sub panel question (add it to the mess of threads)

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  #1  
Old 03-28-12, 12:22 PM
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sub panel question (add it to the mess of threads)

Ok So I have been doing a great deal of searching and have come up with endless amounts of conflicting information. I will show you what I settled on and I am curious if anyone can explain why I should have done it a different way and what the purpose of that would be.

I installed a sub panel in a detached garage. The run is 100' 2/2/4 UF direct burial in a 2' trench. At the service panel (in my basement), I connected the three wires (2 hots and a neutral) . I ran these cables to the sub panel and connected them just as they are connected at the main panel. I then drove ground rods at the garage and ran a #4 copper cable to the ground rods. Because I used a 3 wire feeder I bonded the neutral and the grounds at the sub, there are no other metallic pathways between the garage and the house.

I understand that 2008nec does not allow for 3 wire feeders but when this was done I was still going off of previous code.

So my question is....Am I correct to assume that the way this is wired is functional/safe?..

Also just so I am no longer confused about the whole situation can someone confirm my thinking that in a 3 wire system the grounds and neutrals are bonded at the sub as opposed to a 4 wire feeder where the neutral and ground are isolated from one another.

I have attached a picture of my sub panel please point out any errors that you may see....

On a separate note if you are running a 4 wire feeder and the ground and neutral are bonded at the house then why would isolating them at the sub make any difference?


Also in my current setup which has been running for half a decade without problems there is no bonding screw to attach the neutral/ground bus to the panel itself, should there be?


http://i33.photobucket.com/albums/d1...13/photo-1.jpg


Edit: I am aware that I do not have a main disconnect at my sub, and I intend on installing one in the near future!
 

Last edited by budd0413; 03-28-12 at 12:42 PM.
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  #2  
Old 03-28-12, 01:57 PM
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I see a couple of problems in that pic. One, I do not see any conduit around the conductors outside the panel. The other is the use of a Square D Homeline breaker in a non Homeline panel. I don't see the bond screw or strap.
 
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Old 03-28-12, 06:59 PM
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I guess I didn't realize that conduit was required, is that a safety issue? About the breaker that doesn't match It seems to fit fine, but then again I have really no knowledge about what I'm doing, what is the regulation for having the same brand breakers? Thanks for the reply! Also what is the purpose of having the common bonded to the panel?
 
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Old 03-28-12, 07:48 PM
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It appears you have two neutral bars and the neutral is grounded, but the lack of a bonding screw means the panel box is not grounded and yes, that is a problem. Not addressing the direct burial conductors that aren't in conduit (pcboss has already mentioned this), what you have are probably type USE conductors. I don't believe type USE conductors are allowed to be used inside a building.

About the breaker that doesn't match It seems to fit fine, but then again I have really no knowledge about what I'm doing
That is obvious from the picture. The Square D breaker is not U.L. Listed for use in what appears to be a Cutler-Hammer panel. It may fit and appear to be fine, but U.L. has not tested it for use in this panel. Is it a problem? Probably not unless you would have a fire and the insurance inspector spots it.
 
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Old 03-29-12, 06:39 AM
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Thanks, I will install the bonding strap asap, what is the reason for the panel needing to be grounded? I am assuming it is in the event of a shot in the panel the circuit is completed causing the breaker in the house to trip instead of having a "hot box". I will replace the out of place breaker with the correct style. Thanks for the info.
 
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Old 03-29-12, 07:00 AM
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Correct, without a bond the metal box could remain hot and not trip the breaker. Someone now touches the can and becomes part of the circuit and could receive a shock or worse.

Individual conductors need to be in conduit in accordance with the electrical code.
 
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