Bonded/Grounded

[JamieK]

I see these terms all the time, but what exactly do they mean and whats the difference? Thnaks!

 

[oleguy]

bonded/grounded means that the ckts are tied to ground.the ground has continuity from ground buss at service to end of ckt.someone might have a better definition but bonding/grounding is the same term.

 

[GeorgiaHybrid]

Jamie,

I'm sure that the electrical wizards will chime in on this one but what you basically have at your load center is an external ground (ground rod) and a neutral from the power company. They are hooked together (bonded) at this point. Usually you have a grounding lug that your neutrals and ground will tie into and the "bonding screw" (usually green) will make a connection between the neutral and the grounded box.

Any additional sub panels that are downstream of the main panel (and that are in the same building) should have the neutral and ground separated (not bonded together). That means 4 wires from the main panel to the subpanel (2 hot legs, 1 neutral and 1 ground) and the bonding screw in the sub panel should be removed. This will make the neutral on one bar and the grounds on another that is attached (grounded) to the box.

They will have a very fancy explanation for it but from a dummies point of view, that is what they are talking about.

 

[sberry]

I agree that someone may have better explanation but for our purpose here, bond is tyeing something together, a clamp or screw to provide continuity, grounding is providing a pathway via a raceway pipe or wire back to the source that it originated from. The transformer via the service entrance. A pool installation for example calls for all the metal in the adjacent area to be bonded together with number 8 wire, all the rebar, pump parts, anything metal.

 

[sberry]

NEC does have definitions.

 

[kbs2244]

Has anybody ever noticed the wire that goes down the side of a power pole and into the hole when it is planted?

Sure looks like a "Ground" to me.

 

[oleguy]

and you will be right.that is tied to the neutral of the transformer.

 

[DHS]

What are the dangers in bonding the ground and neutral in a sub panel in a separate building?

 

[oleguy]

if you loose the neutral,then you run the line to neutral load through the ground.the ground is a protection only not ment to carry the load.and the possibility of a ground wire bieing removed or a light fixture having a high potential on the metal parts .sure someone will explain it a little better.

 

[sberry]

You want the neutral currents to be carried down the insulated wire you intend them to be on. If this is a 4 wire feed the electric wouldn't be choosy, some would travel via the ground. In a 3 wire fed panel or service it MUST be bonded for a fault (short circuit) return path.

 

[sberry]

I want to add something, one of the concerns with bonded N's is that current may flow over other interconnected metal pathways, gas lines, water lines, phones, etc. Anything metal between buildings. May even carry faults thru these connections.

 

[Nostraquedeo]

2005 NEC

Bonded - The permanent joining of metallic parts to form an electrically conductive path that ensures electricalcontinuity and the capacity to conduct safely any current likely to be imposed.

Grounded - Connected to earth or to some conducting body that serves in place of earth.