ECN Forum Forums Code Related Discussion NEC & other Code issues Gas bond?'s

Now I'm going to throw out an analogy here, and don't go ape on me if your opinion might be different.

We bond to keep the potentials the same. Which makes sense to bond a gas,(although I have gripes about how I am being made to do it lately.) seeing that we bond water, and hot water. (If metalic) We bond the neutral to ground, because we want to keep the potential low there too. (Relitive to earth) And, so we don't end up with a floating neutral causing over-voltage in every multi-wire circuit. And we ground because we want to (essentially bond) the exposed equipment surfaces and other bonded items also at the same potential as the earth. We want to keep everything the same and low, voltage potential wise, Right?

So if all of this is true, and EVERY faucet and stove out there is metal, why do we not bond everything andban plastic piping sytems?

I do not think that there is anyway to connect the neutral to earth in a way that can limit the difference of potential by very much for 120 volt faults.

Take a ground rod and bang it into the earth, now connect a conductor to it from a 15 amp 120 volt source.

Will it trip the breaker?

If you where barefoot would you touch this ground rod?

As I understand it we connect the neutral to earth for two reasons. Lightning and a power company fault that sends high voltage toward your home.

How about this, we have the plumbers always use plastic water and gas lines. For a grounding electrode we drive rods or use Ufers.

Bob

Hey Bob,
I,m having fun, so bear with me while we play, "Pick apart the other guy!" A Code Forum favorite Game Show.... Kidding!

Now is there a load between the source and the rod? The breaker just might trip with no load. Would I touch it, with load I might, wouldn't let a child do it... No load, no! It might be a 500F degrees, or 120+/- volts, or somewhere in between. (Depending on soil conditions between the rod and the rod at the transformer.)

Survey says.... Bzzzzt!

Bob, just having fun. But, I have seen a short clear on a water not bonded to a service, and several concrete floors, not bonded to the service. Because there was a rod somewhere near the trannie feeding the whole mess. Most times the resistance is too high to do it, sometimes it isn't. So, yeah I think we ground for the two reasons you mentioned , and the one I did. (Potential differance to earth)

Now the plastic thing... I still have to drive two 8'x5/8" rods or a ufer anyway! I have to do a ufer for any foundation work over 20' continous! Even after driving two rods, if the foundation work is later. But not the other way, if I have a ufer, don't need rods. Welcome to my world.

Ok, where does "ufer" come from? It is a term I have used for years and have put many in, and have no idea.... CEE = Ufer?

And while I'm at it. IMO what is "IMO"?

IMO In My Opinion

Ufer as in George Ufer a guy who designed that system during WWII for buildings in the desert

Mark, this link should answer your question: http://www.scott-inc.com/html/ufer.htm

Thank you gents, I have learned something today!

LOL

I can kick things around and disagree without getting upset.

Very unlikely a ground will open a 15 amp breaker from a 120 volt source unless there is already a good load on it.

The combined resistance resistance of the rod at the service and whatever electrodes are connected to the power company source would have to be less than 8 ohms. If you got down to 6 ohms it would take some time to trip, to get a 'fast' trip IMO you will need to get down to 2 or 3 ohms.

IMO you would need some unusual conditions to have less than 8 ohms total.

Bob

In Calif.-So. Calif. Gas Co. territory: "The Gas Company" says NO don't bond to our stuff, even within the building. As of about three years ago, that statement changed because "The Gas Company" said, we are now using a dielectric fitting on new installations; you may bond the building gas piping. So, we bond.
Usually it's at the water heater: one Bonding Jumper from the ground bar to Gas , CW, HW in one convenient and accessible location.
Oh yeah, Any new foundations in conjunction with a new or upgrade service, even in an addition, then we get a UFER.