Sub-panel at partially remodeled cabin

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Old 10-30-15, 11:40 AM
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Sub-panel at partially remodeled cabin

Hi all and it's great to find a forum like this. Great resource.

We recently purchased a partially remodeled cabin through foreclosure and among some of the work already completed was a new out-building and sub-panel that is in place but not connected to the main. The electrician or previous owner placed a Seimens 1125 in the out-building to use as a 120v, with (1) 20amp and (2) 15amp breakers for overhead lights, an attic fan and an outlet circuit. There is also a jumper in place between the hot lugs so that all the breakers would be active on that particular panel type with no main breaker option.

The building is approx. 55ft away and he used 2 #6 feeds coming from the main, one hot and one neutral and the hot is apparently for connection to a new 50amp breaker at the main. The pair is rolled up and tied off just outside the main panel. The ground and neutral lugs are not separated in the new sub-panel, but the cabin itself is older construction and the main has its neutrals and grounds on the same strip. There is also no ground feed from the main panel to the sub, but instead a new copper ground rod at the sub with a single solid copper feed from the rod to the ground/neutral strip.

My 2 questions are that although I recognize the older neutral/ground combined on the same main panel bars as something I've run across before, I'm now wondering if the sub-panel is supposed to match the main panel or should the neutral/ground bars still be separated at the sub?

The second question relates to the new grounding rod at the sub-panel instead of a feed back to the main panel's ground circuit. I once recall it being acceptable either way but it may have changed since. I also remember something about any ground circuit being as close in proximity to the main panel breaker as practical, but it's been so long that I may not have that recalled correctly.

Any input would be greatly appreciated. Main concern is obviously safety and although the work appears very professionally installed, I want to be certain before I actually connect the sub to the main for use in the present configuration.

Thanks in advance.
 
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Old 10-30-15, 11:54 AM
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The neutral and ground must be separated at the subpanel. It sounds like you don't have enough wires to hook up anything safely. Is there a conduit between the cabin and outbuilding? You at least need another #6 wire and a #10 ground (assuming the existing ones are serviceable).

Conversely at the main panel for the property, which is the first panel after the meter, the ground and neutral must be connected, but only at that one place. Everywhere else they must be kept separate.

Can you post some pictures of the set up? It would be helpful to see it in this case.
 
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Old 10-30-15, 12:09 PM
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If it is a to be used as a 120 volt only panel a 50 amp 2 pole breaker should be used as the jumper connection and the hot power in cable should go to one of the main lugs. As Ben said you must have a #10 ground. The ground rod is for the GEC only. You still need the #10 for the GEC. Both the GEC and EGC as Ben wrote need to go to a separate bonded ground bar. (The neutral bar must be isolated.) You don't need a main breaker or other disconnect at the subpanel if you have 6 or less branch circuit breakers.
 
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Old 10-31-15, 08:22 AM
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Thanks for the reply, Ben. A schedule 40 conduit was ran from the main panel, attached along the lower third of the exterior cabin and then underground to the out-building. The only wiring within the conduit is one black #6 and one white #6 stranded. At the sub-panel, the intended hot line is attached to one of the lugs with a jumper #6 wire connecting to the second lug. The panel lid provides a schematic describing this jumper wire if a main breaker is not used strictly if the panel is wired as a 120v service only. The white #6 neutral is attached to the ground bar along with all of the neutrals and grounds from the circuits. The single solid copper ground is also attached to that bar and then down to the copper rod.

I'll try and get some photos of it. No cell service here though and I'll have to get a data cable or find my card reader to get them onto the computer. You state that I need at least one additional #6 and the #10 ground. The #10 ground is clear to me, but what is the purpose of the 3rd #6 wire? (unless you are referencing it based upon the 50amp double pole at the main panel intended for supply to the out-building.) At the main, it appears as a 240 supply, but I see nothing at the panel that was intended to provide a 240 line and the line supply and jumper was placed as described in the panel lid schematic as strictly useable for a 120v panel supply. I just assumed, maybe incorrectly, that the installer only intended to use one pole of the 50amp double at the main to supply the out-building. Since the 2 #6 wires were coiled and taped outside the panel, I can't be sure of his actual intentions though.

By your description, it sounds like this setup is not ready to be energized at all and I'm fine with that.

So if the panel is strictly for a 120v supply, what again is the total number of wires I need from the main to the sub and where should they terminate in order for this arrangement to be safely wired and operable?

Thanks once again!
 
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Old 10-31-15, 08:27 AM
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Thanks, Ray. I had assumed that the installer followed the schematic inside the lid panel that depicted a jumper wire of the same gauge between the lugs for 120v service only. Doing so gave a total of 4 circuit breaker slots, wherein a main double pole would leave only 2 slots. Everything else is clear to me with the exception of the additional #6 that Ben mentioned.

I think I can make it all work if I get some clarification on that wire. The neutral/ground bar separation is clear to me.

Thanks!
 
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Old 10-31-15, 08:42 AM
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but what is the purpose of the 3rd #6 wire?
Normally subpanels are connected as 120/240 not 120. That gives more available power for 120 circuits and provides the option of 240 if ever needed.
So if the panel is strictly for a 120v supply, what again is the total number of wires I need from the main to the sub and where should they terminate in order for this arrangement to be safely wired and operable?
You need two #6 and one #10. How you connect the #6 hot is not a given. In most cases the terminal lugs on the panel are not rated for two wires so you can't just put the jumper and hot to the lugs because that would be two wires under one lug. You need to check if your subpanel is listed for two wires.

If it isn't rated for two wires under a lug one way to do it would be to just use one half the panel. That is simplest just connect the power to one bus bar then all the even or odd spaces would have power depending on which lug you connected to.

You could attach two pigtails to the hot and one pigtail to each lug.

You could put the jumper across the lugs and back feed the panels with a single pole 50 amp breaker. That breaker would need a hold down which they probably don't make so you'd need to use a double pole breaker and connect to one side. (This would provide the code required disconnect if you have more then 6 branch circuit breakers.)

You could use a double pole 50 amp breaker for your jumper and connect the hot to either lug. That way you would have power to all the spaces.

Are you beginning to see why since you need to pull at least one more wire just pull two?
 
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Old 10-31-15, 11:58 AM
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Got it and thanks so much once again. I've never seen a box wired this way, so much smarter to ask someone than simply finish another person's work that may or may not be to code, or worse yet represent a high risk factor.

take care
 
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Old 11-02-15, 08:06 AM
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The very least you need is the #10 ground. It can be green insulated or bare copper. The additional #6 is the typical way of installing a subpanel to provide for 240V service, but is not strictly required if you only need to use 120V. If you stick with a single hot wire, you'll need to jump that hot to both sides of the subpanel or only use every other set of slots. I'd probably get a split bolt connector rated for three #6 copper wires, and make two short #6 jumpers from the incoming hot to each of the panel hot lugs. You then wrap the whole thing up with a couple layers of good heavy electrical tape.

Technically speaking the neutral wire should be solid white insulated, however it is fairly common practice to use black wire and wrap the last foot or so with white electrical tape so it is clearly marked as the neutral wire.
 
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Old 11-02-15, 11:03 AM
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Clarification:

You need the #10 to bond the equipment grounds of the two panels together.

You also need a ground rod at the subpanel, connected to the equipment ground. The purpose of this is to keep the earth potential close to the equipment ground potential in the vicinity of the outbuilding.
 
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Old 11-05-15, 03:47 PM
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Sub-Panel @ Out-building

Thanks to all of you for your assistance. Separated the neutral bar from the ground bar at the sub panel and attached the wires accordingly. Added a #10 green coated wire for ground between the two panels, used 1 #6 hot leg for 120v and the second #6 for the neutral, then ran the solid copper equipment ground to the rod. Hooked up the hot leg at the main panel to one of side of the double pole 50amp, the white #6 to neutral and the green #10 to ground.

Works perfectly as a 120v sub panel and looks to be a safe system.

Thanks again!!!
 
  #11  
Old 11-05-15, 06:11 PM
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Thanks for letting us know how it came out.
 
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