Does a meter replacement require main wire upgrade?

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I have an issue where I recently needed to change a meter on the outside of the house to allow for a pool installation. The reason for this was because the main panel in the house is on the second story with no attic access to allow for new circuits. It is placed on an interior wall that is directly above the ceiling in a dining room, so to run any wires would involve renovation (sheetrock cuts, painting, etc.)-a proposition that the homeowner refused. My solution was to change the meter for a meter/sub panel combination. The catch is that the meter can on the outside was a meter only with no primary disconnect or main breaker. The inspector initially approved the change, but then later (after the work was done) said that the feed wires to the main panel upstairs (which is now effectively a sub-panel) have to be upgraded to a 4-wire bundle instead of the existing 3-wire bundle. I didn't change the amperage coming into the house, and I didn't change anything existing other than the meter to allow for additional outside circuits. If anything, I feel that the service is safer because it provides protection for the 30+ feet of main feed wire that runs through the walls and attics of the house. Be that as it may, I know that the code requires 4-wire conductors for new installations. But is there not a "grandfather" rule for existing installations?
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Yes , The neutral and Grounding conductor must be separate at a sub panel. The grounding conductor cannot carry current except in a Fault condition. That is why you must now run a new wire to the original panel now used as a sub.
No grandfather rule would apply as you have modified the system. You made a main panel into a sub. If you left it alone you would be ok.
 

growler

Senior Member
Location
Atlanta,GA
The inspector initially approved the change, but then later (after the work was done) said that the feed wires to the main panel upstairs (which is now effectively a sub-panel) have to be upgraded to a 4-wire bundle instead of the existing 3-wire bundle.

You will also have to seperate the neutrals and grounds of branch circuits within this sub panel ( install a ground bar).

When you install a new main you will have to bring the system ground up to code.

The fun just never ends.
 

ceb58

Senior Member
Location
Raeford, NC
to run any wires would involve renovation (sheetrock cuts, painting, etc.)-a proposition that the homeowner refused.

Some times the HO just has to suck it up. They want a pool, then they have to do what needs to be done or you walk away.

The inspector initially approved the change, but then later (after the work was done) said that the feed wires to the main panel upstairs (which is now effectively a sub-panel) have to be upgraded to a 4-wire bundle instead of the existing 3-wire bundle.

The inspector should have known it was wrong from the start.

If anything, I feel that the service is safer because it provides protection for the 30+ feet of main feed wire that runs through the walls and attics of the house

In essence you have made it more dangerous than it was. In the event of a ground fault there may not be enough fault current to trip the new main but it would now energize the metal non current carrying parts.
 
"In essence you have made it more dangerous than it was. In the event of a ground fault there may not be enough fault current to trip the new main but it would now energize the metal non current carrying parts."

But would it not have been this way regardless of if there was a breaker outside or not? I see your point regarding the fault current not being enough to trip the new breaker I put in. I understand where I was wrong about it being safer in regards to providing overcurrent protection. But by that same point, I don't see how it is any more dangerous. If it were just a meter (as previously existed), any ground fault between it and the panel would do the same thing: energize the metal non-current-carrying parts and provide no protection. By having the new breaker outside, it may not offer over-current protection for the main feeder wire (which overcurrent protection never existed in the first place), but it would offer a safer and faster disconnect means for emergency personnel if needed. The main panel in the house still has it's main breaker, as existing, and the neutrals and grounds in the existing panel still have the exact same path to ground as before, each having the same individual overcurrent protection they've always had.
 

growler

Senior Member
Location
Atlanta,GA
I recently needed to change a meter on the outside of the house to allow for a pool installation. My solution was to change the meter for a meter/sub panel combination. The catch is that the meter can on the outside was a meter only with no primary disconnect or main breaker. The inspector initially approved the change, but then later (after the work was done) said that the feed wires to the main panel upstairs (which is now effectively a sub-panel) have to be upgraded.

The inspector should have known it was wrong from the start.


There is no rough inspection on a meter base change so the first time the inspector would have seen the work would have been on completion.

It's very hard for an inspector to answer questions on work that he hasn't seen unless the right questions are asked. The OP keeps saying that he changed a meter and not that he installed a new main. There is a big differance.

We had some guys that called a local inspection department and asked if it was OK to use #14 NM for residential. The inspectors says sure. They use #14 for everything to include small appliance and bath circuits. They were a little upset because they failed inspection. There were a few other problems like the main panel in a clothes closet that didn't even have working clearance. No exterior disconnect and the panel 40 feet inside the house. Probably the worst looking job I have seen in some time. One more little thing is they were not licensed and dumb enough to let the inspector know it was a homeowner permit.
 
Yes , The neutral and Grounding conductor must be separate at a sub panel. The grounding conductor cannot carry current except in a Fault condition. That is why you must now run a new wire to the original panel now used as a sub.
No grandfather rule would apply as you have modified the system. You made a main panel into a sub. If you left it alone you would be ok.

Again, it has always carried the neutral load from the house. By having the neutrals and grounds tied together there, weather or not it is a sub panel doesn't change the fact that the existing grounding conductor has always carried that load. I'm not trying to be stubborn. I just don't see the functional difference.
 

growler

Senior Member
Location
Atlanta,GA
I didn't change anything existing other than the meter to allow for additional outside circuits. I know that the code requires 4-wire conductors for new installations. But is there not a "grandfather" rule for existing installations?


This is a new installation. You didn't change out a meter base. You removed a meter base and installed a meter/main with provisions for additional circuits ( new main panel ).

You can change out the meter base as a repair without bringing the whole system up to code. what makes you think that you are not doing new work? You have changed the location of the main panel.
 
This is a new installation. You didn't change out a meter base. You removed a meter base and installed a meter/main with provisions for additional circuits ( new main panel ).

You can change out the meter base as a repair without bringing the whole system up to code. what makes you think that you are not doing new work? You have changed the location of the main panel.

I concede all points relating to what the code says and that it needs to be fixed. The following questions I ask not to be stubborn, but I really want to understand what is happening with the system and why it is dangerous. It was never fully addressed while I was in training, and it seems that my understanding is lacking, so I really want to know. If I seem frustrated, it's because I hate doing things just because "it's what the book says" when it seems to fly in the face of common sense. I have seen many conflicting and contradictory things in the code that even my teachers conceded were self defeating. I just want to know how it makes sense. So, bearing in mind that I'm not trying to be snarky--I just really want to understand--here is my new question:

How is it functionally different? Isn't this, on a smaller scale, exactly how the power grid in general is set up? At each residential transformer, power is stepped down to usable voltages and then sent out with only two hots and a grounding conductor. There is no grounded conductor that carries current back to the transformer. My understanding is that a true neutral, not a grounded conductor, only exists in three-phase electrical systems where it carries the imbalanced load between the three different phases. (As I deal only with residential systems, I confess my grasp on three-phase is weak). So, regarding single phase, residential systems: what is the danger of combining the grounded and grounding conductors? And if there is a danger inherent in combining the neutral (grounded) conductor and the grounding conductors in the panels, why not bring 4 wires from the transformers? Why, if all the load is carried on the grounding conductor back to the transformer, is it less safe in my scenario? They are all tied together, regardless of weather in the main panel or any sub-panels. Thus, being of equal electrical potential, any current carried by the neutrals/grounded wires is fed into the grounding conductor. The only physical way that I see electricity can back-feed from the grounding conductor into the grounded conductor is if the grounding conductor from the utility's side is damaged or impeded. Otherwise, it has a clear and unimpeded pathway back to its source regardless of if the neutrals are bonded together with the grounds.

Again--I'm not trying to be snarky. I know we all read things without the speakers intended tone of voice. Please help me see where I am misunderstanding what I think is basic theory.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Using a single combined neutral and EGC to feed the subpanel can have the side effect of allowing real normal neutral current to flow in EGCs in other parts of the site.
This will make it impossible to install ground fault detection upstream of the subpanel among other things.

POCOs are allowed to use, in effect, multiple earth/neutral bonds because it is traditional, it does not usually result in dangerous voltages on grounded metal (but there are cases where it does, and it is then the responsibility of POCO to mitigate that), and POCO installations are subject to a higher level of site specific engineering than standard residential installations.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
How is it functionally different? Isn't this, on a smaller scale, exactly how the power grid in general is set up?
And there are problems with that. It's the reason we have to make equal-potential bonding grids around swimming pools and in dairy farms.
At each residential transformer, power is stepped down to usable voltages and then sent out with only two hots and a grounding conductor. There is no grounded conductor that carries current back to the transformer.
Lets get our terms straight. There is a GROUNDED conductor, physically connected to the earth, at the power company transformer and that same conductor is grounded again at the service. We commonly call that a neutral and it carries current.

Once we move past the service disconnect and move into the world governed by the NEC we want to keep all the current that flows in the house on the insulated conductors and off of any conductive surfaces.

My understanding is that a true neutral, not a grounded conductor, only exists in three-phase electrical systems where it carries the imbalanced load between the three different phases. (As I deal only with residential systems, I confess my grasp on three-phase is weak).
It's the same for single phase systems, the grounded/neutral conductor carries the imbalance from the ungrounded conductors.
So, regarding single phase, residential systems: what is the danger of combining the grounded and grounding conductors? And if there is a danger inherent in combining the neutral (grounded) conductor and the grounding conductors in the panels,
Because you are putting current on conductive metal like plumbing, gas lines, anything that interfaces with the electrical system.
why not bring 4 wires from the transformers?
If we could start over with the power grid we would probably do that.
Why, if all the load is carried on the grounding (should read grounded) conductor back to the transformer, is it less safe in my scenario? They are all tied together, regardless of weather in the main panel or any sub-panels. Thus, being of equal electrical potential, any current carried by the neutrals/grounded wires is fed into the grounding conductor. The only physical way that I see electricity can back-feed from the grounding conductor into the grounded conductor is if the grounding conductor from the utility's side is damaged or impeded. Otherwise, it has a clear and unimpeded pathway back to its source regardless of if the neutrals are bonded together with the grounds.
Your close to right about this, but even if the POCO neutral doesn't fail you can still develop some voltage drop between the intended grounded conductor (the white wire) and anything connected to the grounding conductor (the green or bare wire). Sparks and shocks can occur as a result.
Again--I'm not trying to be snarky. I know we all read things without the speakers intended tone of voice. Please help me see where I am misunderstanding what I think is basic theory.
You didn't come across as snarky.
 
Thank you all for your help. This makes a lot more sense to me now. I feel kind of stupid for not knowing it before (I knew of the four-wire rule, just not WHY.). Now I understand.

For clarity's sake, let me sum it up as I now understand it:

Essentially, due to voltage drops/losses in the various and sundry connections within the house, even though they are connected at the meter, the grounded and grounding are not necessarily equipotential throughout the house. Thus, electricity (being carried now on the bare grounding as well as the white grounded) could potentially find another route to source via metal casings and other things attached to the groundings via the grounding conductor. (seeing as electricity takes ALL paths back to source proportional to it's resistance). And, even though it isn't shielded, the bare copper conductor in a three-wire service isn't the grounding, it's the grounded conductor.

Is that right?
 

growler

Senior Member
Location
Atlanta,GA
I concede all points relating to what the code says and that it needs to be fixed. The following questions I ask not to be stubborn, but I really want to understand what is happening with the system and why it is dangerous. It was never fully addressed while I was in training, and it seems that my understanding is lacking, so I really want to know. If I seem frustrated, it's because I hate doing things just because "it's what the book says" when it seems to fly in the face of common sense. I have seen many conflicting and contradictory things in the code that even my teachers conceded were self defeating. I just want to know how it makes sense.

" I hate doing things just because "it's what the book says" when it seems to fly in the face of common sense.

When you go to look at a job you price it out to do exactly what they book says and you won't end up being screwed. Haveing to re-do work.

The reason we have the NEC is so that each individual electrician will not have to use his understanding of theory and try to design a safe system. Half the electricians wiring houses don't know anything about electrical theory and can still do a code compliant installation ( they do what the book says).

Even if you could get a 100 electricians and engineers to agree with you on theory you would still have to follow the NEC. Get used to it.
 

growler

Senior Member
Location
Atlanta,GA
I don't have a problem doing what the book says. I have a problem not understanding the reasoning behind it.


I don't understand the reasoning behind all codes either. AFCI breakers I consider a useless waste of money but I still install them where required.

The fact that you would never want the grounding conductor energized except to clear a ground fault should be enough. You brought up the possibility that the grounded conductor could open or be damaged. Look at what happens if this does occur and you have the neutral and ground bonded in a sub panel.

When I was in school many years ago they admitted that grounding and bonding were the least understood and most abused sections of the code.
 
I 100% agree. Just because of this issue I'm diving back into the books to relearn as much as I can. Just goes to show that because you were taught something (or not) doesn't mean it's accurate. Thanks for your input and help.


Sent from my iPhone using Tapatalk
 

ceb58

Senior Member
Location
Raeford, NC
I'd ask the ahj if fishing a #4 CU in would do.....~RJ
~


I asked, but he said I'd ether have to return it to previous condition or run a new 4-wire feeder.

When you jump back in the code book you need to look at 215.6 which takes you to 250.134 excpt. 1 and 250.130 (C)

But I must ask because I'm not sure about the Charleston, SC area but how did you change the meter base to a combo with out getting the POCO involved? Who is the POCO in that area?
 
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