To bond or not to bond neutral and ground in new electric service panel?

[Tractor Seabee]

Great, we are getting consistent and accurate info for an OP. Neutral, bond, ground, grounding conductor, bonding are all interrelated terms but have definitive definitions. Even some electricians have problems with those terms. There is a manual called "Grounding and Bonding" by Soares that is primary training text for electrician training, universally accepted. This is such a big and highly technical subject the manual is 1" thick. When I was doing construction inspections that was in my truck all the time. Had another one in the office.

Generators are another part of the subject as they are handled differently depending on how used. Ground or Don't Ground is the question. Too many variables to make positive statements except stand alone portables on a job site are not grounded, normally. Safety Inspectors are often confused on this.


Ron

 

[s219]

220v requires 3 wires. 1 called ground & 2 "Hot wires. Nothing more is needed.

For the main service entrance, yes. But for any sub panel or feeder hanging off the main panel, they require a ground wire to tie into the main ground. So you should see 4-conductor (called 3 plus ground, just to confuse everyone) running to the sub panel.

 

[dweitzel]

This would lead some strange voltage splits, that is, your 240V won稚 divide evenly into 2 - 120v legs.

Thank you Coby, that was the exact information I was looking for. Guess I need to get the correct screw and get it installed ASAP before any additional circuits are added.

Thanks again for all the great info and explanations.

Just a bit of clarification, this entrance panel is about 220' from the meter base, and it acts as the main disconnect. No disconnect required because the panel is on the inside of an outside wall.

 

[dweitzel]

One other question, is if the ground and neutral bar is "bonded", then does it matter in reality if the grounds and neutrals are separated on different ground and neutral bars in the panel? I know it's good practice and probably code to have them separated.

 

[Rock knocker]

One other question, is if the ground and neutral bar is "bonded", then does it matter in reality if the grounds and neutrals are separated on different ground and neutral bars in the panel?

Which panel?

In the panel where ground and neutral are physically bonded, then yes, white and green wires can be terminated on the same buss. Everywhere else, no they cannot.

 

[MossRoad]

One other question, is if the ground and neutral bar is "bonded", then does it matter in reality if the grounds and neutrals are separated on different ground and neutral bars in the panel? I know it's good practice and probably code to have them separated.

It doesn't matter electrically speaking, as they are all physically attached to each other. However, I don't think its a good idea. 1. It might be against code. 2. It looks bad (organization in a box makes it easier to troubleshoot, add, remove circuits later). 3. If for some reason you ever add something upstream of that box, like a disconnect at your meter, or an outdoor panel, etc... that first panel will become your service disconnect, and you'll have to separate those neutral and ground busses in the first box.

I'm a big fan of a service disconnect just below the meter. That way, if there's a fire, you can kill the whole house from outside. Or if you want to work in the box to add a circuit, troubleshoot, etc... you can kill the power in the whole house and not worry about bumping those hot wires at the top of the box.

 

[dweitzel]

Thanks Moss, all makes sense now. Yes, I've always separated the grounds and neutrals, just wondering. All good info.

 

[GLyford]

I had my panel replaced (main disconnect) and the electrician mixed up all the grounds and neutrals. A year later, and a different electrician was working in the box and was very irritated that first one hadn't bothered to keep them sorted.

 

[grsthegreat]

I don't see a ground wire from the house out to the barn sub-panel. Just two hot one neutral for 100 amp 240 service. Does that change anything?

I know the barn was wired by amateurs some 55 years ago, and I think electricity was added to the existing house in the 1920's. An outlet tester at some locations shows combinations of lights that aren't on the list of good/bad responses.

I had to remedy something that made the chrome-plated kitchen percolator tingle when touched. That could have been deadly if someone added a longer cord and filled it at the faucet while plugged in. I suspect electricity bleeding to ground somewhere was the cause of major pipe corrosion, galvanic action, that seems to have ended after I got a few things wired like they should be.

This farmhouse is out in the country, never had a building inspector sign off anything. Dad's advice was just bulldoze the place when he was gone, too much was beyond repair. Now I'm getting old and telling the same thing to my kids. It's a cute little farmhouse (and outbuildings) but everything needs attention continually to stay functional.

it use to be that all buildings served from a main house only needed 3 wires and then drive 1 0r 2 grounds at 2nd building. this worked for many many years. now the current thinking is not to allow for a great distance between ground bars which can cause an issue with with potential voltage differences between ground rods. if its existing and has a ground rod or 2, than you dont need to do anything. in these older panels the grounds and neutrals are usually also tied together.
now come to current panels after aprox 2011. we now run 4 wires to outbuildings for 240 volt service. we still add either a ground rod or uffer ground, and we SEPARATE the ground and neutral buss bars.

ONLY the very first panel fed from utility power that has a main breaker gets the ground and neutral connected together. all panels after this one have to have grounds and neutrals separated. all sub panels have to have a neutral AND a ground wire supplied to it. its that simple.

oh..im an electrical contractor. nearly 40 years and counting

 

[California]

it use to be that all buildings served from a main house only needed 3 wires and then drive 1 0r 2 grounds at 2nd building. this worked for many many years. now the current thinking is not to allow for a great distance between ground bars which can cause an issue with with potential voltage differences between ground rods. if its existing and has a ground rod or 2, than you dont need to do anything. in these older panels the grounds and neutrals are usually also tied together....

oh..im an electrical contractor. nearly 40 years and counting

Thank you! That describes what I see. So I don't have an immediate problem, but do have a system that is grossly out of conformance with modern specs.

Not only do I have that obsolete layout, worse is everything at both panels is Federal Pacific- a company now out of business because their stuff caused fires. I'm careful to never load any circuit to near breaker capacity. Thankfully this isn't our primary residence, we spend most of our time now at the ranch but have a house in town.

Photo: Worst example of how obsolete (and amateurish) the farmhouse wiring is, under the house in an area made inaccessible by a later remodel. I hope the wiring in the walls isn't like this.