Flawed video on grounding (4 min)

Saturn_Europa

Senior Member
Location
Raleigh, NC USA
Please point out some errors for me to forward on. Its an international aid agency not a electrical company so I wasnt surprised. Please keep it respectful.

I didnt produce the video.

Most systems Ive seen in the field are TNC-S or TNS.

 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
His initial comment that grounding systems in combination with RCDs (residual current devices aka GFIs) protect the user in T-T systems are OK. But he doesn't point out that the grounding system on a T-T (which has no bond from ground conductor to neutral) only provides an adequate path for fault currents to trip an RCD but not for regular circuit breakers. In fact he implies that the path through the ground rod provides a good path for high fault currents which it clearly does not. He does show a 30mA RCD at 2:38 that's upstream of other breakers but he doesn't even say anything about it.
 

DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
Please point out some errors for me to forward on. Its an international aid agency not a electrical company so I wasnt surprised. Please keep it respectful.

I didnt produce the video.

Most systems Ive seen in the field are TNC-S or TNS.

He starts out right away with a falsehood: "the grounding or earthing system creates a safe path for the current to flow into the ground if the phase or neutral wire touches the casing of electrical equipment." The author of this video clearly doesn't understand electrical theory.

Fault current goes through the EGC where it is bonded to the neutral service entrance wire at the main disconnect and then travels on the neutral back to the transformer where the current originated. Some current goes through the earth but probably 99.999% of it through the neutral wire. The transformers neutral is also bonded at the pad or pole. So the ground IS a path but not enough conductivity to facilitate the opening of an OCPD. Without the neutral, all the fault current would travel via the EGC, then the GEC, through the electrodes and then the ground and to the transformers ground and then finally to the transformer. The current flow would almost certainly be insufficient to trip a breaker.

Sent from my BE2028 using Tapatalk
 

mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
What others have said. Basically its fundamentally flawed in the concepts. Grounding and Bonding 101.

Current seeks the source NOT the ground. The only reason some current may go into ground is because the utility transformer is also common to it. If the utility was isolated from ground no current flow to ground.

He stated if a neutral touched the case of equipment it could shock people. FALSE, so long as good continuity is maintained a neutral touching the case of an appliance is the same as the EGC.

The video does not differentiate between the EGC and the GEC. It illustrates them as one and the same. They are different and serve different functions.

Ground rods are NOT copper. They are steel with copper clad.

Grounding and bonding are not complex they are just frequently misunderstood because people lack comprehensive electrical fundamentals.
 
Top