I am serving two subpanels from a Square D main entrance panel (I would call it a “distribution panel” or “DP#1”) that has facilities for breaker and “pass-though” connections. These are both de-energized with a single 200 amp breaker.
So I am serving one subpanel (SB#1) in the main entrance building with a 100 amp breaker in DP#1, and another subpanel (SB#2) in a remote building with a three conductor underground cable connected to the pass-though lugs and terminating in an identical distribution panel (DP#2)currently mounted on the remote building where the connection to (SB#2) is made.
Am I clear so far?
I need to completely de-energize the underground cable and DP#2/SB#2 because I am adding an addition to the remote building which will require excavation in the area where the cable runs. I will also need to re-locate DP#2 when construction is finished. I will be able to serve temporary power to the remote building via extension cords from the main building (~50 feet).
So the question is: In the main distribution panel the two hot wires are bolted to the pass through lugs. No problem, I can de-energize those with the 200 amp entrance breaker OFF and then remove the wires from the lugs and tape them off. But the neutral is bolted to a lug up at the top, between the two always-hot lugs coming from the meter. DO I NEED TO DETACH THE NEUTRAL? Seems like I can leave that be because there is no way that neutral will ever be energized with the two hot wires detached.
By the way, this whole setup was installed by a licensed electrician with adequete wire sizing etc. and inspector has approved.
Replies
I would disconnect the neutral and tape all three wires together and position them so the would pull out easily in case the excavator hooked the underground wires/conduit. then I would remove the conduit nut from that run.
It is not unreasonable to think that a backhoe could pull the whole DP#1 off its' mounting.
SamT
Glad I asked! Although he will have a helper (might be me!) to pull the wire up as he digs.
What size hex tool should I get to loosen that lug screw? It's a recessed hex screw.
Maybe I should get a whole set.
Muh man, you're gonna have to get the electric compny involved with this to pull the meter since there is no disconnect at that level.
Samt
But the hot wires I need to disconnect are connected to the pass-through lugs on the downstream side from the main breaker, which I can turn OFF. It's just the neutral that's up at that level. Looks like the lugs up there are designed (protected on each side from the hot lugs) so you could get a tool in to loosen the hex screw on the neutral without pulling the meter. That's one of the reasons I have this set-up...so I could disconnect myself when I needed to move DP#2.
That proximity is what makes me want to leave it be, and why I haven't gone ahead and detached already.
I could be wrong, though...just don't want to be dead wrong.
OK.
I don't know the size allen you'll need, but.
Go find a new panel at the store and measure it.
You should be able to find an appropriate tool at a large electrical supply house, get a pair of rubber electricians gloves, wear rubber boots and have at it.
Just remember that I'm probably just a smart alek 12yo stealin' time at my daddy's computor and you do this at your own risk! I am not responsible for anything!!!!!
SamT
OK OK, thanks for the info and disclaimer. So you're tellin me that the neutral is NOT hot, as I believe, and the only risk I'll be taking is getting sloppy with a tool too close to the hot lugs? Oh and then moving that big stiff wire around in there.
Maybe I'll get the electrician out to do this after all. Thanks.
Maybe its hot, maybe its not... depends. its supposed to not be hot, I can tell you that.
Since you are going to get an electrician, I'll admit to being a little older tha 12yo.
SamT
It happens to be the largest one on the allen key set. 3/8" I believe. A rubber handle T wrench is the best for this.
Please be very careful.
Len
I would cut the neutral and the hot, after turning off and double checking that they really are off, near where they come into the panel. From what I gather the entire feed will need replacing so there is little sense to taking the time to save the extra length of the hots and taking time to tape them off. I might wrap a few turns of tape around the lot coming in if length remained but often cutting them off at just an inch or two is quickest. Makes sense to insulate any lengthy tails to prevent fireworks if they wander but stubs, especially when they are soon to be replaced with the new feed, are generally well behaved. When the new feed is pulled in pulling the old stubs out will be easy.
I might be tempted to keep one intact, I like to use the ground, if present, to have something to help pull in the new feed. The ground is likely to be thinner and more pliable so it is easier to use as a pull wire.
The scrap hot tails, after cutting where they enter the panel, I would remove. The neutral I would leave alone if: 1) there are neutral lugs available to receive the new feed. 2) if the abandoned neutral tail is not in the way or likely to wander. I would take care to insulate the tail where the cut was made as this end is most likely to drift into live busses or otherwise get into trouble but tucked neatly into a corner of the panel I think it is a minimal concern. If at some later date the meter was pulled removing this piece would be simple but presently it would not be my priority.
When and if you remove the neutral line going to the out building from its lug make dead sure you do NOT disconnect, damage or otherwise compromise the neutral connection to the panel. In some cases both cables will be under a single lug necessitating loosening the lug. Make sure you remake the connection from the meter. The integrity of this connection is the most important of the three coming from the meter. Loosing a main neutral connection allows voltages to drift. Fires are sometimes a result.
Thanks for your input. Perhaps I was not clear in explaining this project...let me try again.
The feeders in the the main entrance/Distribution Panel # 1 (DP#1) only need to be disconnected so I can move DP#2. So this is temporary until DP#2 is remounted and new connections made at the end of the original but somewhat shorter cable. This is the cable that is currently running from DP#1 underground supplying the remote (~50 feet) building. This is the cable that needs to be moved during construction, and it will be re-used once construction is complete.
I don't have a problem with detaching anything in DP#2 once it is completely de-energized, moving and re-mounting the panel, or in re-making those connections. Once the cable is detached from the panel and removed from the conduit, it will be coiled safely to the side until the addition is framed and sheathed. This will be sevral months. It will NOT be energized until it's complete.
Meanwhile, during construction,I still need power in the main building, so will need to turn the circuit breaker back on once I'm done with the disconnect.
My question is with the neutral feeder that provides the neutral for DP#2. It is connected to the main neutral lug at the top of DP#1 between the two hot lugs for the feeders from the meter. I would like to leave that alone for three reasons: #1...Why mess with the integrity of the all-important neutral connection from the meter, #2...that lug is awfully close to the two always-hot lugs to be poking around in there with a tool, #3...it won't have any current carrying potential once the hots are disconnected, taped and tucked away. The hots are easy because they are bolted to the pass-through strips/lugs at the bottom of the panel, which can be de-energized via the main breaker.
Does that make more sense?
Thanks again.
Edited 8/26/2003 9:28:30 AM ET by johnnyd
IMHO -
Any neutral wire that requires an allen wrench of any size, should only be removed by someone who knows what he is doing!
How 'bout sending us a picture.
I agree. I checked with the inspector, who is familiar with this setup, he said go ahead and leave the neutral connected.
Thanks, all for your advice.