Electrical Question

[bones1]

I have a similar setup to one of my sheds.Just 12/2 run 100ft to a breaker box mounted in the shed with a 8ft ground rod I was told I needed attached to the metal breaker box.Threw the bonding screw away .Is this safe like this?

 

[Timber]

I am pretty sure that by code the sub panel needs to be grounded back to the main panel, only a main panel can have the ground rod attached to the ground bus. Otherwise you would have a ground loop (bad things can happen).

This is the way it was explained to me by my electrician friend, when I tried to hook my old barn up to my new barn (new 200A service there), I was going to ground the old barn using the existing ground rods and he told me that was a big NO NO. So, I ran 2G wire (2 hots, 1 N, 1 G) for a 100A subpanel.

You might want to check the NEC book to make 100% sure. If you do go the 10/2 route, you will have to put colored tape on the white wire as it is no longer a neutral wire, put something like red electrical tape on both ends. Personally I would just run the 10/3 or something bigger depending on your load requirements.

Derek

You might be right I have to look it up in my book, now I'm just curious

 

[mudcat]

I see I have to consult the big book on code but I'm sure the ground rod at the sub panel is the neutral. Even if you cut into the cable in the ground it will trip out at the main panel because your feed to a sub panel starts at a breaker that is grounded. That said if you reach down and grab the cable regardless if it 10/3 or 10/2 with a bare hand your gona take the hit. same with your grounded compressor. Electricity will take the shortest path to ground. in this scenario that would be you, also if I may add if you hit a cable and grab it with a bare hand Shame is on You. You are correct that lightning will follow this path but that is not the only reason to ground your panel. In order for electricity to work properly in the US anyway neutral/ground is designed in all are tools, appliances, and ex cetera

I believe you misunderstood the point of my post. Please read it again. My example was not about cutting the power feeding the building. Ever notice that there are THREE slots on a recepticle; The one on the left is grounded, the one on the right is hot,and the bottom one is grounding.

 

[Timber]

I believe you misunderstood the point of my post. Please read it again. My example was not about cutting the power feeding the building. Ever notice that there are THREE slots on a recepticle; The one on the left is grounded, the one on the right is hot,and the bottom one is grounding.

LOL you getting testy with me, Hold on I know I have a can of WOOP_*** around hear somewhere. LOL I have to consult the book because I simply can't remember. There is code and that is the law. there really is no dispute over that. Hey I admit I could be wrong, I know a lot of things just not everything, well almost everything LOL

 

[mudcat]

I have a similar setup to one of my sheds.Just 12/2 run 100ft to a breaker box mounted in the shed with a 8ft ground rod I was told I needed attached to the metal breaker box.Threw the bonding screw away .Is this safe like this?

No. It is not safe.

 

[hilld]

I think I might have found the answer. It appears that a seperate ground rod is required at the other building, however, a 3 conductor + ground service feed must be used.

Here is a diagram of the particular section of the NEC.

The following text is quoted from: http://www.iaei.org/subscriber/magazine/03_f/03_f_threechiefs.htm

Subpanel located in or on a building or structure separate from the service equipment
Section 250.32(B), Grounded Systems, contains provisions which result in two different ways to connect grounding and bonding conductors at a subpanel located in or on a building or structure supplied from a separate building or structure. Figure 2 illustrates 250.32(B)(1), the first way to wire a subpanel. The following are key points for this installation:

1. The subpanel is located in or on a building or structure supplied from a separate building or structure.
2. The subpanel is supplied by a three-wire plus ground feeder (two ungrounded (hot) conductors, one grounded [neutral] conductor and one equipment grounding conductor).
3. The neutral bus is isolated from the subpanel by insulating material.
4. A grounding electrode is required. Existing electrodes must be bonded to the equipment grounding terminal bar by a grounding electrode conductor sized according to Table 250.66 and based on the largest ungrounded (hot) conductor of the feeder (note the change from the 1999 NEC, where Table 250-122 was referenced).
5. Water and gas pipes are also required to be bonded to the equipment grounding terminal bar. See Sections 250-104(A)(3) and (B) for the bonding conductor size.
​

 

[mudcat]

LOL you getting testy with me, Hold on I know I have a can of WOOP_*** around hear somewhere. LOL I have to consult the book because I simply can't remember. There is code and that is the law. there really is no dispute over that. Hey I admit I could be wrong, I know a lot of things just not everything, well almost everything LOL

You might want to read these:
Article 100 Definitions
Article 200 Use and Identification of grounded conductors
Article 300 Wiring methods
Article 250 Grounding
It is easy to misinterpret the code. But this is basic electricity. I just don't like someone being given unsafe advice.

 

[mudcat]

I think I might have found the answer. It appears that a seperate ground rod is required at the other building, however, a 3 conductor + ground service feed must be used.

Here is a diagram of the particular section of the NEC.

The following text is quoted from: http://www.iaei.org/subscriber/magazine/03_f/03_f_threechiefs.htm

Subpanel located in or on a building or structure separate from the service equipment

Section 250.32(B), Grounded Systems, contains provisions which result in two different ways to connect grounding and bonding conductors at a subpanel located in or on a building or structure supplied from a separate building or structure. Figure 2 illustrates 250.32(B)(1), the first way to wire a subpanel. The following are key points for this installation:

1. The subpanel is located in or on a building or structure supplied from a separate building or structure.
2. The subpanel is supplied by a three-wire plus ground feeder (two ungrounded (hot) conductors, one grounded [neutral] conductor and one equipment grounding conductor).
3. The neutral bus is isolated from the subpanel by insulating material.
4. A grounding electrode is required. Existing electrodes must be bonded to the equipment grounding terminal bar by a grounding electrode conductor sized according to Table 250.66 and based on the largest ungrounded (hot) conductor of the feeder (note the change from the 1999 NEC, where Table 250-122 was referenced).
5. Water and gas pipes are also required to be bonded to the equipment grounding terminal bar. See Sections 250-104(A)(3) and (B) for the bonding conductor size.

​

THANK YOU!

 

[Timber]

Well there you go everything is in black and white on the pages of a book

 

[FarmTracRay]

Lot of info here for sure. The wire has been in the ground for several years, I hardly ever used the lights in shed since my wife took it over and filled it with storage boxes. Wire connected to light switch in garage. Disconnected for now. I just realized I have a second 12/3 wire buried (thats a total of 2 12/3 wires) which I was going to connect to a switch in garage for external light on old shed, never got it done for some reason. Will power off of 100 amp service in my garage. Guess they will start on shed this coming Tuesday if the rains are done for a while. I am leery about splicing below ground, may just leave the buried cable where it is for now (till copper gets even more rediculous) and power shed by generator (Y2K with bout 40 hours on it). I don't really plan on doing much down there. Keeping the tractor, four wheelers, mowers, etc outta the yard, clearing the junk outta the garage. All I 4c is lights, maybe a battery charger 4 dead bats, or small comp for flat tires. It will be gravel floor. Have a freezer and fridge in garage, 110 5 HP air compressor, no major power tools. Can I just run the lights and receptical in pole barn from a switch in the garage, maybe 2 switches.