Grounding & bonding prevents Arcing

[JDB3]

A "home inspector" inspected a home that I wired a number of years ago. In his "report", he stated that bonding and grounding of the HVAC system would help prevent "arcing". He also stated that the whirlpool tub was not GFCI protected (the GFCI protection is in the master closet, closest location available for the tub. What does it take to be a home inspector? :?

 

[iwire]

A "home inspector" inspected a home that I wired a number of years ago. In his "report", he stated that bonding and grounding of the HVAC system would help prevent "arcing". He also stated that the whirlpool tub was not GFCI protected (the GFCI protection is in the master closet, closest location available for the tub. What does it take to be a home inspector? :?

It's great that electrcians never make mistakes or have misconceptions about grounding and bonding.

 

[chris kennedy]

What does it take to be a home inspector? :?

Two months of unemployment and willing to take any job you can get???

 

[iwire]

Two months of unemployment and willing to take any job you can get???

Here in mass it takes two years working under another licensed HI and required schooling.

 

[chris kennedy]

Here in mass it takes two years working under another licensed HI and required schooling.

Interesting. Sorry to say down here we have very little respect but those guys are certainly good for our business.

 

[iwire]

Interesting. Sorry to say down here we have very little respect but those guys are certainly good for our business.

You have read enough posts of mine to know I am clueless about why electricians get so bent out of shape about HIs that make work for them. It seems they are so interested in putting them down they stop carrying about making money.

It seems very odd to me especially when we see professional electricians ask some pretty basic questions on this forum or even engineers that think the difference between a grounded and ungrounded PV system is if it sits on the ground or the roof. hmy:

 

[MD84]

Grounding and bonding does help prevent arcing.

 

[jaggedben]

Grounding and bonding does help prevent arcing.

Um, seriously?

 

[iwire]

Um, seriously?

Yes, it is exactly why bonding is required in many cases.

 

[Ingenieur]

Um, seriously?

yes
in mining you can have 2 machines powered by a trailing cable
due to grounding/bonding Z differences each may have a different frame potential
if they touch current will flow and an arc may result
we test for this with a R and vom
limit is 1 A 100 mV 0.1 Ohm
in a classified/gaseous environment could be disasterous

Page 3-7 and 3-8
http://arlweb.msha.gov/READROOM/HANDBOOK/PH93-V-7.pdf

 

[kwired]

Grounding and bonding does help prevent arcing.

Depends on what perspective you are looking at something from.

Bonding items in close proximity to one another will put them at same potential and will reduce arcing other then for extreme high voltage incidents - lightning may still arc between objects that are otherwise bonded together.

Bringing faulting an ungrounded conductor to a grounded and bonded object will likely still have some arcing at the fault location.

On the other end of perspective - if you have a spark electrode intended for ignition of a gas - lack of bonding sometimes may prevent desired arcing.

 

[MD84]

Depends on what perspective you are looking at something from.

Bonding items in close proximity to one another will put them at same potential and will reduce arcing other then for extreme high voltage incidents - lightning may still arc between objects that are otherwise bonded together.

Bringing faulting an ungrounded conductor to a grounded and bonded object will likely still have some arcing at the fault location.

On the other end of perspective - if you have a spark electrode intended for ignition of a gas - lack of bonding sometimes may prevent desired arcing.

That is an interesting perspective. I think that bonding in the case of lightning still helps reduce arcing. Yes it may not prevent it with typical bonding methods but it should help reduce it. As far as grounding, lightning is one of the main reasons why we ground.

I agree that contact of an ungrounded conductor to a bonded and grounded object will likely cause an arc at the fault location. But consider if it is not bonded or grounded purposely. It will become energized and look for a path back to the source, possibly arcing at another location in its search back to the source. Arcing has not been eliminated either way. In the case of an intentional low impedance bond, the fault current will return to the source effectively causing timely operation of the OCPD thereby reducing the duration of arcing. In the case of no bond, the arc may persist and cause a fire.

I think that we can agree that for normal operation of equipment that is not intended to arc, bonding and grounding helps reduce arcing.

 

[mbrooke]

Ok, where in the code does it say to bond duct work?

 

[K8MHZ]

I think that we can agree that for normal operation of equipment that is not intended to arc, bonding and grounding helps reduce arcing.

Proof starts around 30 seconds in.

It's worth watching all the way through just to hear the last line. :lol:

 

[don_resqcapt19]

Ok, where in the code does it say to bond duct work?

250.104(B)...Informational Note No. 1: Bonding all piping and metal air ducts within the premises will provide additional safety.

 

[mbrooke]

250.104(B)...Informational Note No. 1: Bonding all piping and metal air ducts within the premises will provide additional safety.

Thanks But its not mandated nor is exact detail of such bonding spelled out.

 

[jaggedben]

Yes, it is exactly why bonding is required in many cases.

Okay, again I ask... seriously?

To my mind, the purpose of bonding is generally to cause arcing, under the theory that an overcurrent or other protective device will detect a problem and de-energize the circuit.

yes
in mining you can have 2 machines powered by a trailing cable
due to grounding/bonding Z differences each may have a different frame potential
if they touch current will flow and an arc may result
...

Interesting example, but relevant neither to the OP nor to why the NEC requires bonding. The NEC does not even cover mines.

...I agree that contact of an ungrounded conductor to a bonded and grounded object will likely cause an arc at the fault location. But consider if it is not bonded or grounded purposely. It will become energized and look for a path back to the source, possibly arcing at another location in its search back to the source. Arcing has not been eliminated either way. ...

Well put. (Emphasis added.)

I think that we can agree that for normal operation of equipment that is not intended to arc, bonding and grounding helps reduce arcing.

Except that what you said above states exactly the opposite?:huh:

Proof starts around 30 seconds in. ...

As far as I can tell this video is irrelevant to both the OP and the question of why the NEC or a residential insurance inspector would/should require bonding.

 

[MD84]

Okay, again I ask... seriously?

To my mind, the purpose of bonding is generally to cause arcing, under the theory that an overcurrent or other protective device will detect a problem and de-energize the circuit.



Interesting example, but relevant neither to the OP nor to why the NEC requires bonding. The NEC does not even cover mines.



Well put. (Emphasis added.)



Except that what you said above states exactly the opposite?:huh:



As far as I can tell this video is irrelevant to both the OP and the question of why the NEC or a residential insurance inspector would/should require bonding.

I would say that your tactic of editing my comments so that they make your point is poor etiquette. If you were to include the whole comment you would read that I have not contradicted myself. Bonding reduces arcing vs not bonding for a ground fault by reducing the duration the arc is allowed to persist. An object that is not bonded could arc indefinitely until starting a fire. An object that is bonded will arc for a very short time because the OCPD will trip on a ground fault.

This point you are trying to make is only relevant to ground faults. There are other reasons why bonding and grounding help reduce arcing. Do you dispute these as well?

 

[Ingenieur]

Okay, again I ask... seriously?

Interesting example, but relevant neither to the OP nor to why the NEC requires bonding...

exactly the reason
to keep devices equipotential

extreme
no bonding, broken wire/connection
100 A cb
480 fault to frame 277 to ground
no trip
1000 ohm individual touches frame
277 mA flows and he's dead

less extreme
poor bond 5 ohm
same fault 55 A flows
no trip 55<100
frame will have 277 on it with 277 dissapated across the gnd cond
touch = zap

we ground monitor all ckts to trip cb if >=2.7 ohm
We use a 15 ngr
frame under fault 2.7 x 15 = 40 vac to gnd
40 mA is survivable and close to let go
and v and i relays on the ngr which will trip and save him

if a conductor shorts to duct/pipe and is not bonded same scenario
the person becomes the ground path
if bonded the cb trips before contact

 

[kwired]

Okay, again I ask... seriously?

To my mind, the purpose of bonding is generally to cause arcing, under the theory that an overcurrent or other protective device will detect a problem and de-energize the circuit.

Arcing may be a side effect at times but creating arcing is not the reason for bonding. We bond things for 2 reasons.

1. To bring bonded items to equal potential.

2. To create low impedance paths for fault current to travel through should there be a fault, which ultimately we are bonded somewhere to the system grounded conductor and this allows high current to travel and cause quick opening of overcurrent protective devices.