Electrical Myths P2 - Grounding & Bonding

HVAC School - For Techs, By Techs

Bryan Orr

Training, Careers, Airconditioning, Self-improvement, Hvac, Business, Education, Refrigeration, Heating, Ac, Apprenticeship

4.8 • 985 Ratings

🗓️ 18 April 2017

⏱️ 35 minutes

🔗️ Recording | iTunes | RSS

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Summary

In this podcast episode, Bryan talks about grounding and some common misunderstandings related to ground, neutral, ground rods, and lightning.

The common phrase that "current goes to ground" is a myth. The transformer (or the power source) that feeds a building creates a potential difference in charges (voltage); current is the motion of electrons between a difference in charges.

A transformer has three terminals: two legs and the XO terminal (neutral). You have 240 volts between legs and 120 between each leg and the XO terminal. The leg of power going into the transformer is split into two in a single-phase application, so the sine waves are completely out of phase with each other. When you connect to a transformer, all of the power is either a balance between the two legs or is between the legs and the XO terminal (neutral); it NEVER goes to ground. If any power is traveling to "ground," it is traveling to the ground and going back to the source because there is no other path. Power travels to the ground and then to the source when neutral isn't properly bonded to ground.

Another common myth is that the current always takes the path of least resistance. The current does not always take the path of least resistance; it may take all appropriate paths.

All equipment is grounded to create a ground fault (this is called "grounding"). Then, it should be connected to a ground rod. Grounded assemblies attempt to dissipate high-voltage occurrences, such as lightning strikes and massive surges from distribution lines. Lightning is a very high-voltage DC phenomenon that can be fatal to people or equipment. So, dissipating electromagnetic pulses to ground is much safer.

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Transcript

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0:00.0	This episode of HVAC School and HVACR School.
0:08.1	is made possible by generous support from Testo and Carrier. The reason why Testo and Carrier are
0:16.4	sponsors of this podcast and support what we do is because I believe in what
0:21.1	they do and they are showing that they care about technicians by
0:24.4	investing in something that is essentially technical training that's what
0:27.7	HVAC school and HVAC school.com is. So thank you to them for continuing to create good quality products.
0:35.0	Also want to mention TrueTech Tools.
0:37.0	If you go to TrueTech Tools.
0:39.0	And use the offer code Get Schooled, you'll get 8% off of your purchase of high quality tools. And I also want to mention
0:45.9	HVAC HACs. HVAC-HACs. HVAC-HACs. Reminds you, don't be a hack. This is the guy who once had to have a bank evacuated
0:58.0	because he tested the heat strips during a maintenance.
1:02.0	Brian all.
1:03.4	Hey hey everybody, this is Brian.
1:05.2	And I promised you that this would be a two-part series,
1:08.2	two-part series on electrical considerations,
1:11.6	electrical myths, I guess, is what I said.
1:14.6	And I am not going to back down on that promise.
1:17.8	When I make a promise to you, listener to HVAC school, we'll call you Bob.
1:23.0	Let's say your name is Bob.
1:24.1	Maybe your name is Bob, maybe it isn't.
1:26.0	But Bob, when I make a commitment to you, I keep my promise.
1:29.2	And today we're gonna talk about grounding and bonding.
	...

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