# A few electrical questions



## Quattro (Mar 12, 2007)

My main service panel has one neutral/ground buss bar. It's full, and I need to clean it up because there are instances where grounds and neutrals are combined under one screw. This passed inspection when I bought the house, but I have been finding lots of things that our inspector missed...
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QUESTION 1:* Can I buy a separate ground bar, screw it to the main panel, and move all the ground wires to it? That will free up lots of space on the neutral panel so each circuit can have it's own screw. 
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QUESTION 2:* Should that ground bar be attached to what will then be the "neutral only" bar with a heavy-gauge jumper?

Thank you!


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## Quattro (Mar 12, 2007)

removed to clarify


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## JoeD (Mar 12, 2007)

1. If by tandem breaker you mean one that takes up only one slot then no tandem breaker. A double pole 240 volt breaker would be fine. In some case they are required.

2. Yes can do that. One neutral per screw is a requirement for neutral wires.

3. The additional ground bus has nothing to do with the fact that the sub panel must be connected with a proper size ground wire. The ground bus itself needs no connections. It grounds to the frame of the main panel when it installs.


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## Quattro (Mar 12, 2007)

Hey JoeD, thanks for the help. 

1. I meant 2-pole breaker, with a connected handle (forgot the term for this).

2. That's what I thought...will do.

3. So the sub-panel does not need a ground feeder wire running to the main panel ground bus? The sub-panel grounding bus is (obviously) screwed to the sub-panel box itself.


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## Quattro (Mar 12, 2007)

OK, a little more info:

- taking a voltage reading between the two circuits in question, I get 245V. According to another resource, this means the circuits are on opposite phases, and I shouldn't have a problem with the shared neutral. Is this correct?

Now, looking at the existing neutral/ground bus on the 20-space main panel: 

- there are only 16 or 17 locators. How the heck is a guy supposed to have enough spaces on the bar to accomodate 20 circuits? Even if only 1/4 of the breakers have shared neutrals, that's still 15 inidividual spaces needed for neutral landings. That leaves 1 or 2 for ALL the ground wires? This just doesn't seem right. 
Looking more closely at the ground/neutral bar reveals there are smaller holes right beneath the regular holes for securing the neutral wires. But, as far as I can tell, there is no way to secure a ground wire in these smaller holes. What are these for? I might have to snap a picture to reveal what I'm talking about here...if this is too confusing.

Thanks for the help.


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## Quattro (Mar 13, 2007)

Pictures!

The overall main and sub panel:






A little closeup of the wire entries:





The FULL neutral/ground bus:





Another shot:


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## Quattro (Mar 13, 2007)

The "mystery holes" on the neutral/ground bus under the regular screw-clamp holes:


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## glennjanie (Mar 13, 2007)

The sub-panel is connected to the main with "compression fittings" which I personally don't trust for grounding. I wold keep the big green wire and move it to the higher (horizontal) bus bar along with the other ground wire that is connected to the vertical one.
I like the grounds being tied to the copper pipe but I would also want a driven ground rod outside.


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## JoeD (Mar 13, 2007)

The sub panel needs a ground wire from the main panel. I thought you meant connecting a wire from the existing ground bus to the new one you want to install in your main panel.


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## JoeD (Mar 13, 2007)

I also see a couple of breakers with two wires under the screw. Some breakers are rated two wires, some are not. I don't know which type yours are but that could be ans issue if they are not two rated.


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## Quattro (Mar 13, 2007)

JoeD said:


> I thought you meant connecting a wire from the existing ground bus to the new one you want to install in your main panel.



This is what I meant! I need more room in the existing ground/neutral bus in the main panel. There isn't enough room for each neutral to have it's own spot. Not even close! Why did they do this?

And you're right on the double-wired breakers. There are two. Both were done by (I assume) the previous owner or original owner.The one on the mid-left is the doorbell transformer. The upper right is the washing machine and something else. I need to trace what the "something else" is. There is an open slot at the bottom left (breaker, no wire), so it can me moved there I suppose.

Thanks!


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## Square Eye (Mar 14, 2007)

The green wire is the ground connection from the main panel to the sub panel. And the ground wire connection to the grounding rod is made in the meter base.

A ground jumper from the original grounding buss would be necessary to the new grounding bar as the main panel doesn't seem to be bonded.


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## glennjanie (Mar 15, 2007)

One more suggestion, Quattro:
You could move the wires from the sub-panel's vertical bar to the horizontal bar (grouping your bare ground wires again), then move that vertical bar over to the Master panel. That should give you sufficient spaces. 
I still insist the green wire needs to go to the sub-panel horizontal bar. 
I can see a large bare wire comming out of the master panel, possibly going out to the meter base and the ground rod.
Glenn


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## Quattro (Mar 15, 2007)

I have been told over and over that the sub-panel ground and neutral should NOT be connected. The neutral floats in that panel, and is connected by #6 to the main panel neutral buss. 

The main panel has a ground rod AND a bundled ground attached to the nearest copper pipe (which is connected to the rest of the copper pipe in the house). 

Square Eye: how would I know if the main panel neutral buss is bonded or not? Thanks!


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## JoeD (Mar 15, 2007)

The ground bus should be bonded to the metal of the panel box. There should not be a need to jumper the two busses together. If the original bus is not bonded then it was meant to be a neutral buss only and a ground bus should have been installed separately.


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## Quattro (Mar 15, 2007)

If by "bonded" do you mean screwed to the panel with a long brass screw? In that case, it is bonded.


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## glennjanie (Mar 16, 2007)

A bonded panel has a piece of rigid conduit through the side where your ground wire comes out and goes to the ground rod; there would be a bushing on that conduit that is screwed tight against the box and has a seperate hole on the side of it for the ground wire to go through, and a screw to tighten down on the wire. Its called a bonding bushing and it grounds the box independent of the grounding bar. 
The connection to the sub-panel appears to be made of EMT conduit with connectors attached by a screw in the side of them. This is not acceptable for a grounding path between the two panels. Therefore, the green wire still needs to go from neutral/ground buss bar to the other neutral/ground buss bar.
Glenn


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## Square Eye (Mar 17, 2007)

I suppose the same words could be interpreted many ways.

A newer main panel will have a Bonding screw included with it. Your panel may be have been manufactured before this was the case. The bonding screw passes through the neutral buss and attaches directly into the back of the panel. This is necessary at the main panel. The option is there to use this same panel as a sub-panel by not attaching the bonding screw. This leaves the neutral floating in the panel and requires a ground wire from the ground bar back to the main panel. 

In your case.. I don't know wether your panel's neutral buss is bonded to the panel or not. It looks like an older panel and I really can't tell from here. A neutral jumper won't hurt a thing.


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## Quattro (Mar 18, 2007)

Hey guys,

yes, the main panel is screwed to the back of the panel. It's a brass screw. I'm going to look around for a good place to mount that auxillary ground buss now!


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## AndyD5 (Mar 29, 2007)

You're looking at an older style square D panel you are correct that each ground an neutral should have it's own screw position  you can put in a secondary bus for the neutrals they have them that clamp ontop the existing or just screw right into the frame of the panel a branch circuit just needs grounding period it doesn't have to be grounded back to the main panel it can be grounded to a nearby fully functional coper water line anywhere in the house my branch box is ground clamped to the supply line to the toilet nearby.  I don't know the codes there but here the water supply line is the ground in every house. the stranded heavy guage wire provides ground to the main panel.


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## AndyD5 (Mar 29, 2007)

they are correct about the bonding issue too the gray plastic should not ever have been used on a metal panel  nor should that fitting between the boxes been done that way either the plastic stuff is for low voltage and outside underground light fixtures and things of that nature


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## Square Eye (Mar 29, 2007)

AndyD5 said:


> a branch circuit just needs grounding period it doesn't have to be grounded back to the main panel it can be grounded to a nearby fully functional coper water line anywhere in the house my branch box is ground clamped to the supply line to the toilet nearby. I don't know the codes there but here the water supply line is the ground in every house.
> 
> the gray plastic should not ever have been used on a metal panel  nor should that fitting between the boxes been done that way either the plastic stuff is for low voltage and outside underground light fixtures and things of that nature




Where in the NEC does code allow grounding to any nearby water pipe?

What if the pipe is plastic between the grounding point and the outside?

NEC allows PVC pipe on service entry, for conduit in most damp locations and CERTAINLY in underground applications from the service entry to the run out to the garage.. 75% of newer homes have PVC from the meter base to the panel. Code requires rigid conduit from the meter base up in overhead service feeds.


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## AndyD5 (Mar 29, 2007)

that is why I said copper water line  of course things are different different places here in AZ your meter head is usually mounted right into the panel box only older houses are seperated with the overhead most of AZ is underground personally I check all grounds before assuming they are ground.  in all 28 years living in Arizona I have not seen a single house that was grounded in any way other than a clamp behind the hose bib closest to the main shut off valve from the house side of the water meter.


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## petey_racer (Mar 30, 2007)

AndyD5 said:


> m that clamp ontop the existing or just screw right into the frame of the panel a branch circuit just needs grounding period it doesn't have to be grounded back to the main panel it can be grounded to a nearby fully functional coper water line anywhere in the house


THIS IS INCORRECT AND UNSAFE ADVICE! Please DO NOT follow it.

You are NOT permitted to simply ground a circuit to a near by water pipe. 
You can use a water pipe in VERY limited circumstances. And "anywhere" does NOT fit this description.

Also, an ad on ground bar should NOT be used for neutrals. The ground bar simply screwed to the back of a panel is NOT designed to carry current. Neutrals always carry current. Grounds only carry current under fault conditions.

If you ad on a bar move grounds to that bar and use the existing neutral bar for any neutrals.


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## petey_racer (Mar 30, 2007)

AndyD5 said:


> in all 28 years living in Arizona I have not seen a single house that was grounded in any way other than a clamp behind the hose bib closest to the main shut off valve from the house side of the water meter.


OK. You are likely looking at the water bond. NOT a service ground.


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## inspectorD (Mar 31, 2007)

Well Petey....(deep subject) you opened the box... 

What is the difference between grounding and bonding for those that think it is the same wiring....?

Sorry to put you on the spot but.... you are the code guru.....


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## petey_racer (Mar 31, 2007)

Well,I really did not want to get involved in this thread seeing as it had been covered nicely. I just really felt the need to address some of the erroneous and dangerous advice give recently.

Service grounding (a word I hate by the way) using grounding electrodes DOES NOT "ground" anything. Many folks think this has something to do with the safety ground and the third prong in receptacles. It does not.
Grounding & bonding are VERY complex issues and there are reams of information written. For the real purpose of the grounding electrode system in your house you can go to a site such as Mike Holt's or ECN and read some newsletters. I'll link one below.

For the purposes of that particular statement; service grounding by a METALLIC water pipe entering the structure, for new work and renovation/replacement. These rules are not retroactive. 
If there is a metallic water pipe entering the building, AND it is in contact with earth at least 10' out, this pipe MUST be used as the primary grounding electrode. You must attach a GEC (grounding electrode conductor) within 5' of where the pipe enters the structure. Also, any removable meters, plastic filters, etc, that can/do breaker the electrical continuity of the piping system,  must be jumpered around. 
This GEC must be sized according to NEC Table 250.66
Even with this electrode, a supplemental electrode(s) must be installed. Typically this is a ground rod, or two, driven outside.
In the above case, no additional water bond is required. The GEC serves both purposes.


If the water pipe entering the house is non-metallic, then we still must BOND the metallic water piping system. The bond wire is also sized by Table 250.66.
See NEC 250.104(A)(1)


http://ecmweb.com/mag/electric_grounding_vs_bonding_2/index.html


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## Quattro (Apr 2, 2007)

Thanks for the info, petey_racer.

I wasn't planning to move neutrals to the new bar...just grounds. In fact, I'm going to be doing this tonight, so I'll let you know how this went.

Thanks.


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