Using Ground as a Neutral at a Distant Sub Panel

[MrSurly]

I still think that using a 120v pump would be the simplest and quickest way to make the pump setup safe. Eliminates the uninsulated neutral AND let’s the bare conductor be the egc as it should be.


Sent from my iPhone using Tapatalk

 

[wyliesdiesels]

I still think that using a 120v pump would be the simplest and quickest way to make the pump setup safe. Eliminates the uninsulated neutral AND let’s the bare conductor be the egc as it should be.


Sent from my iPhone using Tapatalk

The way i see it, its probably cheaper to replace the feeder than it is to get a new motor.

 

[Bert_]

Okay, now do I have it correct ?

What you have drawn shows the primary side wired 480. You need to connect H1 and H3 then H2 and H4 for 240v input.

 

[Jimt1000]

OK, I've looked at the replies in some detail and I'm going to attempt to reply to wyliesdiesels' comments particularly and see if I can articulate correctly a plan of action. I've placed wyliesdiesels' comments below in red with my follow up commentary/questions below.

In regards to the Main Service Panel feed to the Old Shop Sub Panel:

It is actually INCORRECT. You have a 4-wire feeder here but the neutral bus is bonded to the can. This is a no-no!!!

To clarify, if you look closely at the schematic, you'll notice the two Neutral bus bars are bonded together, but isolated from the ground bus bar which is actually bonded to the panel. So, the neutral is NOT bonded to the can. Hence, I'm thinking to this point, this is all correct and to code (current and past).

In regards to the Old Shop Sub Panel feed to the Apartment Sub Panel:

Ok this is where details are important. Since the old shop subpanel and old apartment subpanel are in different structures, the 3-wire feeder is up to code if wired PRE-2008 (not 2005) as long as there are no parallel metallic pathways such as water and gas lines, communication lines, etc.

The part you said about grounding system and ground rods has nothing to do with the code allowing 3-wire feeder to detached. the EGC in this case is ran over the neutral and the grounding electrodes are required regardless. Keep in mind, the grounding electrodes do not establish an EGC, they are for shunting lightning.

To clarify, there are NO metallic pathways to the Apartment structure. In fact, all sub panels in the separate structures have no metallic pathways between them. I understand that it was to code PRE-2008 as a three wire feed and I further understand that the grounding electrodes are for shunting lightning.

Question: To be clear, using PRE-2008 code criteria, the Apartment Sub Panel which has a 3-wire feed is OK to the old criteria (considering no metallic pathways exist between structures) as long as I install a grounding electrode for shunting lightning?

In regards to the Old Apartment Sub Panel feed to the Pump House:

This is definitely not to code and never was. The bare conductor CANNOT be used as a neutral. This creates a shock potential and needs to be corrected immediately.

I acknowledge, understand, and appreciate the comments about the bare copper wire being incorrectly used as a neutral. I also understand the following comments about the dangers of not rectifying this condition. Frankly, my discovery of the bare copper wire being used as a neutral was the root cause of my beginning this thread in the first place.
And I feel the only really good solution is to run a new 4 wire feed to the pump house from the Apartment. This way, I could re-wire a proper sub panel in the pump house using dedicated, separate, ground and neutral conductors.

So, in summary, given the clarification above about the Old Shop sub panel (i.e. the neutral bus is not bonded to the ground and can there), I'm considering the following actions:
1) Adding a grounding electrode at the Apartment for shunting lightning and bringing that sub panel to PRE-2008 code compliance; and,
2) Replacing the feed from the Apartment to the Pump House with new 4-wire feed which would then allow me to re-wire the sub panel in the pump house considering the separated ground and neutral at that location. I'll also take this opportunity to properly install the 120V outlet with a lower circuit breaker inline.

Does the above statement of planned actions make sense and seem prudent given my conditions?

Your insight and help is, as always, most appreciated.

Regards, Jimt1000

 

[mike93lx]

Any time you do ground rods, install two, at least 6ft apart. That goes for the apartment and pump house

One is only OK if you can prove resistance, which isn't feasible for a homeowner

 

[Bert_]

While not common bare copper neutral can be allowed for service conductors. Can't recall if it was ever allowed for 3 wire feeders.

 

[theoldwizard1]

I acknowledge, understand, and appreciate the comments about the bare copper wire being incorrectly used as a neutral. I also understand the following comments about the dangers of not rectifying this condition. Frankly, my discovery of the bare copper wire being used as a neutral was the root cause of my beginning this thread in the first place.
And I feel the only really good solution is to run a new 4 wire feed to the pump house from the Apartment. This way, I could re-wire a proper sub panel in the pump house using dedicated, separate, ground and neutral conductors.

This is likely the BEST solution for the pump house, but not the only one !

It depends on the cost of replacing the wire feeding the pump house.

A new breaker box in the pump house and a transformer (creating a "derived system" as wylie called it) is a good valid solution and could be more cost effective.

 

[theoldwizard1]

To clarify, if you look closely at the schematic, you'll notice the two Neutral bus bars are bonded together, but isolated from the ground bus bar which is actually bonded to the panel. So, the neutral is NOT bonded to the can. Hence, I'm thinking to this point, this is all correct and to code (current and past).

IANAE !

I think the issue here is the use of the word "bonding". If I understand the electrical terminology correctly, "bonding" is only used when connecting a neutral bus to a ground bus. Not the case in the Old Shop Sub Panel.

A more clear (for outsiders) pictorial diagram would NOT EVEN SHOW THE SECOND NEUTRAL BUS BAR. Drawing it in does not add "value" to the diagram but does add confusion when you label the connection between the two as a Bonding Strap.

Revised diagram showing only one neutral in the Old Shop Sub Panel.



What would be the cost of installing 4 wire cable from the Old Shop Sub Panel to the Old Apartment Sub Panel ? That (and 4 wire cable to a new sub panel in the pump house) would make the system code compliant the

 

[Terry D]

Bonding is anytime you connect anything metallic to ground potential. When you bond a panel, you are connecting that metal enclosure to ground potential. Bonding is different than grounding. When you bond your neutrals, you are bringing them to the same ground potential

Sent from my SM-G960U using The Garage Journal mobile app

 

[Jimt1000]

Thanks theoldwizard1 for the clarification on the schematic. In regards to getting a new 4-wire installation from the Old Shop Sub Panel to the Old Apartment Sub Panel, that would be very, very, difficult. It could be done, but very difficult. I would likely end up leaving the existing 3-wire feed to the Old Apartment (two hots and the neutral) and then running a dedicated ground wire from the Old Shop to the Old Apartment. Then, at the Old Apartment, I could bring that sub panel up to current code. However, It would be easier for me to leave that sub panel at the Old Apartment alone with the 3-wire feed from the Old Shop and then simply install a proper grounding electrode at the Apartment; hence, making it code compliant PRE-2008, if I'm understanding things correctly. Installing the grounding electrode at the Old Apartment sub panel would be much, much, easier than trying to run a ground wire out to the Old Apartment from the Old Shop and immensely easier than trying to run a new 4-wire feed out to the Old Apartment.

Running a new 4 wire feed from the Old Apartment to the Pump House can be done relatively easily... Just some digging without any obstructions in the way and we have plenty of equipment for digging on the Ranch...

Thanks for the help, Jimt1000

 

[wyliesdiesels]

Okay, now do I have it correct ?

no still not correct. the high side shows 480v 3 phase. It needs to be 240v single phase with one coil not 480v 3 phase open delta with 2 coils. There should only be A and B

what are you using to draw these transformer diagrams?

OK, I've looked at the replies in some detail and I'm going to attempt to reply to wyliesdiesels' comments particularly and see if I can articulate correctly a plan of action. I've placed wyliesdiesels' comments below in red with my follow up commentary/questions below.

In regards to the Main Service Panel feed to the Old Shop Sub Panel:

To clarify, if you look closely at the schematic, you'll notice the two Neutral bus bars are bonded together, but isolated from the ground bus bar which is actually bonded to the panel. So, the neutral is NOT bonded to the can. Hence, I'm thinking to this point, this is all correct and to code (current and past).

In regards to the Old Shop Sub Panel feed to the Apartment Sub Panel:


To clarify, there are NO metallic pathways to the Apartment structure. In fact, all sub panels in the separate structures have no metallic pathways between them. I understand that it was to code PRE-2008 as a three wire feed and I further understand that the grounding electrodes are for shunting lightning.

Question: To be clear, using PRE-2008 code criteria, the Apartment Sub Panel which has a 3-wire feed is OK to the old criteria (considering no metallic pathways exist between structures) as long as I install a grounding electrode for shunting lightning?

In regards to the Old Apartment Sub Panel feed to the Pump House:


I acknowledge, understand, and appreciate the comments about the bare copper wire being incorrectly used as a neutral. I also understand the following comments about the dangers of not rectifying this condition. Frankly, my discovery of the bare copper wire being used as a neutral was the root cause of my beginning this thread in the first place.
And I feel the only really good solution is to run a new 4 wire feed to the pump house from the Apartment. This way, I could re-wire a proper sub panel in the pump house using dedicated, separate, ground and neutral conductors.

So, in summary, given the clarification above about the Old Shop sub panel (i.e. the neutral bus is not bonded to the ground and can there), I'm considering the following actions:
1) Adding a grounding electrode at the Apartment for shunting lightning and bringing that sub panel to PRE-2008 code compliance; and,
2) Replacing the feed from the Apartment to the Pump House with new 4-wire feed which would then allow me to re-wire the sub panel in the pump house considering the separated ground and neutral at that location. I'll also take this opportunity to properly install the 120V outlet with a lower circuit breaker inline.

Does the above statement of planned actions make sense and seem prudent given my conditions?

Your insight and help is, as always, most appreciated.

Regards, Jimt1000

ok disregard my comment about the 4-wire panel being incorrect. I misread your diagram

So you need to add 2 ground rods at each panel since theyre all in detached structures.

run 4-wire feeder to pump house, put 2 ground rods in and change breaker for 120v outlet and you will be good

 

[theoldwizard1]

what are you using to draw these transformer diagrams?

I stole the original off of the Acme Transformer web page and have been modifying it.

Clearly I grabbed the wrong drawing to begin with !

 

[theoldwizard1]

Running a new 4 wire feed from the Old Apartment to the Pump House can be done relatively easily... Just some digging without any obstructions in the way and we have plenty of equipment for digging on the Ranch...

Go for it !

Now you said it was likely never going to be inspected and that is good, because you need a 4 wire feed to the Old Apartment Sub Panel to be compliant. If that feed is currently 3 separate wires in a conduit then you can add the fourth (green) wire. It is it some kind of factory made cable, it would have to be replaced.

 

[Jimt1000]

OK gents... I have a plan and will execute accordingly. I'll be adding the grounding electrodes at the sub panels and I'll be providing new 4 wire service to the pump house and putting in a separate breaker for the 120V outlet.

Thanks to all for the comments. I really appreciate it!

Jimt1000

 

[mike93lx]

Make sure you don’t just string a piece of thhn between the main and apartment (that would require conduit) . Once you come up with specifics, please post up with details, before you buy supplies.

 

[Jimt1000]

Thanks... For the new 4 wire feed to the Pump House from the Old Apartment, I'm planning on using THHN in PVC conduit, 12AWG. The specs for the pump motor state the max. draw is 7 amps at 230V. The distance is exactly 101 feet. So that will give me between a 1% to 2% voltage drop which should be just fine for the motor. The existing 3 wire feed (with the bare copper conductor used now as a neutral) is also 12 gauge wire and since the 60's, there's been a pump running off that feed without problems. I've never had problems with the pump motors; the pumps I've had to replace (3/4HP) have all had impeller problems due to the hard water with the solids in the well water (i.e. the plastic impeller goes bad and it's easier to simply replace the pump than mess with a new impeller and seal kit). So, the impeller is going to give me cavitation problems long before the motor goes out. Thanks for the support and help. Jimt1000

 

[theoldwizard1]

Thanks... For the new 4 wire feed to the Pump House from the Old Apartment, I'm planning on using THHN in PVC conduit, 12AWG.

Then you need to down grade the breaker in the Old Apartment to 20A. For 100' you would get about a 7% voltage drop. Starting current is multiple times that of running current. Don't cheap out USE 10AWG !!

If am not sure what the code says about wire color that size (ground must be green or bare) but the difference in cost between 500' of 12AWG and 10AWG is about $40. Buy some red and white tape to mark each end. You CAN save a couple of buck by using solid wire but it is much more difficult to pull especially if you have multiple bends in the conduit.

Check pricing at Wire and Cable Your Way


Picking a nit : Any wire buried in a conduit must be THWN. The good thing is almost all THHN is also rated THWN.

 

[mike93lx]

Is the pump in the house or below grade? If below, consider the length of that wire as well.

That said, my well is wired with 12 as well and is 125' in the ground, plus about 100' from the panel to the well head. Also draws 7a running

My comment about thhn wasn't knocking that wire just making sure you knew that it has to be in conduit everywhere. For underground use, make sure you get wire that is dual rated thhn and thwn

 

[Jimt1000]

The pump is at grade so the 101 ft. stated above is an accurate distance considering all bends, etc. My well is actually at another location and this pump serves an above ground water tank. Thanks and regards, Jimt1000

 

[mike93lx]

The pump is at grade so the 101 ft. stated above is an accurate distance considering all bends, etc. My well is actually at another location and this pump serves an above ground water tank. Thanks and regards, Jimt1000

12 is fine. 10 won't hurt anything, but that isn't how I would spend my money

 

[Jimt1000]

Yep... Thanks... Time to build this and solve the problem (potential problem; excuse the pun)...