Lifting Neutral/Ground Bond on an old ITE panel

[longcreekridge]

Hello. Main question is asked in my thread title. Here's some additional context (sorry to be long winded):

I look after an old farmhouse collectively owned by my wife's family. The kind where the (200A) electrical service is on a power pole outside, with a panel and a main breaker/disconnect that feeds another (sub) panel inside. Evidently the original install dates from a time, or was installed in an area (rural Central VA), when full size grounds were not always run. The external panel has neutral and ground bonded, as you would expect. The internal house panel is only fed by two hots and a neutral. The internal panel (an old ITE) also has its neutral and grounds bonded (see pic). I recently learned that this is incorrect, at least according to current code, and actually creates an unsafe situation. The situation is complexified and compounded by the fact that that I recently built a workshop near the house that is solar powered, and I am 99% complete with the process of tying that solar power into the house for both backup and load sharing (90A breaker on shop panel > 2-2-2-4 mobile home feeder > 100 amp external disconnect > Reliance A510C Transfer Switch > Internal Panel).

After explaining all this on a solar power forum, I was informed that I needed to rectify the situation by:
A) Running a full size ground from external panel to house panel
B) Lifting the ground/neutral bond in the house panel.

I've done A but need some help with B. I experimented a bit yesterday (with power off) and thought I had figured out where the bonding occurs. In the second pic, I've circled two areas. The top one is where I first thought the bonding occurs, but no dice. You can't see it, but the bottom circle highlights a screw that seems to tie the grounding bar into the built in panel ground that runs across to a symmetrical prong on the other side. However, even with all these screws backed out I was still getting continuity between the neutral and ground bars. What am I missing or getting wrong? Thank you kindly to anyone who can help.

 

[mm08822]

Let's back up on a few points.

• Grounds were never run as full size except for #14, 12 and #10 branch circuits.
• A 200a feeder would require a #6 copper ground wire back to its source.
• Neutrals can be reduced in size up to 70% (roughly) if load calcs permit.

Your sub-panel is fed with what could be galvanized conduit. If the conduit is complete between the pole and sub-panel, that would be the equipment equipment grounding conductor between the 2 locations.

There is also an aluminum conductor (#4?) on the left side of the panel exiting the bottom of the panel. It could be bonding the water system and possibly connecting to a ground rod/electrode.

How did you run this additional ground wire and where connected at each end?

I can't be certain from the pics, but both pairs of blocks may be simply stacked neutral bars. If so, you will need to add a ground bar (or 2 for convenience) attached to the back of the enclosure and move all ground wires to them. Also move the #4 Al.

There would be a lot of wires to lift in order to test for isolation between neutral and grounded enclosure. This would include the bonding screw/jumper at the pole. Until you add the grd bars, I wouldn't bother to measure again.

Possibly, the screw you circled in red is a bonding screw.

Post some pics of the connection to the garage including the solar tie-in.

 

[longcreekridge]

Thank you so much for the reply, mm08822. I think I used "full size" incorrectly. I guess I really meant "sufficient". I excavated just enough of the original feeder run to determine that the only galvanized conduit is the run under the house. The rest of the service feed is under ground, with no conduit. I have not found where the aluminum ground conductor you mentioned terminates, but it does not run back to the pole and I believe it ties into a ground rod.

The new ground wire that I ran is #4 USE-2 aluminum, and it was run in a short branch trench from the pole to the longer trench used for the new solar feeder. I understand that I really should have run a new 4-wire service feeder to the house but chose this route because: A) I was already digging the trench for the solar run, B) The original service feed runs through a really dicey area of the yard, with lots of obstructions, and C) A new run would have upped my costs considerably. Really hope that's sufficient as I asked and was told it was, and I already backfilled the trench :-(.

The new ground is not presently terminated on either end until I understand how to do so properly. The lug in the pole box that presently bonds neutral to ground is badly corroded and probably needs replacing, but I figured I would terminate it there, or possibly (less optimal) use a split bolt splice.

I have acquired one new ground bar (not pictured) and affixed it inside the house panel. Suppose I probably need a second to accommodate all those circuits, but if I am understanding you correctly, to correctly lift neutral/ground bond, I would move all the house panel grounds to the new ground bar(s) and not need to do anything else inside the house panel with regards to lifting the bond?

Edit: Anything else besides also connection the new ground wire to one (or both?) of those ground bars. What are those lugs called that allow for for larger connections on ground bars?

 

[mm08822]

Take a pic from the left side of the panel to show the side view of the neutral block stack.
Neutral wires must each have a dedicated hole to terminate into. No doubling up.
Ground wires can be doubled according the mfr's instructions. (Read them!)

The garage feeder comes from the pole panel and not the house panel?

Where will the transfer switch be located?

 

[longcreekridge]

Unfortunately, I am not at the farmhouse right now. I tend to do my research at my main home, where there is much better internet. Will take pics in a few days, and hopefully can get feedback later, but I'm pretty certain there are no doubled up neutral connections in the house panel (or doubled grounds for that matter).

The garage/shop, where the solar equipment lives, is not on-grid or fed by the power company at all. It is entirely solar powered. I dug a trench from the shop to the house, where I ran the 2-2-2-4 mobile home feeder, as well as the new ground. The Reliance transfer switch is installed right next to the house panel. Maybe this diagram will help visualize the whole system.

EDIT: I see now that a few neutrals and grounds are shared. Not sure why as there are spaces available. I will rectify that.

 

[mm08822]

Is the diagram correct?

What is the purpose of the xfer switch? It should have 2 sources and 1 load for output.

 

[longcreekridge]

Yes, it's correct but doesn't really detail the transfer switch wiring. The Reliance transfer switches (my specific model is linked) are a little more complicated than the simple on-off-on knife switches. They're primarily designed for generator hookups, but solar folk have been using them to get a little more flexibility with balancing loads. So in this case, the 2 sources are the grid (200A pole > house panel feed) and the solar feed. My model controls 10 chosen circuits (well, 8 really, because two are double breakers). You can switch between grid and solar as needs, battery levels, sunlight dictate. That is partly why getting the neutral/ground bond correct at the pole is important, so all grounds terminate there.

 

[mm08822]

Ok, I see the transfer panel details now.

You would get more flexibility if you put in a 200A xfer switch and fed the entire sub-panel from it. Needs change, loads change.

 

[Norcal]

Not sure anyone has answered your question about the bonding screw, it is the one you had circled.

 

[longcreekridge]

Not sure anyone has answered your question about the bonding screw, it is the one you had circled.

Thank you. The top one? So, I would need to move all the grounds to the new ground bars and back out this screw to complete the unbonding, correct?

 

[longcreekridge]

Ok, I see the transfer panel details now.

You would get more flexibility if you put in a 200A xfer switch and fed the entire sub-panel from it. Needs change, loads change

I can only produce about 50A or 12000w on the solar end. That could change of course, but I don't see myself spending money on additional capacity anytime soon. So since the plan was never to power everything in the house, I didn't really want to lock myself into an either/or situation. This setup allows me to blend grid and solar simultaneously and adjust at will (e.g. if there's isn't enough capacity on any given day to run the hot water heater, I can flip the breaker/switch and run just that on grid while still powering the other things with solar). Unless I'm misunderstanding something, that isn't possible with traditional transfer switches.

 

[Norcal]

Thank you. The top one? So, I would need to move all the grounds to the new ground bars and back out this screw to complete the unbonding, correct?

The screw needs to be removed completely.

 

[mm08822]

I can only produce about 50A or 12000w on the solar end. That could change of course, but I don't see myself spending money on additional capacity anytime soon. So since the plan was never to power everything in the house, I didn't really want to lock myself into an either/or situation. This setup allows me to blend grid and solar simultaneously and adjust at will (e.g. if there's isn't enough capacity on any given day to run the hot water heater, I can flip the breaker/switch and run just that on grid while still powering the other things with solar). Unless I'm misunderstanding something, that isn't possible with traditional transfer switches.

You will become a master at monitoring/forecasting generation, storage level and planned 24 hr consumption in order maximize utilization of your "free" solar.
Once the batts are topped off, you will need a connected and energized load to consume ongoing generation otherwise that energy isnt harvested.
Your usage in the shop could be the priority as it is run on batts only. Lighting could be minimal, but ac, air compressor, welder usage would **** down the batts in no time.
Patchy clouds/rain could make the best of plans crash. Also unplanned garage usage/extended usage could be impeded.

Seems like a fun challenge but may become a fulltime job. Maybe future automation could simplify once you have some run time.

 

[larry4406]

Kick on resistance heat when there is excess solar production to heat large insulated tanked water for later use in space heating?

Yes scope expansion.

 

[Bert_]

Leave the panel bond and the 3 wire feed alone. It is legal and safe as installed. This is not a new install and code is not retroactive.

If you run a feeder for the house panel to the shed it should be 4 wire.

Is a 4 wire feeder better? Yes

Is a 3 wire feeder unsafe? No, it was a code compliment install for decades. The line side of every service in the whole country is a 3 wire feed.

 

[mm08822]

Kick on resistance heat when there is excess solar production to heat large insulated tanked water for later use in space heating?

Yes scope expansion.

Could be. Depends on weather, time of year, house occupied. This is where the challenge comes in to get the benefit vs. Just burning it off.

 

[mm08822]

Leave the panel bond and the 3 wire feed alone. It is legal and safe as installed. This is not a new install and code is not retroactive.

If you run a feeder for the house panel to the shed it should be 4 wire.

Is a 4 wire feeder better? Yes

Is a 3 wire feeder unsafe? No, it was a code compliment install for decades. The line side of every service in the whole country is a 3 wire feed.

OP is almost done with the changeover to 4 wire feeder. At this point, just finish it. With all the new hardware installed, it better to ensure no unintended paths are created. (Not worth the time to think of multiple scenarios where it may/may not occur.)

Line side wiring on a service doesn't have near the opportunity for random changes to occur as compared to those made by unsuspecting/unknowing homeowners/contractors at a residence.

 

[wyliesdiesels]

Leave the panel bond and the 3 wire feed alone. It is legal and safe as installed. This is not a new install and code is not retroactive.

If you run a feeder for the house panel to the shed it should be 4 wire.

Is a 4 wire feeder better? Yes

Is a 3 wire feeder unsafe? No, it was a code compliment install for decades. The line side of every service in the whole country is a 3 wire feed.

flawed comparison..... youre not gonna have the potential for shock on the line of the service meter.... on the load side it is possible with modifications by people who dont know what theyre doing.... lets say a metal water line gas line or comms is added between these buildings by an unsuspecting person. this not only violates code but sets up a potential for shock

OP already ran the ground wire but youre advocating he just waste the money and time he already spent to run the ground wire and abandoned it.... not very good advice IMPO

 

[longcreekridge]

You will become a master at monitoring/forecasting generation, storage level and planned 24 hr consumption in order maximize utilization of your "free" solar.
Once the batts are topped off, you will need a connected and energized load to consume ongoing generation otherwise that energy isnt harvested.
Your usage in the shop could be the priority as it is run on batts only. Lighting could be minimal, but ac, air compressor, welder usage would **** down the batts in no time.
Patchy clouds/rain could make the best of plans crash. Also unplanned garage usage/extended usage could be impeded.

Seems like a fun challenge but may become a fulltime job. Maybe future automation could simplify once you have some run time.

All good points, but I'm not going to get too hung up on unused power. There's an app called Solar Assistant that helps with the monitoring and crunching numbers. The shop is almost entirely woodworking oriented, so I don't weld much, only have a pancake compressor, and don't have AC (yet). I can run my saws, dust collector, sanders, planer, routers, etc. off and on all day and not drain the batteries much. I have a 240v heavy duty timer to put on the hot water heater, and will dump afternoon sun into that. Lots of 20v and 40v tools, and can time the battery charges for those as well. Also have an EV hookup for visitors and when the wife decides to get one ;-). Goals were to keep e bills down in the house (who pays those bills is complicated with a family owned place), power the shop, and provide some outage backup w/o mucking around with interconnect agreements or net metering. Those goals will be met so I'm happy with the setup.

 

[AntonLargiader]

Sounds very much like the post-WW2 farmhouse in rural central VA where I grew up. I'm still in central VA, but not in that house any more. I remember grounded receps with the ground tied to the neutral, ground pins broken off so they could be plugged in, and the ground adapters that bonded to the cover screw. Ahh, the good old days just when 2-prong was being confused by 3-prong. We lived through it.

If you're not far from Charlottesville I'd be happy to look it over with you.

 

[longcreekridge]

Sounds very much like the post-WW2 farmhouse in rural central VA where I grew up. I'm still in central VA, but not in that house any more. I remember grounded receps with the ground tied to the neutral, ground pins broken off so they could be plugged in, and the ground adapters that bonded to the cover screw. Ahh, the good old days just when 2-prong was being confused by 3-prong. We lived through it.

If you're not far from Charlottesville I'd be happy to look it over with you.

The house was built in 1913 (a bit south of Appommattox), but it's been through a few phases, and I'm not entirely certain when it got wired for electricity. All the older outlets lack a ground, which I hope to update soon. Thank you kindly for the offer. I completed the install last week and everything has been running fine so far, so I think I'm good.

 

[AntonLargiader]

That house (1942 comes to mind) was all 2-prong and because 3-prong cords were new on the market in the '70s people were switching outlets to 3-prong tying ground to neutral just so they could get on with things.

The house I'm in now - 1930 - still had a lot of knob & tube when we moved in. It's all 3-wire now, though.

 

[mm08822]

Houses built in the 50's with BX easily converted to 3-wire recepts.

IF your installer performed proper BX installation, grounding through the armor was very good.

 

[AntonLargiader]

I don't remember if it was BX or not. This was farm country (probably 15~20 minutes from the OP) in the '70s and I bet a lot of people were not using electricians.