Grounding & bonding prevents Arcing

[MD84]

Got it, I agree.

And my point is simply this.

We bond around service raceways and concentric KOs to prevent a more spectacular arc from happening than the ones shown in my pictures when there is a ground fault.

Even below 600 volts.

I am not saying in any way that there some sort of continuous arc, I am pointing out bonding is often done to prevent arcs during a ground fault.

 

[jaggedben]

Perhaps the point is really just semantic. But if people think that everything that has been said about arcing in this thread can be accurately summarized and described by the phrase 'bonding prevents arcing', then we'll just have to agree to disagree. I think kwired gets what I'm saying.

'Bonding prevents arcing'

does not equal

'Bonding causes arcing in some circumstances but we do it so that the arcing is predictable and controllable instead of unpredictable and uncontrollable, and then there's also lightning and high voltage applications and applications not under the NEC, and blah blah blah blah.'

I still think the home inspector probably does not know what he's talking about.

 

[jaggedben]

I'll just add...

Probably 90% of the arcing I have regrettably witnessed in my career would NOT have happened if a bonded object involved were not bonded. I am of course not saying that such objects should not have been bonded. Just that if you don't understand how bonding causes arcing then you shouldn't be doing electrical work.

 

[Ingenieur]

I'll just add...

Probably 90% of the arcing I have regrettably witnessed in my career would NOT have happened if a bonded object involved were not bonded. I am of course not saying that such objects should not have been bonded. Just that if you don't understand how bonding causes arcing then you shouldn't be doing electrical work.

of course
because there would be no ground fault return path!

you would not even know you had a fault until someone touched the faulted frame
then you would have a ground path
thru the person

:?

 

[kwired]

Signs of?

Obviously it arced and spit sparks out.



:slaphead:

Why so rude? Just trying to figure out exactly what you were getting at. You link to a thread with 104 posts and say nothing more so I'm supposed to guess which of the 104 posts I need to look at, or assume the first post is the topic and go with that.

I have seen similar arcing around locknuts as well as bolted joints in gutters/wireways before, it is not because of a total lack of bonding it is because there wasn't solid enough bonding for the current that was imposed at some point.


Was interesting to read through some posts by a few members that are no longer with us though.

 

[Sahib]

You need to be content with what it does rather than what it is. In that respect, you need to know that once an arc is established between conductor and ground, OCPD may not be always able to clear it.

Can you elaborate further on this? Im a bit dull in that regard

Remember arcing ground in an ungrounded system in early days and the extensive damage the arc causes with OCPD remaining a mute spectator for too long a time.

 

[mbrooke]

Remember arcing ground in an ungrounded system in early days and the extensive damage the arc causes with OCPD remaining a mute spectator for too long a time.

Correct, but in a grounded system such transient over voltages do not happen.

 

[Sahib]

Then what is AFCI for?

 

[kwired]

Then what is AFCI for?

Is a profit making tool for those that manufacture them:lol:

 

[K8MHZ]

Then what is AFCI for?

Making stockholders happy.

My state caught on and does not require the silly things.

 

[mbrooke]

Then what is AFCI for?

Meeting earth fault loop impedance requirements in none IEC countries. Or at least that was the inspiration. :happyno:

 

[romex jockey]

@ Mr. MBrooke...

~RJ~

 

[mbrooke]

@ Mr. MBrooke...

~RJ~

:lol: I take you got it?

 

[romex jockey]

I only wish more would Mr MBrooke

~RJ~

 

[mbrooke]

I only wish more would Mr MBrooke

~RJ~

That perhaps is the ultimate key, not only for us but the entire planet as AFCIs are going global.

 

[don_resqcapt19]

Remember arcing ground in an ungrounded system in early days and the extensive damage the arc causes with OCPD remaining a mute spectator for too long a time.

The damage was not directly caused by the arc...it was caused because sometimes an arcing ground fault on an ungrounded system would cause transient over voltages that would damage equipment.

Maybe you are thinking of the arcing "burn downs" that destroyed switch gear on 480Y/277 solidly grounded systems. That issue led to the rule in 230.95 that requires ground fault protection for service disconnects rated 1000 amps or more. That has since been expanded to also apply to feeder and branch circuit OCPDs rated 1000 amps or more on that type of system.

 

[Sahib]

The damage was not directly caused by the arc...it was caused because sometimes an arcing ground fault on an ungrounded system would cause transient over voltages that would damage equipment.

Maybe you are thinking of the arcing "burn downs" that destroyed switch gear on 480Y/277 solidly grounded systems. That issue led to the rule in 230.95 that requires ground fault protection for service disconnects rated 1000 amps or more. That has since been expanded to also apply to feeder and branch circuit OCPDs rated 1000 amps or more on that type of system.

That is the change in what an arc does in ungrounded and grounded systems and observe

You need to be content with what it does rather than what it is. In that respect, you need to know that once an arc is established between conductor and ground, OCPD may not be always able to clear it.

 

[Sahib]

So to sum up how grounding & bonding prevent arcing:

Grounding can prevent arcing in an ungrounded system and so ungrounded system to be converted to grounded system unless other precautions are taken.

Bonding can prevent side flashes irrespective of whether it is grounded or ungrounded power system.