DIY Home Improvement Forum banner

Subpanel conductors

6K views 44 replies 11 participants last post by  downunder 
#1 ·
Hello all,

I have an unattached tool shed/ "shop" with a 240v subpanel. A neighbor helped run this for me and sugggested the 240 in case I ever wanted to run a bigger air compressor or something.

At the present all of the few loads are on one circuit. Just an overhead light and a couple of outlets. I want to run a couple of extra outlets outside and thought I would put them on a second circuit. After opening the subpanel box, I am a little confused. See photos.

There is a black, white and ground coming from the main panel in the house. Black and white are both hot. The ground goes to what looks like to me an isolated bus.

I'm just not sure this is exactly how it should be and hoped the wealth of knowledge here could throw something in.
 

Attachments

See less See more
2
#33 · (Edited)
A ground rod is not for lightening protection

and to nap, i seem to have completely missed the fact that he is at a detached building with this sub panel, I just looked at his pictures and fired away, i should of read the post. THAT BEING SAID :icon_cheesygrin: you are right, you need the ground rod outside to the equipment grounding bar which by the way is still not bonded. don't flame me bro!
 
#40 · (Edited)
are you for real right now? if anybody thinks that the two ground rods outside connected to somebodies main service with a #6 wirer will protect them from lightening strikes on their house needs to have there head examined. I'm not trying to start anything either, but a ground rod is not for lighting arrest. A lightening arrest system is an engineered grounding grid system with lightening rods.
 
#5 · (Edited)
Man, that was quicker than waiting on customer service at some companies!!!!

This was done about 15 years ago. Until very recently, my knowledge of AC was replacing an outlet occasionally- put the black where the black was and the white where the white was.

I suppose the forethought of preparing for 220 was good in some regards. However, I don't really have any expectation of doing that. There has been no trouble at all of breakers tripping or anything so I have really had no reason to even look in the sub panel.

How would it work to move the white to the neutral bus in the main panel in the house and in the sub panel also? That way I would have a correct (?) 110 circuit with that regard.

I haven't looked in the main panel yet, but would I need to have the bare ground from the sub panel going to the ground or neutral in the main panel or does it matter? I had considered adding a ground rod at the shop. Would that be a better way to ground from there or should I leave the bare ground from the shop to the main panel?


Oleguy, it's about 50 ft.
Thanks all,
Richard
 
#8 ·
This type of setup was allowed years ago, but not now. If it was inspected it could remain, if not needs to be corrected. This is all up to rules used in your area.The panel can be correct by running a new wire for a neutral or just making this a 120 panel.
The white is not required to be remarked, also any wire under size #6 is not to be marked per NEC
 
#12 ·
This type of setup was allowed years ago, but not now. If it was inspected it could remain, if not needs to be corrected. This is all up to rules used in your area.The panel can be correct by running a new wire for a neutral or just making this a 120 panel.
The white is not required to be remarked, also any wire under size #6 is not to be marked per NEC
Conductors in a cable can be re-identified even if smaller than #6.

A three wire feeder was allowed before, but it did not allow the bare ground as a neutral.
 
#9 ·
If you are OK with only having 120 in the shop, it can be corrected fairly easily. Remove the white wire at both ends and connect to the neutral buss on both ends. Install a new ground bar in your sub for the bare ground. Install and connect 2 ground rods to the new ground bar. Connect the black feeder to both of the hot lugs in the sub. Mark the sub 120 Volt Only

Also, install the lock nuts and close the open hole in the box.

What size are you feeder wires? This will determine the largest breaker you can feed with in the main.
 
#10 ·
If you are OK with only having 120 in the shop, it can be corrected fairly easily. Remove the white wire at both ends and connect to the neutral buss on both ends.
I already thought of and asked that:

How would it work to move the white to the neutral bus in the main panel in the house and in the sub panel also? That way I would have a correct (?) 110 circuit with that regard.
I don't follow how to connect one black wire to two lugs.

With otherwise correct grounding, what are the issues with leaving the ground connected to the house main panel as opposed to installing a new ground at the shop? On one hand I have heard that it is better to have the ground as close as possible and on the other hand I have heard to always tie back to the service ground.

This is in a utility building with electric for lights, light power tools, i.e. Skil saw, drill, etc. While I am usually picky about most things, compared to proper grounding I don't really think that missing a locknut is that big of a deal.
 
#13 ·
jbfan,

I don't think I have room for another breaker in this panel.

Just for asking, what does the size of the wire matter whether it needs to be re-identified? Seems like you would want to do that anyway if a white is going to be hot.


FWIW-
I read once that Albert Einstein was asked for his phone number. He replied that he would have to look it up because he didn't bother with remembering information that he could find somewhere else. Thanks to all the help here, I'm feeling smarter already.:thumbup:
Thanks guys!
 
#17 ·
If it's worth doing, it's worth doing right. If you wouldn't put your name on it, it ain't done right!
Well, "it ain't done right". It wasn't done right for 15 years ago. What you need to do to "fix" it depends on what you want the outcome to be. Most of the advice you have been getting has been not just how to make it work, but how to make it safe and comply to NEC code. If it were mine, or if I was doing it for you, I would first determine what the end result is to be. Then "fix" it accordingly.

In any case it should be corrected to at least the code requirements at the time it was installed.
 
#19 ·
subpanel

Cable assembly

The white conductor within a cable can be used for the ungrounded conductor if permanently reidentified at each location where the conductor is visible to indicate its use as an ungrounded conductor. Identification must encircle the insulation and must be a color other than white, gray, or green
 
#23 · (Edited)
A. My sig is my sig. My standards may or may not be those of a third party, so since I didn't do the install, I don't see what one has to do with the other at all.
B. Didn't say I wanted to "fix it" or "make it work." It already works- has for years.
C. I haven't asked for how to fix it to a specific end result.
D. And it seems silly to me to go to the trouble to make a repair to standards which are 15 years old and outdated. Or, just plain stupid.

My thread, I can flame if I want to.

To those who have asked constructive questions:

The cable is buried in pvc conduit. Presuming that my meager skill with a fishtape would suffice, I might could pull a neutral conductor through the several 90's.

Right now, I don't know what the exact wire gauge is. Nothing is on the length that is in the panel and I can't see the outside jacket of the cable but I would guess maybe a 6 stranded.

The house panel has a two pole 30 amp.


I'm just not sure this is exactly how it should be and hoped the wealth of knowledge here could throw something in.
Or, put another way, I know a little more than I did years ago. In MY OPINION it looks like things could have been done differently and so I have solicited the wisdom of those on this site who have MUCH more experience and knowledge than I for whatever suggestions might be made that could reasonably make this safer and perhaps more functional. Since I have had no problem with circuit breakers tripping, etc. for this many years I have had no reason to suspect a problem. Now that I am aware of this, it seems prudent to at least investigate some remedial action.
 
#24 ·
This is wrong on so many levels, first off it looks like your feeding this with a 6/2. using the white wire as b phase and then running the ground to an isolated ground bar which is being used for a neutral too! You need to run a 6/3, put black and red on the A and B phases, put the neutral on the isolated ground bar, then install a new ground bar that is bonded to the can only and remained isolated from the neutral and land the ground wire from the 6/3 to that bar. sharing a neutral and a ground on a sub panel is bad because the unbalanced load on your branch circuits between phase A and B gets brought back to the main via the neutral, in this case your don't have a correct path to to the main panel board causing a different in potential to ground which WILL cause a serious safety risk
 
#25 ·
If that wire is indeed in conduit end to end, just pull it out and pull the proper 4 wires for the 240v circuit. Of course you have to add a grounding buss and un-bond the neutral in that sub, then install a grounding rod.
 
#30 · (Edited)
right it's a main lug panel( a panel with no main breaker) so all grounding needs to go back to the main panel. It's hard to explain, but basically you can't have 2 sources to ground because it causes a difference in potential between the two, which can and will cause safety risks. it's right in article 250 you typically pound two rods at the MAIN service as a supplemental grounding electrode, or the primary if no cold water pipe is present. sitting through countless hours of boring grounding classes has done me good.



just to add, this is straight from 2011 NEC 250.2

Effective Ground-Fault Current Path. An intentionally
constructed, low-impedance electrically conductive path designed
and intended to carry current under ground-fault conditions
from the point of a ground fault on a wiring system to
the electrical supply source and that facilitates the operation of
the overcurrent protective device or ground-fault detectors on
high-impedance grounded systems.
 
#32 ·
right it's a main lug panel( a panel with no main breaker) so all grounding needs to go back to the main panel. It's hard to explain, but basically you can't have 2 sources to ground because it causes a difference in potential between the two, which can and will cause safety risks. it's right in article 250 you typically pound two rods at the MAIN service as a supplemental grounding electrode, or the primary if no cold water pipe is present. sitting through countless hours of boring grounding classes has done me good.
while it's an MLO, it doesn't change a thing. Being an MLO does not alter the physics involved or the code involved.

since you are so convinced of this, please cite the exact code section you believe requires what you are stating. Then I'll post the section that makes your irrelevant.

aw heck, I've never been good at keeping a secret. Check out 250.32(A)
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top