And yet another grounding question

howdy1960

Well-known Member
I bought a subpanel for garage with intentions of having 220 there. I will be running 6 gauge from sub to main box. Distance of under 100 ft. Work electritions tell me wire would handle up to 60 amps but will limit it to 50 amps.
I question the fact that the box came with only one bus bar to hook both nuetral and ground wires to. I will be running a wire back to main neutral bus bar and a grounding wire at subpanel (using a wire that came from a old telephone pole).
I have already installed the 8 ft grounding rod within 5 ft of subpanel.
Since the power comes in on only 2 wires from power company and only one grounding wire at house, my thought is if it works for power company it should work for me. Are my thoughts on right page?
 
(quoted from post at 10:38:52 11/11/14) I bought a subpanel for garage with intentions of having 220 there. I will be running 6 gauge from sub to main box. Distance of under 100 ft. Work electritions tell me wire would handle up to 60 amps but will limit it to 50 amps.
I question the fact that the box came with only one bus bar to hook both nuetral and ground wires to. I will be running a wire back to main neutral bus bar and a grounding wire at subpanel (using a wire that came from a old telephone pole).
I have already installed the 8 ft grounding rod within 5 ft of subpanel.
Since the power comes in on only 2 wires from power company and only one grounding wire at house, my thought is if it works for power company it should work for me. Are my thoughts on right page?
our description is not at all clear to me. Maybe others will be OK with it, but I can't draw a diagram with your words.
 
Most boxes have a place to put a ground buss bar, need to buy separate.

Old telephone wire, that is going to draw a lot of attention as to what screwy deal you are trying to cobble together....... Is this a bare copper wire of enough size to work as your ground (not neutral) wire? Gonna turn a lot of people off right here, as to what you are trying to do.....

Today most locations you need to be running 4 wires, a hot, a hot, a neutral, and a ground. The neutral is used for 120v, the ground is used to protect the whole system from bad things happening, and they have found sorta bad things can happen if you mix up and use the neutral and ground interchangeably. So you need all 4 wires to have a good system. In a perfect world that ground wire will never be needed, but I've never lived in a perfect world....

Since the neutral carries juice when using 120v, it turns out its not a good idea to interconnect it with the ground wire many times over - that makes odd loops that can electrify all your metal surfaces. We used to do that, and it is that way in many many houses, but it's not a good thing, and not the way to do new additions. You need 4 wires, isolate the neutral and ground, only bond at the main box.

It is kinda like a water system, your pipes are all connected to the main source of water to start with, but you need to run hot and cold pipes through the house and can't plumb them together any which way, you need to keep then seperate.

Doesn't matter what the power co has coming into their side of the transformer, that is a way different deal, you need to worry about from the meter on your side. Different setup different needs.

Gets hard to follow what you are trying to do, actually, so hard to answer your question easily.

Paul
 
You did not mention what sort of wire? 6 gauge can be used to carry 75 amps depending on what type.

In regard to amp-carrying capacity . .

#6 copper type TW or UF good to 50 amps

#6 copper type RHW, THW, THWN, USE good to 65 amps.

#6 copper type USE-2, THHW, THHN good to 75 amps.

#6 aluminum good to 60 amps depending on type

In regard to voltage drop - with #6 copper at 100 feet - 70 amp load results in a 2.6%" voltage drop. 60 amps - 2.2% drop. 50 amps - 1.8% drop.
 
There are predrilled holes in your panel to add an isolated ground bar. Screws are self-tappers but it is nice to quickly run a tap through the holes. Scews should come in the ground bar kit.Ground conductor may need a large wire adapter for that bar . { That is just a lug that has prongs that fit into the ground bar holes and takes you large gr condutor.]
 
According the the 2011 NEC code book - "Grounding electrodes must be installed at every building supplied by service conductors." "If one building supplies another building, install a grounding electrode at the second building unless the supply consists of just a single branch circuit."
 
VERY GOOD QUESTIONS somebody must actually be reading all this stuff. FWIW here's my response and as always no warranty since I'm rusty on latest codes.


1) I question the fact that the box came with only one bus bar to hook both nuetral and ground wires to.

That panel is suitable for a main service entrance (assuming a main disconnect somewhere)
as in that situation the Neutral Buss is bonded to the Equipment Ground Buss anyway, so a single common Neutral and Ground Buss suffices. Usually you can buy a Buss and mount it into that panel
if needed and since you're going to use it as a Sub Panel that's indeed what you should do and remember the Neutral Buss must be isolated and electrically insulated from the case/frame and also from the Equipment Ground Buss. The case/frame needs to be bonded to the Equipment Ground Buss.

2) I will be running a wire back to main neutral bus bar and a grounding wire at subpanel (using a wire that came from a old telephone pole).

If running a "wire" remember the two hot Ungrounded phase conductors and the GrounDED Conductor and the Equipment GroundING conductor should be in the same raceway. The Grounding Electrode Conductor (from Neutral out to Grounding Electrode) is often a big bare copper wire if that's what you mean by old telephone pole?????


3) Since the power comes in on only 2 wires from power company and only one grounding wire at house, my thought is if it works for power company it should work for me. Are my thoughts on right page?

No problem if that's your thought, do as you please HOWEVER even if you're not subject to any local authority or no codes have been adopted and there's no inspection whatsoever, the Utility provider often wont connect a service until certain requirements have been met.

FYI the Utility actually has TWO ground wires. On the pole mount transformer the X0 Neutral bushing is earth grounded and then at your service entrance the Neutral is again earth grounded. Yes, they only run 3 wires to your 120/240 single phase three wire system. I've heard somewhere some places are going to start using four wires from transformer to your entrance but that's likely far off.

YES The old system only used 3 wires out to a sub panel (same as Utility did) but the new system requites 4 wires DESPITE THE FACT THERES ONLY 3 FROM THE UTILITY. So do as you please (only run 3 wires to remote sub panel or four per the new NEC) or what any local authority may require or the Utility provider may require.

I will let you or the other gents look up wire ampacity and voltage drop, Im about worn out lol

John T
 
I started the whole mess with a legitimate question, had no idea it would get so involved, but if I learned something myself and helped others I guess it was worth it. Like I've said many times, post a question about electricity or law and everyone crawls out of the woodwork (including me) and everyones an expert and some know a better way then the NEC panel lol

Oh well its all fun and well intended, Im not complaining and appreciate any help I can get or give back.

John T
 
I bought four new boxes last week. Two Square D type QO and the other two are Homeline. All four are 100 amp panels. All came with just one bus-bar and a bonding screw. They all say, right on the outside of the box, which extra bus bars to buy if needed. They all came drilled and tapped to accept two extra bus-bars each.
 
(quoted from post at 07:38:52 11/11/14)

I have already installed the 8 ft grounding rod within 5 ft of subpanel.


NEC now requires 2 ground rods, at least 8' apart.
There might be an exception that I'm not aware of, as this is a newer requirement.
Also it might be required that the #6 ground wire going from the panel to both G rods be one continuos cable. This is true to at least to the first G rod.

Too long retired.

Dusty
 

As Ol'John T has pointed out. Lets not mix up the ground, the neutral, grounded conductor, equipment ground, equipment safety ground, earth.

The neutral is an insulated load current carrying conductor which is held to near earth potential by a ground bond at some or all of the following places. The utility transformer, the meter base or the 1st breaker/fuse panel. Also known as the "grounded conductor" which means it's the neutral.
The ground system is supposed to carry none, zilch, nada, zero of the current operating the electrical devices through the neutral conductor and a live line with 120V, European 240V, 277V and 347 V.
The problem all goes back to the simpler, cheaper grandfathered piece of crap overhead triplex and even some buried three wire service connections. If the utilities and NEC had known then what they know now. A triplex service to an outbuilding with a ground rod connected to the neutral bar would not exist.
Ground and neutral would have been isolated after the service transformer bond. All neutrals would float on an isolated bus bar. Every breaker/fuse panel would be tied to a couple of ground rods and a ground wire to any other breaker/fuse panel common to that utility transformer.
If anybody had looked at the images I posted a couple of days ago from www.hydroone.com . They would have seen the problems with live stock being tingle voltage shocked due to neutral current. Raising the potential of the ground system, water pipes, water basins, cattle stalls above true earth potential.
 
Always been at least a pair rods since I've been
doing it UNLESS there's a better ground source
like a drilled well casing, buried water pipe,
etc. Technically a resistance test can be done
and if there's too much resistance to ground -
even a pair of rods can fail inspection.
 
I'm wondering if it is better to keep the neutral and the ground seperate why so many breaker boxes have a bar like this one linking the two buss bars together.
a173969.jpg
 
(quoted from post at 01:54:56 11/12/14) I'm wondering if it is better to keep the neutral and the ground seperate why so many breaker boxes have a bar like this one linking the two buss bars together.
a173969.jpg

Are you serious or are you putting us on? This has been answered numerous times .
You need to find the person that wired this mess and slap some sense into them.
 
WOW Thank You for all the great responses. I really am attepting to learn.
What I REALLY need to do is win the lottery so can afford a REAL electrition to do it all.

The grounding wire I refer to, from sub to ground (earth), is the coated solid copper wire running from (I presume) the transformer to the ground (earth) removed from a pole I got to use as corner fenceposts.

The wire running from main box to subpanel will be from Home Depot or Lowe's (500' #6 Stranded THHN Black Cable $232) which I will indicate (with colored tapes) as needed. Hopefully my 1" conduit will handle 4 wires.
I will be getting another buss bar for subpanel and hooking grounds seperate from neutrals. I am at a dead stop however when wiring into mainbox as it has only one buss bar, but then again they didn't have grounds when that box was installed some 60 odd years ago (yup it's a fusebox still). Hopefully thus spring I can have that replaced.
 
Stephen, Very good question, easy answer:

"I'm wondering if it is better to keep the neutral and the ground seperate why so many breaker boxes have a bar like this one linking the two buss bars together."

ANSWER

1) Yes indeed MANY breaker boxes have such a "REMOVEABLE" Neutral to Ground Buss Bar tie BECAUSE THEY ARE BEING USED AS THE MAIN SERVICE ENTRANCE PANEL. (some only have one common buss for BOTH Grounds and Neutrals). There the Neural Buss and the Ground Busses are bonded together, ONLY at the Main and never thereafter downstream at sub panels, that's SINGLE POINT GROUNDING.

2) If that same panel is used downstream as a Sub Panel THAT REMOVEABLE TIE IS REMOVED so Neutral and Ground are separate and isolated and dont forget the metal tub/frame needs to be bonded to the Ground Buss.

Got it?? That was a good question

John T
 
"The grounding wire I refer to, from sub to ground (earth), is the coated solid copper wire running from (I presume) the transformer to the ground (earth) removed from a pole I got to use as corner fenceposts."

That's a "Grounding Electrode Conductor" often copper wire say 4 gauge or so. Its good for connecting the Grounding Electrode (driven rod or rods or pipes etc) to the panels Equipment Ground Buss.

"The wire running from main box to subpanel will be from Home Depot or Lowe's (500' #6 Stranded THHN Black Cable $232) which I will indicate (with colored tapes) as needed. Hopefully my 1" conduit will handle 4 wires."

The NEC or a Google search will list the conduit fill requirements as far as how many conductors of what gauge and insulation are permissible in what size of conduit. That being said and NOT having looked up the requirements (NO warranty, only a guess) my guess is bigger conduit would be better.

"I am at a dead stop however when wiring into mainbox as it has only one buss bar, but then again they didn't have grounds when that box was installed some 60 odd years ago (yup it's a fusebox still)."

At the main, regardless if an old fuse panel or a new breaker panel, the Neutrals and Grounds are all tied together anyway, regardless if only one buss or two busses tied together. Its just that when you run out to a sub panel, you carry separate individual Ground and Neutral conductors even though connected to the common in your old panel IE That's NOT a problem for running a sub out of it.

John T Who started this mess lol
 
Then it is all the neutral bar. So you can tie in neutrals neatly on each side where the circuit comes into the box. That panel pictured is a horror.Are there even connectors on those too long unstripped wires?
 
In New York I have seen quite a few entrance service that have the neutral and ground in on the same bar. My insurance company requires an inspection on new or replacement service. Also before utility installs their service they do a short inspection. This is in New York State.
 
To B&D. If everybody is sick of neutrals and grounds, how about talking about Delta and Y generators and transformers. What is the difference and which is better. That would be a long post.
 
(quoted from post at 14:07:54 11/12/14) In New York I have seen quite a few entrance service that have the neutral and ground in on the same bar. My insurance company requires an inspection on new or replacement service. Also before utility installs their service they do a short inspection. This is in New York State.

Nobody said it was wrong for the service entrance panel if located right close to the utility meter.
 
As far as I recall, sharing one bus bar for neutral and ground has always been allowed in NY regardless of what version of NEC was/is being used. I'm talking about the main entrance panel. When I first was wiring in NY - a 1970s code was being used. Now NY is using 2008 NEC (or at least last I checked). Note I'm talking about the state of New York and NOT New York City. NYC has it's own special code.
 
Cas, that's not special to New York only. A Service Entrance Main Panel can have a SINGLE BUSS BAR to which BOTH the GrounDED Conductors and the Equipment GroundING Conductros ALL attach PERIOD. If it has two Bus Bars they are bonded together anyway by a tie bar (as in picture) or other bonding jumper. Its at a sub panel where the two must be separate and isolated. I don't know how many ways this can be said lol Ive posted it myself like 15 years on here.

John T
 
(quoted from post at 22:54:56 11/11/14) I'm wondering if it is better to keep the neutral and the ground seperate why so many breaker boxes have a bar like this one linking the two buss bars together.
a173969.jpg

Where are the romex connectors on that panel?

Dusty
 

The grounding and neutral of a 120/208,277/480 or 347/600 Wye transformer is very similar to a single phase 120/240V system.
The Delta is used to save copper where a neutral is not required as in typical three phase motor loads.
The weird stuff is those corner tapped delta systems that show up in the US.
 
Thankyou for the answer.

For everyone else, I have nothing to do with that breaker box pictured. I just found it with a google search.
 
John T Who started this mess, I'm glad you starting this mess. THANKS!!!
While some of what is/was being stated confused the dickens outa me.
EVERYONE that chimed in was instumental in making me better understand (better yet, comprehend) where my confusion was and drawing a better picture for me to see.
I was treating, and wiring, the sub the same as the main is wired. This will be corrected before any more wire is run. For starters the sub's neutrals and grounds will be seperated with the correct buss isolated from box (need to reread to verify).

Again, Thank You everyone for taking the time to clarify that which my brain wasn't grasping :)
Norm
 
I am working in a new building right now in northern Michigan, New 50 X 40 barn that is 130 feet from the house. A licensed electrician wired it before I got up here and it just passed inspection a few months ago under 2011 NEC code. Michigan just switched last week to 2014 NEC. No ground rods here at the new building. One 50 amp branch panel run off the main 200 amp panel at the house.
#6 copper in PVC conduit, four wires. New panel gets it ground from the twin-electrodes back at the house. To my surprise - this area of Michigan - Alpena County does not let homeowners do ANY wiring on their own houses. The next county over where I live - DOES allow it (Presque Isle County).
 
You're welcome and thanks for the kind words. For sure I (long retired electrical distribution design engineer) recommend connection to a Grounding Electrode at ANY premises electrical service in accordance with that cited below (and even if no local authority demands it, based on my knowledge training and experience, that's still my recommendation that any premises electrical service should be connected to a Grounding Electrode, but if you prefer otherwise, do it at your own risk and peril).

PROVIDED THAT AND SUBJECT TO a local authority has NOT adopted any version of the NEC or any State or other code that says the above,,,,,,,,, Or the NEC or any other code has been superseded so a premises electrical service does NOT require connection to a Grounding Electrode (but so far no one could provide any actual NEC or any other cite saying its NOT required),,,,,,,,,,Or local authority or inspection for whatever reason DOES NOT mandate connection to a Grounding Electrode at your particular building for whatever reason.

In other words, do as local authority says, sure NOT what anyone here including me thinks, feel free to do as you please, no argument from me.

National Electrical Code, NEC Article 250-50

Premise’s Electrical Service

A premise’s electrical service shall be connected to a grounding electrode system consisting of a metal underground water pipe in direct contact with earth for 10 feet or more, if available on the premises, and a supplemental electrode (a rod, pipe, or plate electrode.) An additional electrode shall supplement the buried water pipe electrode

Best wishes, wire it however you please if you feel safe and secure.

John T
 
(reply to post at 08:53:33 11/13/14)
Generally a deep buried ground plate will out perform any ground rod. iirc you have several backhoes ?
The idea is to set up a ground plane with "ground rods" at the utility, the transformer pole, the utility meter ,every electrical panel and every water pipe interconnected. To obtain a ground plane or area with as similar as possible potential with relation to true earth.
 
Glen, where I did most of my practice (and I believe this was what NEC said then and still now) WE BONDED TO EVERY "READILY AVAILABLE" GROUNDING ELECTRODE. Those were perhaps, Metal gas & water pipes,,,,,,,,Building or foundation structural steel,,,,,,,,"Made Electrodes" like driven into earth copper rods. We drove one rod and measured the resistance and if it failed we drove another rod 6 feet away, but then if both failed, we didn't have to drive another. Theres no way we would ever install an electrical service and NOT connect to a Grounding Electrode where I practiced. Perhaps other jurisdictions are different, although I don't understand why they wouldn't want to connect the service to a Grounding Electrode??? To each their own

John T
 

You got it John T.
The specs for grounding and bonding for new dairy barns in particular keeps the entire site very close to the same voltage and very close to true earth potential.
Everything metal is tied together with #6 copper.
Still the problem with Bubba operating vacuum pumps etc with no ground or bond what so ever . My favourite is replacement 120V cooling fans on 240V milk coolers with no neutral back to the panel. Bubba just ties the 120V fan motor neutral to chassis and wonders why the cows have become jumpy.
 
Helped build once.
We ran a 4/0 bare conductor around the outside perimeter of the building. Drove a copper platted steel ground rod at every other column. And Thermal Welded the rod, wire, and column all together.

Dusty
 

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