3-wire Subpanel in detached

[TylerRNEMT]

Hi everyone!

I currently have a small 8 circuit subpanel in my detached that I've quickly outgrown. I am going to be installing a mini split in the next month or so and realized I was going to have to swap out the existing subpanel for a larger capacity panel. I went ahead and bought a 20 circuit 100 amp panel and starting looking into the existing set-up a little before tackling the exchange and found something a little unexpected.

The existing panel is fed by 3 separate 2awg feeds: (2 hot and a neutral). There is no ground wire run from the main panel to the detached. So I thought ok.... maybe instead of isolating the ground bar like it should have been they bonded to the neutral bar..... but nope..... It appears they installed a separate ground bar in the subpanel and ran the appropriate circuit grounds to this.... but there is no ground wire running to this bar and it is not bonded to the neutral bar in any fashion.

Here is a picture... I know the bottom of the ground bar isn't visible, but I can assure you there is no ground attached. Any advice on where to go from here. There appears to be PVC conduit at both ends currently but I'm not sure I'll be able to pass another separate ground through as it doesn't appear to be a very straight shot.



Thanks for any input!

-Tyler

 

[wyliesdiesels]

yeah neutral bar shouldve been bonded..... but thats moot now

since you will be upgrading the panel, you will need to bring it up to current code, which is 4-wire with isolated neutral.

also doesnt appear to be a larger copper wire for the GEC going to grounding electrodes.... no way this wouldve passed code inspection even pre-2008 code cycle....

other potential issue is that feeder wire may be URD which isnt allowed inside the structure

can you find labeling on the feeder cable anywhere?

you will need to run an EGC back to feeding panel(or new feeder), install 2 grounding rods, and run the GEC from the rods into the new panel.....

 

[TylerRNEMT]

yeah neutral bar shouldve been bonded..... but thats moot now

since you will be upgrading the panel, you will need to bring it up to current code, which is 4-wire with isolated neutral.

also doesnt appear to be a larger copper wire for the GEC going to grounding electrodes.... no way this wouldve passed code inspection even pre-2008 code cycle....

other potential issue is that feeder wire may be URD which isnt allowed inside the structure

can you find labeling on the feeder cable anywhere?

you will need to run an EGC back to feeding panel(or new feeder), install 2 grounding rods, and run the GEC from the rods into the new panel.....

This is exactly what I was expecting but hoping not to hear..... You're correct forgot to mention the part about no grounding rods either..... SMH...... Guessing this work was DIY done by the previous home owner and no inspection was done at the time of install.

 

[yatg]

The feed wires are in a clamp. If you have conduit, why doesn't the conduit extend to this panel? Are the wires loose behind the wall?

 

[TylerRNEMT]

The feed wires are in a clamp. If you have conduit, why doesn't the conduit extend to this panel? Are the wires loose behind the wall?

The 3" conduit comes up through the concrete in the corner of the garage below the subpanel and elbows into the wall.... I'm assuming the wires are bare inside the wall from this elbow to the subpanel.

 

[Innovate1]

As you are finding out those are pretty big, obvious issues. If the conduit is 3" there is plenty of space for another conductor IF (and that's a big if) the conduit runs between buildings. Since they ran individual conductors in the wall they may have done the same with the buried wires. You need to figure out where the conduit ends on both ends of the run. If it does run underground then you just need to fix where it is in the wall without conduit. You could put a box at the end of the conduit and convert to multiconductor cable that is allowed to be run without conduit. Or run the conduit to the box. It can be much smaller. They must have had some 3" as that's way oversize for what was needed. You mentioned "elbow" - that sounds like it could be a plumbing fitting rather than a conduit fitting. Got some pics of the conduit?

 

[mike93lx]

Tear it all out and start over. Good chance to make sure it is done properly. A 3" conduit is huge. Does that run the whole way or is it just the stub out?

 

[sparky 1971]

It's probably a 2-1/2" conduit which is roughly3" across the outside. 3" is 3-1/2" across and would have to perfectly placed before concrete in order to fit in a 2X4 wall. It's also probably nothing more than a sleeve to get from outside to inside. If the conduit comes in inside of another stud bay the panel could get moved over there and bottom fed with a conduit coming in the bottom.

There is an exception for installs prior to the '08 code that allows three wire feeders provided there are no metallic pathways between the buildings, but to be honest, I don't know if changing the panel would nullify the exception, thus requiring an equipment ground conductor. That require a call to the AHJ. I've never changed a panel that was installed with a three wire feeder so I've never had to question it. If it's ok, then the neutral will need to be bonded and the two rods planted. This plan of action would be dependent on the URD being dual rated for indoor use and there's a good chance it isn't. The best thing to do is to replace the entire feeder with a four conductor and be done witpanel,

EDIT: I just realized that the conduit comes up outside the wall but inside the garage. It might be easier to surface mount the panel, bottom fed, and take the guts out of the old panel and turn it into a junction box. I do that all the time and just screw the door shut.

 

[wyliesdiesels]

The feed wires are in a clamp. If you have conduit, why doesn't the conduit extend to this panel? Are the wires loose behind the wall?

yup then theres this.... loose conductors need to be in conduit

 

[wyliesdiesels]

The 3" conduit comes up through the concrete in the corner of the garage below the subpanel and elbows into the wall.... I'm assuming the wires are bare inside the wall from this elbow to the subpanel.

and that is not code compliant either

 

[Innovate1]

I think the new panel needs to have a main breaker not just bus lugs - not sure what you were planning to use there. If the conduit extends out past the foundation and ends there you can run the wire to the ground rods thought it. Then ditch between buildings for wire run. That's assuming the conduit isn't continuous which is probably the case. How long of run between buildings? More pictures would help. What's the house end situation look like? Probably similar issues there.

 

[TylerRNEMT]

Yeah no question the "conduit" used was Plumbing grade PVC.... Still have no idea if it runs continuously from the Source panel at the house to the garage.... Obviously I have a considerable amount of code violations here..... It's very frustrating to me that they took the time to run wire, use conduit etc. but not use the correct stuff and do it correctly.... I can't imagine it would have made things any easier to do it this way nor would it have saved much money to do it this way rather than doing it correctly. The garage was built in 2002 so it would have been pre-2008 so I understand using the 3 wire instead of 4 but why not bond at the subpanel.... Why not use electrical conduit instead of PVC and why run it up through the slab and not in the wall.... So many questions.

It is about a 70ft stretch from the main panel to the garage panel.... I am estimating loosely I will need 100ft taking into consideration the risers.

Unfortunately it won't be easy to retrench this area.... As you can see in the pics there is now a deck, thick gravel drive, and concrete slab between deck and garage all now on top of what appears to be the path from Main Panel at the house to the sub panel in the garage which is located just to the right inside the man door seen in the pics below.

The 100 amp subpanel I bought to do the exchange does have a main breaker.






-Tyler

 

[Innovate1]

I am guessing the riser near the meter at the house with a 45 bend near the ground is the one to the garage? If so the bend doesn't go toward the garage... I would take a shovel and dig down to find the end of the PVC. All indications are it doesn't go the whole way, especially since it doesn't even curve in the right direction. Another thing you could try to do is disconnect the wire at both ends and pull it if it moves then maybe it goes all the way but very unlikely it does. If retrenching you may need to run power into the garage at some other point. I didn't see the slab you mention in the photos. If the pipe is in a usable position in the garage and runs to outside the foundation I would consider cutting it off just above the slab and installing PVC conduit fittings - a 45 into the wall, etc. The sizes of PVC plumbing and electrical conduit are exactly the same. You may have some difficulty getting the new wire through the 45 fittings they probably used. Given all the trouble to figure out what is where it would be easier to just run a new conduit up the side of the garage and into the wall - that's what is often done and looks like that would avoid the concrete pad too.

 

[wyliesdiesels]

I think the new panel needs to have a main breaker not just bus lugs - not sure what you were planning to use there. If the conduit extends out past the foundation and ends there you can run the wire to the ground rods thought it. Then ditch between buildings for wire run. That's assuming the conduit isn't continuous which is probably the case. How long of run between buildings? More pictures would help. What's the house end situation look like? Probably similar issues there.

If he will have more than 6 breaker handles then he will need a main disconnect

 

[Innovate1]

If he will have more than 6 breaker handles then he will need a main disconnect

He already has 7 and is adding more. If he makes that a subpanel he might end up with no more than 6 but main breaker covers everything.

 

[wyliesdiesels]

Well seeing the mess they made with that white plumbing PVC, i would just run new conduit.

No telling what other hack jobs they did

 

[sparky 1971]

I doubt the pvc is anything more than a sleeve at the ends. To add to the mess, the panel needs a clear space 30" wide and 3' deep in front of it. The panel or the bench need to move.

 

[89MustangGX]

I had a somewhat similar situation recently - previously installed/inspected 3-wire 100-amp 8-slot subpanel that I wanted to change. I installed a 100-amp 20-slot panel in it's place, as a direct replacement. I believe that was the key - that is was a direct replacement, not an "upgrade" - I don't remember the exact wording but that is how I explained the work I did to the inspector. Inspector passed it. I did need to make sure it was installed to the previous code, which meant bonded neutral/ground.

The question that still remains to me is about the ground to the panel. Without that it doesn't even meet previous code. I suppose you will have to make a decision over it being easier/better to add ground rods and maintain the previous code or run a ground back to the main panel and meet current code. For me, running back to the main panel would have meant tearing up pavement and concrete and a pretty decent trench, and I wasn't interested in that.

 

[Crazyjake8493]

I doubt the pvc is anything more than a sleeve at the ends. To add to the mess, the panel needs a clear space 30" wide and 3' deep in front of it. The panel or the bench need to move.

Agreed. Judging by all the other hack work, I bet the "conduit" was just some PVC they had laying around just to make it look pretty above-ground at the time.

 

[Norcal]

Agreed. Judging by all the other hack work, I bet the "conduit" was just some PVC they had laying around just to make it look pretty above-ground at the time.

"Pretty" is one of the last words I would use to describe that abortion.

 

[beemerphile]

 

[AntonLargiader]

Without trying to defend the existing installation in any way, let me say that if you simply need a space for your mini-split breaker that you take a good look at your existing 120s and see if they all really need separate breakers. If you have several that are dedicated to outlets that don't see any real loads, you may be able to combine and make some space.

My shop has what I felt were plenty of receptacles but in reality are nowhere near enough that I don't have to keep plugging and unplugging small loads like parts washer, blast cabinet, valve grinder, valve seat grinder, stone dresser, lathe, phone charger, drill press, grinding wheel, hand drill, ultrasonic cleaner... the list goes on. Most of these (and anything with a motor) are impossible to use simultaneously with another and some loads are tiny. For instance you may only need one for lights and two for receps.

Yes, it's sidestepping the update that you want to do, it's extending the use of a poorly built system, and it's tempting to use the mini-split as the impetus for this change. But updating the feeder is a project that stands on its own merits and maybe doesn't need to hold your mini-split hostage.

 

[Innovate1]

Without trying to defend the existing installation in any way, let me say that if you simply need a space for your mini-split breaker that you take a good look at your existing 120s and see if they all really need separate breakers. If you have several that are dedicated to outlets that don't see any real loads, you may be able to combine and make some space.

My shop has what I felt were plenty of receptacles but in reality are nowhere near enough that I don't have to keep plugging and unplugging small loads like parts washer, blast cabinet, valve grinder, valve seat grinder, stone dresser, lathe, phone charger, drill press, grinding wheel, hand drill, ultrasonic cleaner... the list goes on. Most of these (and anything with a motor) are impossible to use simultaneously with another and some loads are tiny. For instance you may only need one for lights and two for receps.

Yes, it's sidestepping the update that you want to do, it's extending the use of a poorly built system, and it's tempting to use the mini-split as the impetus for this change. But updating the feeder is a project that stands on its own merits and maybe doesn't need to hold your mini-split hostage.

That would be really sloppy and not safe. At least put the wire in conduit where exposed in the walls, add ground rods and bond the panel. As it is it appears to have no connection for the grounds - they are just tied together and to the box. Any small leakage current and all the grounds are going to be hot.

 

[AntonLargiader]

Yes, but those problems are all there whether or not he adds another circuit. If it's unsafe to use then he should stop using it at all. My only point is that adding the mini-split is a separate project. If he replaces two of the singles with a double for a mini-split then he's at six handles and is just an EGC away from being correct, right? And has a system that was perfectly acceptable at some point in the past? If he doesn't want to retrench until springtime for whatever reason, I don't see why he can't have heat in the meantime.

 

[wyliesdiesels]

Yes, but those problems are all there whether or not he adds another circuit. If it's unsafe to use then he should stop using it at all. My only point is that adding the mini-split is a separate project. If he replaces two of the singles with a double for a mini-split then he's at six handles and is just an EGC away from being correct, right? And has a system that was perfectly acceptable at some point in the past? If he doesn't want to retrench until springtime for whatever reason, I don't see why he can't have heat in the meantime.

neutral isnt bonded. thats an issue that needs to be addressed regardless of all the rest of this.

 

[Innovate1]

neutral isnt bonded. thats an issue that needs to be addressed regardless of all the rest of this.

Yep. That's the biggest safety issue as I see it and easily addressed. The system never, ever was "perfectly acceptable".

 

[wyliesdiesels]

IF there are parallel metallic pathways between the buildings then he cant bond the neutral and will need a 4th wire