Detached shop electrical panel replacement

[Pressingonward]

I have a detached pole building built in 1975, and the current sub-panel is too small and is definitely not code compliant (to any year of code...) I'm looking to add a few circuits in the shop but have no room in the current panel to do so, so I'd like to replace the current panel and address the code issues at the same time. I'm not looking to bring it up to current code unless I absolutely have to, and we're not planning on staying at this property for too much longer so I'd like to keep cost and effort to a minimum.

The shop is fed by 3 wire (hot, hot, and neutral) #6 aluminum underground in steel conduit, and is on a 50 amp breaker in the main panel. Distance from panel to subpanel is approximately 75 feet. From what I read the 50 amp breaker is OK with #6 AL as long as the insulation is rated for 75c...I'm assuming that's the case for now and I can take a closer look at the wire to confirm later. I do expect I'll be pulling close to max load every once and a while. Conduit size is 1 1/4" (for reference in case I need to run new wires)

I know current code requires 4 wire connections to detached structures, but I think 3 wire is OK since it was put in service in 1975? However, I read somewhere that metal conduit isn't allowed - is that correct, and if so is it a serious safety concern? I don't suppose it could be used as the ground connection since there isn't a separate ground wire?

In the shop subpanel they wired all of the neutrals and grounds to the same bus bar, which I know is not correct by current code. There are no grounding stakes or anything - the neutral feed from the main panel is connected to the neutral/ground bus bar. If I can stick with the existing feed wires (3 wire), then the new panel should get two grounding stakes to feed the ground bar, the neutral wire to the neutral bus bar, and the two should be unbonded - is that correct?

The other fun thing going on with the existing wiring is that someone tapped into this subpanel to feed another subpanel. Since there was no room, they stuck the #6 copper wires into the main lugs along with the #6 aluminum supply wiring, so there is no breaker on the secondary sub panel feed wires except for the 60A breaker feeding the first subpanel. The big issue is they didn't run a common or a ground to the secondary subpanel - just two hots in a direct burial cable that runs another ~75 feet to the secondary subpanel. There must be a grounding rod at the second subpanel because it's being used for 120v circuits - I haven't looked closely yet.

Clearly this secondary subpanel needs a neutral run to it at a minimum. If I can stick with 3 wire to the first subpanel then I assume I could stick with 3 wire to the second? Does the secondary subpanel need the same ground setup as the first subpanel (2 ground rods, neutral and ground unbonded)? How dangerous is it to be using a grounding rod for a neutral like it's currently set up? Wondering how urgent it is to fix that issue since I'll need to dig a new trench and run wires.

Sorry for the long post but wanted to be thorough. The current panel is a GE panel as are the ones in the house. GE panels and breakers are lower cost than the other ones out there - any reason not to go with a GE panel for the replacement?

Here's some pictures of the current disaster for your viewing pleasure:

 

[yatg]

I know current code requires 4 wire connections to detached structures, but I think 3 wire is OK since it was put in service in 1975? However, I read somewhere that metal conduit isn't allowed - is that correct, and if so is it a serious safety concern? I don't suppose it could be used as the ground connection since there isn't a separate ground wire?

3 wire is grandfathered as long as you don't have any other grounded paths (phone, cable, metal water lines, etc) between the house and the shop.

If you have continuous metal conduit between the panels you can use it for a ground.
Feed conduit looks like EMT. 50 year old EMT underground is probably no bueno.
You might get lucky and its RMC and somebody used an EMT terminal adapter on it.
Need to verify what type of pipe it is and test for continuity between the house and shop to determine if you can possibly use it for the ground.

If you're going to switch out the panel, you really should do it right and upgrade to a 4 wire feed.

In the shop subpanel they wired all of the neutrals and grounds to the same bus bar, which I know is not correct by current code. There are no grounding stakes or anything - the neutral feed from the main panel is connected to the neutral/ground bus bar. If I can stick with the existing feed wires (3 wire), then the new panel should get two grounding stakes to feed the ground bar, the neutral wire to the neutral bus bar, and the two should be unbonded - is that correct?

3 wire feed, keep the neutral and ground bonded. Yes to the ground rods, connected to the common neutral/ground bus.

4 wire feed, separate neutral and ground.

 

[Pressingonward]

Thanks for the detailed reply, I appreciate it.

It is EMT. If I upgrade to a 4 wire feed what do I do about the EMT creating an alternative ground path (bad as that ground may be)? I suppose I could cut it off at ground level in the shop and stick on a piece of PVC conduit to break the ground path - does that sound like a reasonable solution?

I can check continuity if needed, but you're probably right that it's going to be pretty corroded underground...hmm, that makes me worried that running a new wire/wires through it might not be as easy as I was thinking it would be if it's collapsed anywhere or has a root going through it.

 

[wyliesdiesels]

I have a detached pole building built in 1975, and the current sub-panel is too small and is definitely not code compliant (to any year of code...) I'm looking to add a few circuits in the shop but have no room in the current panel to do so, so I'd like to replace the current panel and address the code issues at the same time. I'm not looking to bring it up to current code unless I absolutely have to, and we're not planning on staying at this property for too much longer so I'd like to keep cost and effort to a minimum.

if you upgrade the panel, it will have to be brought up to current code.

The shop is fed by 3 wire (hot, hot, and neutral) #6 aluminum underground in steel conduit, and is on a 50 amp breaker in the main panel. Distance from panel to subpanel is approximately 75 feet. From what I read the 50 amp breaker is OK with #6 AL as long as the insulation is rated for 75c...I'm assuming that's the case for now and I can take a closer look at the wire to confirm later. I do expect I'll be pulling close to max load every once and a while. Conduit size is 1 1/4" (for reference in case I need to run new wires)

I know current code requires 4 wire connections to detached structures, but I think 3 wire is OK since it was put in service in 1975? However, I read somewhere that metal conduit isn't allowed - is that correct, and if so is it a serious safety concern? I don't suppose it could be used as the ground connection since there isn't a separate ground wire?

3-wire was code permissible as long as there were no parallel metallic pathways. The conduit between the panels is considered one such pathway especially considering the neutral bus is bonded. yes this is a safety concern because neutral return current can and will flow on this conduit.

yes this conduit can be used as the EGC however its integrity could be compromised so its not a good idea, especially considering how old it is

In the shop subpanel they wired all of the neutrals and grounds to the same bus bar, which I know is not correct by current code. There are no grounding stakes or anything - the neutral feed from the main panel is connected to the neutral/ground bus bar. If I can stick with the existing feed wires (3 wire), then the new panel should get two grounding stakes to feed the ground bar, the neutral wire to the neutral bus bar, and the two should be unbonded - is that correct?

yes you will need 2 grounding electrodes and the neutral bus will need to be unbonded. you will need to check if the metallic conduit is intact. you will also need to add a ground bar and move any ground wires over from the neutral bar.

The other fun thing going on with the existing wiring is that someone tapped into this subpanel to feed another subpanel. Since there was no room, they stuck the #6 copper wires into the main lugs along with the #6 aluminum supply wiring,

this will need to be removed and changed to a breaker feed.

so there is no breaker on the secondary sub panel feed wires except for the 60A breaker feeding the first subpanel. The big issue is they didn't run a common or a ground to the secondary subpanel - just two hots in a direct burial cable that runs another ~75 feet to the secondary subpanel. There must be a grounding rod at the second subpanel because it's being used for 120v circuits - I haven't looked closely yet.

a ground rod is a poor conductor thru the earth for neutral return current and this creates a potential for shock so this really needs to be replaced

Clearly this secondary subpanel needs a neutral run to it at a minimum. If I can stick with 3 wire to the first subpanel then I assume I could stick with 3 wire to the second? Does the secondary subpanel need the same ground setup as the first subpanel (2 ground rods, neutral and ground unbonded)? How dangerous is it to be using a grounding rod for a neutral like it's currently set up? Wondering how urgent it is to fix that issue since I'll need to dig a new trench and run wires.

nope you cannot install 3-wire feeders anymore. you should run 4-wire. yes it is dangerous to use the grounding electrode as a neutral conductor.

Sorry for the long post but wanted to be thorough. The current panel is a GE panel as are the ones in the house. GE panels and breakers are lower cost than the other ones out there - any reason not to go with a GE panel for the replacement?

what brand/model panel do you have in the house?

 

[wyliesdiesels]

3 wire is grandfathered as long as you don't have any other grounded paths (phone, cable, metal water lines, etc) between the house and the shop.

the conduit between the panels would be considered one such pathway and therefore you cant have a 3-wire setup

If you have continuous metal conduit between the panels you can use it for a ground.
Feed conduit looks like EMT. 50 year old EMT underground is probably no bueno.
You might get lucky and its RMC and somebody used an EMT terminal adapter on it.
Need to verify what type of pipe it is and test for continuity between the house and shop to determine if you can possibly use it for the ground.

If you're going to switch out the panel, you really should do it right and upgrade to a 4 wire feed.

agreed. no way would i trust that old conduit.

3 wire feed, keep the neutral and ground bonded. Yes to the ground rods, connected to the common neutral/ground bus.

4 wire feed, separate neutral and ground.

he cant keep it as a 3-wire feed due to the metallic conduit.... this conduit will have neutral current on it since the neutral bar is bonded.... it needs to be fixed.

 

[wyliesdiesels]

Thanks for the detailed reply, I appreciate it.

It is EMT. If I upgrade to a 4 wire feed what do I do about the EMT creating an alternative ground path (bad as that ground may be)? I suppose I could cut it off at ground level in the shop and stick on a piece of PVC conduit to break the ground path - does that sound like a reasonable solution?

nothing wrong or problematic with an alternate ground pathway on a 4-wire feed with a wire EGC as long as the neutral bar isnt bonded. the issue is with neutral return current not a ground pathway.

just upgrade the feed to 4-wire and unbond the neutral bar and it will be fine.

I can check continuity if needed, but you're probably right that it's going to be pretty corroded underground...hmm, that makes me worried that running a new wire/wires through it might not be as easy as I was thinking it would be if it's collapsed anywhere or has a root going through it.

yup you might have to trench and put new conduit in

 

[Pressingonward]

Thank you @wyliesdiesels for the additional input, I appreciate it! That all makes sense and I think I understand what needs to be done now.

what brand/model panel do you have in the house?

The house has a GE panel and another subpanel right next to it...though now that I look at them closer I'm not positive how they're wired as I don't see a breaker from what I've always assumed is the main panel to feed the second panel...judging by the size of the loads fed by the subpanel it must be fed directly off the main breaker in the first panel if I had to guess. Either that or it's tied directly to the power meter outside, but I'm pretty sure the one labeled "main breaker" shuts off everything including the second panel...been a few years since I've had to flip it so my memory is hazy.

Main panel (?)





House subpanel (?)

 

[theoldwizard1]

3 wire is grandfathered as long as you don't have any other grounded paths (phone, cable, metal water lines, etc) between the house and the shop.

Typically not if you are doing an upgrade, like a load center replacement.

 

[Bert_]

Around here we would NOT be required to upgrade to 4 wire if only changing the panel.

A 3 wire feed with a bonded neutral was a compliment install in the 70's. You MUST bond neutral and ground if you have a 3 wire feed.

I doubt the EMT conduit goes any farther than a foot into the dirt. The wire is most likely direct bury.

 

[wyliesdiesels]

A 3 wire feed with a bonded neutral was a compliment install in the 70's. You MUST bond neutral and ground if you have a 3 wire feed.

it wasnt if there was metal conduit connecting the panels

 

[PCustoms]

it wasnt if there was metal conduit connecting the panels

Forgive the dumb question, but if it was proper metal conduit, why couldn't that act as the ground, then you'd only need 2 hot and a neutral?

 

[Bert_]

it wasnt if there was metal conduit connecting the panels

I realize I'm making an assumption. But I'm thinking the metal conduit is just a sleeve where it comes out of the dirt.

 

[wyliesdiesels]

Forgive the dumb question, but if it was proper metal conduit, why couldn't that act as the ground, then you'd only need 2 hot and a neutral?

It can but then the neutral bus needs to be unbonded which in the OPs case isnt

If the conduit he has is in tact panel to panel then neutral return current is flowing on the conduit

 

[sparky 1971]

About the only thing I remember from the 2008 code update class was the exception for the new at the time four wire feeder rule. The instructor told us that was explicitly there for installing a new panel at an older building. Right or wrong, that's what I have always followed and haven't been questioned on it yet.

And if I wasn't a cheapskate I'd be willing to bet that EMT is nothing more than a sleeve. Even if it wasn't originally, it is now cut there ain't nothin left of it below grade.