Garage electrical options?


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Old 03-12-14, 12:41 PM
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Garage electrical options?

Currently there is 40A double pole in main panel sending 3 wire #8 to the garage. In the garage there is a sloppy subpanel with 2- 20A breakers. There is no ground rod driven. The lighting and the some of the outlets are all spliced inside the subpanel.

The garage has many unused outlets and the only power consumed is the garage door opener. I would like to add some flood lights or a dusk till dawn on the roof of the garage to illuminate the back yard too.

What options do I have? Grounding and the many splices in the box first pop out at me...
 
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Old 03-12-14, 12:57 PM
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Are the new lights going to take more than the current amperage, in the sub-panel?
 
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Old 03-12-14, 01:13 PM
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Lights would not be a factor whatsoever. However, they would be added to the splices in the box (which needs to be cleaned up) or I would tap off an outlet for any lights.
 
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Old 03-12-14, 02:07 PM
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Is the garage attached or detached?

Splices are allowed in the panel.
 
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Old 03-12-14, 02:27 PM
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Detached. Hence my concern about grounding.

Splices are allowed? Its like 6 outlets are spliced and pigtailed to one breaker and the lighting is spliced and pigtailed to the other breaker.
 
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Old 03-12-14, 06:38 PM
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Detached Garage

Was the garage feeder installed prior to 2008? Is there any metallic (water line etc.) between the garage and the residence? Is there any ground at the garage panel? There may be no ground rod but is there a UFER ground (conductor coming out of the concrete footing and going to the panel? You said 3-#8's are going to the garage, is there also a ground wire? You can combine lights and receptacles on the same circuit. All receptacles need to have GFCI protection.
 
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Old 03-12-14, 06:47 PM
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As Bahtah was alluding to if your garage power was installed before 2008 your 3 wire feeder would be grandfathered in. Drive a ground rod (or two if there is not other ground available) and connect it to the neutral bar. Th epanel case should also be bonded to the neutral bar as this is considered the service of the garage. There should be 6 or less circuit breakers or you will need a main breaker.
 
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Old 03-19-14, 08:51 AM
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So to clarify my situation.

No ground rod. There are 3 wires coming from main panel. No ground wire however there is rigid metal conduit between the mainpanel and this subpanel.

So I need to connect ground rod to the neutral bar in the panel.

I read in a book that ground (in this case from the ground rod) and neutrals (in this case the circuits returns) should not be on the same busbar. There is not slots to add a second bar in this small panel. I assume I am grandfathered though and can simply connect the (#6 from ground rod) directly to the same busbar the circuits returns are on.

This doesn't make sense to me as then the returns from the devices in my garage will be going to the ground rod instead of back to the main panel with the neutral (part of the 3 wires from the main panel)

Please clarify.
 
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Old 03-19-14, 09:31 AM
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No ground wire however there is rigid metal conduit between the mainpanel and this subpanel.
Hopefully not buried EMT. The conduit is your ground . You would install a ground bar in the panel and un-bond the neutral if bonded. Your GEC and all grounds in the panel go to the new ground bar. If it is buried EMT best practice would be to pull a ground wire because EMT will rust out.
 
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Old 03-19-14, 03:44 PM
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A previous poster stated I was grandfathered so the ground rod can go on the neutral bus bar that is currently in the panel.

There is not a place to install a second bus bar and I don't have any directions on the panel that describes installing a second bus bar.

When you refer to "all grounds in the panel" there are no separate ground wires in the boxes. The only grounded conductors in this panel are neutrals.
 
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Old 03-19-14, 04:29 PM
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Ordinarily a 40 ampere (#8 copper) 120/140 volt feed will support six 20 amp branch circuits, three on each leg. If the subpanel won't hold that many breakers it may have been put in "temporarily" until more power was needed in the garage. Replace it with a larger subpanel if/when desired.
 
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Old 03-19-14, 04:45 PM
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Tolyn wrote:
As Bahtah was alluding to if your garage power was installed before 2008 your 3 wire feeder would be grandfathered in. Drive a ground rod (or two if there is not other ground available) and connect it to the neutral bar.

I just wanted to confirm that this is OK before I do something that might be stupid. Im assuming this means I run #8 stranded from ground rod and terminate it on the neutral bus bar.

You mentioned unbonding the busbar and I saw reference to this in a book I have.... is that necessary, and if so I am unclear on how to do this?
 
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Old 03-19-14, 04:45 PM
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There is not a place to install a second bus
Could you post a picture of the inside of the panel.
 
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Old 03-19-14, 04:48 PM
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You need a grounding electrode like a ground rod and it will not be bonded to the neutral. You may need to buy a ground bar for your panel. The other poster added that comment before we knew you had metal conduit.
 
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Old 03-20-14, 04:01 AM
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Its a general electric panel.

There would be tapped holes for a second bar correct?

If there is not, how do I proceed because I did not see anything like this inside the panel.

So to confirm, I need a second ground bar that the ground rod would attach too. The neutral bus bar would be unbounded from the enclosure if I add the second bus bar.

I am not sure how to "unbond" the netrual bus either.
 
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Old 03-20-14, 06:13 AM
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Further investigation has yielded the following:

Its a GE TL240SCU 40A 2 circuit enclosure.

It uses a GE TGK4 equipment grounding bus (which by chance I have on hand). I see one mounting hole in the back, the other is covered by the entrance cables. It might be a tight fit. I will have to drill into the wood backing plate to get the mounting screws on.

The diagram on the cover that shows the neutral bus shows 5 slots for neutral wires. A 6th slot I think had a bonding screw in it and it has been removed.

The neutral bus is not bonded. So what is the ramification here as it stands now unbounded? This is wrong obviously?
 
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Old 03-20-14, 03:13 PM
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To unbond a neutral bus bar its just that lone screw right? In the diagram it shows a bonding screw and it appears to already have been removed in my installation.....
 
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Old 03-20-14, 03:23 PM
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To unbond a neutral bus bar its just that lone screw right? In the diagram it shows a bonding screw and it appears to already have been removed in my installation.....
Yes, but you can measure the resistance from the neutral bar to the ground bar with no wires connected. It should lbe infinity.
 
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Old 03-21-14, 01:48 PM
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I tested and found (with feeder neutral still on bus bar)

I was getting a small reading when I placed my multimeter to OHMS between the ground bar and neutral bar (neutral bar had the bonding screw removed). However, my continuity function was not sounding.

When I tested between panel box/conduit to neutral bus bar I was NOT getting a continuity alarm.

However, when I tested between equip. ground bar and box/conduit I was getting continuity.

WIth the power on I was testing hot to ground (equipment ground bar) and was getting the usual 120 readings.

I have everything connected and cant disconnect everything now for further testing...

what else can I do to assure the neutral bar is definetly unbonded? There is no screw as described on the directions so I assume I am good.....
 
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Old 03-22-14, 12:32 PM
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The idea of the neutral bus bar being bonded means there would be continuity between the metal box/conduit and the neutral. correct?

Since the screw was missing, I could not get continuity between neutral bus and metal box. I installed the equipment ground bus and it has continuity with the metal box (even with light switches on the other side of the room!) .... but not with the neutral bus bar.

So jut to clarify, have I got this straight? Is there anything else I can do to assure this is safe? I don't want neutral voltage going to ground and back to the main panel.
 
 

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