutely code required to have its own ground, the rest I can't offer much with certainty. Sure is nice having good solid power in the out building though.