meta_pixel
Tapesearch Logo
Log in
HVAC School - For Techs, By Techs

Short 14 - The Voltage Drop Tool

HVAC School - For Techs, By Techs

Bryan Orr

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

4.8985 Ratings

🗓️ 17 July 2018

⏱️ 12 minutes

🧾️ Download transcript

Summary

In today's short podcast episode, Bryan discusses the voltage drop measurement tool, also commonly known as the voltmeter. You can also find this voltage drop tool on multimeters. You use them to check voltage drops, NOT the actual voltage.

We get voltage values from a potential difference. So, we check for these differences via voltage drops. For example, you can determine if contactor pitting or carbon buildup is problematic by measuring the voltage across contact points. Your meter will read the voltage drop.

We don't often deal with intentional series circuits. However, we can see unintentional series circuits when switchgear or wiring adds more resistance than it should. The voltage drops when that happens. You can also use a voltmeter to locate an open circuit; when you no longer see voltage as you walk through a circuit, you can determine that you have found an opening.

An HVAC system with low current may have a cumulative voltage drop, which is the total drop of all the voltages in the system, including the crankcase heater and compressor windings. Kirchoff's second law helps explain the behavior of the voltage in a system; the law states that for a closed-loop series path, the algebraic sum of all voltages around any closed loop is equal to zero.

Any time you use a voltmeter, your two leads communicate the voltage drop from one lead to the other, whether those are across contactors or different points on the same wire. When finding an undesigned voltmeter is most effective when used under load. You will see a massive voltage drop when you use a voltmeter under load; otherwise, you will see a much smaller voltage drop.

Check out Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Transcript

Click on a timestamp to play from that location

0:00.0

This is the 14th installment of the short episodes where we just talk about a single topic,

0:08.0

single technical topic and today we're talking about the voltage drop measurement tool. And before we do that, I want to mention our excellent sponsors.

0:15.2

Carrier, carrier.com, Mitsubishi Electric cooling and heating,

0:19.5

the UEEI Hub smart kit with their high quality induct thermohogrometers as well as

0:25.3

temperature clamps and refrigerant probes all in one nice kit if you look at the

0:29.8

Hub 6 the WRS Connected Scales from UEI, those are the scales that I prefer.

0:35.8

Refrigeration Technologies at refriggedec.com, some of the best made American chemicals

0:40.7

for the HVAC industry.

0:42.1

Check out refrigeration Technologies at refrigitech.com.

0:44.8

Air Oasis, makers of the bipolar and nano air purifiers,

0:48.1

the air purification products that we use at Kalo services.

0:52.4

And then finally, BisPallorg if you're looking for a

0:54.9

technician then talk to Patrick over at bizpal.org and see if he can help you

0:59.1

find your next technician for your company all right right, here we go. So a voltage drop tool.

1:04.3

It's just a volt meter people, it's just a volt meter. The way that I'm teaching

1:08.2

volt meters now and how they're used is to use it to check for a voltage drop.

1:13.0

And that seems really counterintuitive

1:15.0

because what do most people do with a voltmeter.

1:17.0

They're checking across the line.

1:18.0

So they check L1 to L2.

1:20.0

Well, there's no voltage drop, they think, to themselves.

1:23.4

But in fact, every time that you are measuring voltage,

...

Please login to see the full transcript.

Disclaimer: The podcast and artwork embedded on this page are from Bryan Orr, and are the property of its owner and not affiliated with or endorsed by Tapesearch.

Generated transcripts are the property of Bryan Orr and are distributed freely under the Fair Use doctrine. Transcripts generated by Tapesearch are not guaranteed to be accurate.

Copyright © Tapesearch 2025.