Uploaded August 2026 | Updated September 2026, 51 minutes ago
Why can two multimeters measure the same circuit and give you different readings? In this video, electrician Dustin Stelzer explains True RMS, how a multimeter measures AC voltage, and why the right digital multimeter matters for accurate electrical troubleshooting.
Using the Fluke 106 and Fluke 117, Dustin walks through the difference between measuring a clean sine wave and measuring a distorted, non-sinusoidal waveform. You’ll see why 120V AC has a peak near 170V, how RMS represents the effective heating value of AC compared with DC, and why waveform distortion can change the reading you see on your meter.
The video also covers peak-to-RMS calculations, diode rectification, harmonic distortion, and examples of loads where True RMS becomes especially useful, including dimmers, welders, electronic ballasts, computer power supplies, and UPS outputs. ⚡
Thanks to @Flukecorp for sponsoring this video. The Fluke 106 is a compact digital multimeter intended for everyday applications where True-RMS accuracy is not required, while the Fluke 117 adds True-RMS capability for accurate measurements on nonlinear loads.
If you’re looking to buy either meter or add to your electrician tools, use discount code ElectricianU12 at fluke.com
Whether you’re an apprentice learning electricity and electrical theory, taking electrician courses, or an experienced electrician troubleshooting residential or commercial electrical systems, understanding what your multimeter is actually telling you matters.
00:00 - Intro
00:19 - Meter Comparison
00:41 - Why RMS Exists
01:42 - Changing AC Voltage
03:17 - RMS Math
05:03 - True RMS
06:31 - Diode Rectification
09:18 - Peak vs RMS
11:50 - Why 120 Volts
13:55 - Harmonic Distortion
15:18 - Effective Voltage
🤘⚡️EU Learning System⚡️🤘
For Individuals --- electricianu.com/learning-system-for-individuals
For Businesses --- electricianu.com/learning-system-for-businesses
-Video courses on every side of the electrical trade (theory, code, safety, wiring, install, troubleshooting, leadership, and more)
-Practice exams for 2017, 2020, 2023 code
-YouTube videos categorized and searchable
-Audio lessons
-Forum
-Business version has admin portal and ability to assign learning to technicians and monitor progress
-Any business size from 2 techs to 2,000!
🎓💡CONTINUING EDUCATION💡🎓
Sign up here --- electricianu.com/electrician-continuing-education-online-electrician-u
-State Approved
-Video Based
✍📝PRACTICE EXAMS📝✍
Get them here --- electricianu.com/electrician-exam-practice-tests
-2017, 2020, and 2023 NEC versions
-Online Residential Wireman Exam
-Online Journeyman Exam
-Online Master Exam
-300 Question Online Code Cannon (not license specific, all code)
-Take as many times as you want
-All of the above come with printable PDFs
🎤🎧PODCAST🎧🎤
Spotify:
open.spotify.com/show/7ldCwdxhWnT0R3nne96XjC?si=a42a98b83c3549fc&nd=1
Apple Podcast:
podcasts.apple.com/us/podcast/electrician-u/id1583270265
📱👍SOCIALS👍📱
TikTok - tiktok.com/@electricianu
Instagram - instagram.com/electrician_u
Facebook - facebook.com/TheElectricianU
Reddit - reddit.com/r/ElectricianU
Rumble - rumble.com/c/ElectricianU
Discord - discord.gg/electricianu
🎧🎹Music, Editing, and Videography by Drake Descant and Rob LeBlanc🎹🎧
#electrician #electrical #electricity
Why can two multimeters measure the same circuit and give you different readings? In this video, electrician Dustin Stelzer explains True RMS, how a multimeter measures AC voltage, and why the right digital multimeter matters for accurate electrical troubleshooting.
Using the Fluke 106 and Fluke 117, Dustin walks through the difference between measuring a clean sine wave and measuring a distorted, non-sinusoidal waveform. You’ll see why 120V AC has a peak near 170V, how RMS represents the effective heating value of AC compared with DC, and why waveform distortion can change the reading you see on your meter.
The video also covers peak-to-RMS calculations, diode rectification, harmonic distortion, and examples of loads where True RMS becomes especially useful, including dimmers, welders, electronic ballasts, computer power supplies, and UPS outputs. ⚡
Thanks to @Flukecorp for sponsoring this video. The Fluke 106 is a compact digital multimeter intended for everyday applications where True-RMS accuracy is not required, while the Fluke 117 adds True-RMS capability for accurate measurements on nonlinear loads.
If you’re looking to buy either meter or add to your electrician tools, use discount code ElectricianU12 at fluke.com
Whether you’re an apprentice learning electricity and electrical theory, taking electrician courses, or an experienced electrician troubleshooting residential or commercial electrical systems, understanding what your multimeter is actually telling you matters.
00:00 - Intro
00:19 - Meter Comparison
00:41 - Why RMS Exists
01:42 - Changing AC Voltage
03:17 - RMS Math
05:03 - True RMS
06:31 - Diode Rectification
09:18 - Peak vs RMS
11:50 - Why 120 Volts
13:55 - Harmonic Distortion
15:18 - Effective Voltage
🤘⚡️EU Learning System⚡️🤘
For Individuals --- electricianu.com/learning-system-for-individuals
For Businesses --- electricianu.com/learning-system-for-businesses
-Video courses on every side of the electrical trade (theory, code, safety, wiring, install, troubleshooting, leadership, and more)
-Practice exams for 2017, 2020, 2023 code
-YouTube videos categorized and searchable
-Audio lessons
-Forum
-Business version has admin portal and ability to assign learning to technicians and monitor progress
-Any business size from 2 techs to 2,000!
🎓💡CONTINUING EDUCATION💡🎓
Sign up here --- electricianu.com/electrician-continuing-education-online-electrician-u
-State Approved
-Video Based
✍📝PRACTICE EXAMS📝✍
Get them here --- electricianu.com/electrician-exam-practice-tests
-2017, 2020, and 2023 NEC versions
-Online Residential Wireman Exam
-Online Journeyman Exam
-Online Master Exam
-300 Question Online Code Cannon (not license specific, all code)
-Take as many times as you want
-All of the above come with printable PDFs
🎤🎧PODCAST🎧🎤
Spotify:
open.spotify.com/show/7ldCwdxhWnT0R3nne96XjC?si=a42a98b83c3549fc&nd=1
Apple Podcast:
podcasts.apple.com/us/podcast/electrician-u/id1583270265
📱👍SOCIALS👍📱
TikTok - tiktok.com/@electricianu
Instagram - instagram.com/electrician_u
Facebook - facebook.com/TheElectricianU
Reddit - reddit.com/r/ElectricianU
Rumble - rumble.com/c/ElectricianU
Discord - discord.gg/electricianu
🎧🎹Music, Editing, and Videography by Drake Descant and Rob LeBlanc🎹🎧
#electrician #electrical #electricity
