Bonding and grounding

G

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Consulting Electrical Engineer - Photovoltaic Systems
A comment I frequently see on these forums is that someone does not understand the difference between bonding and grounding. I think I do, but allow me to test my understanding:

Bonding: The electrically connecting of two or more electrical nodes.
Grounding: The bonding of one or more electrical nodes to a GEC or EGC.

Is that a correct distinction, or am I missing something?
 
What is your definition of nodes? I don't think that terminology is used in the NEC is this context.
 
I believe bonding is limited to connecting conductive materials not intended to carry current, not any electrical node.

(Though 'bare hands bonded on' is a term for a type of live high voltage work. Though again the bond is not intended to carry circuit current, but only to carry parasitic current...)
 
If it does not directly connect to a grounding electrode, it is bonding. Grounding is only the direct connection to a grounding electrode.
 
don_resqcapt19 said:
If it does not directly connect to a grounding electrode, it is bonding. Grounding is only the direct connection to a grounding electrode.
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That is the way I think of it. The connection directly to the earth is grounding. Everything else is bonded together and is eventually connected to the earth. Part of the problem is the way that the word grounding is used in the NEC for example Equipment Grounding Conductor. There have been many attempts to change this to a more correct term of equipment bonding conductor.
 
My take (for building wiring, as opposed to electronics, say):

Bonding: providing a low impedance connection between two conductive objects, not for the purpose of carrying current during normal operation, but to ensure equipotential or to carry fault current.

Earthing: connecting to the earth.

Grounding: an ambiguous term that means either earthing or bonding depending on context.

Cheers, Wayne
 
infinity said:
What is your definition of nodes? I don't think that terminology is used in the NEC is this context.
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It's not my definition; it's an engineering term that simply means a point in an electrical circuit.
 
Bonding - to create a equipotential between non normally energized metal parts.

Grounding - the term used when connecting the nonnormally energized metal parts to earth.

It has been my opinion that the term EGC should be EBJ (Equipment bonding jumper). It connects the non-normally energized metal parts to earth via GEC but it conflates some of it's purpose.

Would it's primary purpose be a ground fault return path or to bond, on the load side of equipment, the metal parts. Thus ensuring there is no voltage difference and therefore shock hazard when touching. Creating a equipotential between all electrodes, metal piping (likely to become energized) and metal housing/holding electrical conductor and equipment.
 
electrofelon said:
I a just saying they use the word "grounding" often when they should be saying bonding
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Yes it does... I made a large number of proposals for the 1996 code to replace equipment grounding conductor with equipment bonding conductor. Those proposals received a majority vote in CMP 5, but one vote short of the 2/3s majority required to make a code change.

However just because the NEC does not understand the difference between grounding and bonding, does not make my statement wrong.
 
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