# #electricity

### Tech Tips:

Parallel Circuit Resistance
By:Bryan OrrIn a series circuit (loads connected in a row end to end), it's easy to calculate total circuit resistance because you simply add up all the resistances to get the total. In a parallel circuit, the voltage is the same across all the loads; the amperage is simply added up, but the resistance is […]
Ohms/Continuity Basics
By:Bryan Orr Some quick basics – An ohmmeter is used to measure the resistance to electrical flow between two points. The ohmmeter is most commonly used to check continuity. Continuity is not a “measurement” as much as it is a yes/no statement. To say there is continuity is to say that there is a good […]
What’s the Difference Between 208v and 240v?
By:Bryan Orr The easy answer is 32v. Class dismissed. I’m only joking, of course. Finding the difference between 208 and 240v power supplies may sound quite simple, but there are some pretty sharp fundamental differences. Apart from the obvious differences in overall voltage, 208 and 240v power supplies use the electrical company’s power differently. The […]
3-Phase Motors—The Basics
By:Bryan Orr Fundamentally, three-phase, alternating current motors are about as simple as a motor gets. The power company produces three phases by spinning magnets. Then, on the other end, we produce electromagnets that spin the motor according to the same 60 cycles per second frequency (60hz). All three phases are 120 degrees out of phase […]
Using Power Factor to Check Capacitors Under Load
Capacitors are traditionally tested with a capacitance meter (commonly found as a function within a multimeter), with the component taken entirely out of the circuit. “Bench testing,” as this method is referred to, is hands-down the safest method of checking capacitance in microfarads. All other methods require the capacitor to be wired into the circuit […]
Using Power Factor to Check Capacitors Under Load
Capacitors are traditionally tested with a capacitance meter (commonly found as a function within a multimeter), with the component taken entirely out of the circuit. “Bench testing,” as this method is referred to, is hands-down the safest method of checking capacitance in microfarads. All other methods require the capacitor to be wired into the circuit […]
Isolation Diagnosis
There are many great diagnostic tools available to the service technician today, but I haven't found a tool as versatile as the simple isolation diagnosis. There are many ways this concept can be applied, but let's start with some examples so that you get what I mean. Low Voltage Short Circuit Isolation Diagnosis You arrive […]
Something You May Want to Consider on Every Call
There are a few important things that I suggest checking on every service call to reduce callbacks and increase customer satisfaction. One of them that often gets missed is preventing wire rub-outs. One of my area managers and experienced tech Jesse Claerbout shot a video showing the simple step he takes to prevent major damage. […]

### Videos:

Don’t Overfill Refrigerant Recovery Cylinders The Easy Way
In this video we review the HVAC School app tank fill calculator and how to use it to prevent the overfilling of refrigerant recovery cylinders.
Something You May Want to Consider on Every Call
There are a few important things that I suggest checking on every service call to reduce callbacks and increase customer satisfaction. One of them that often gets missed is preventing wire rub outs. One of my area managers and experienced tech Jesse Claerbout shot a video showing the simple step he takes to prevent major […]

### Podcasts:

Basic Electrical Theory
By:Bryan Orr In this episode of HVAC School, Bryan talks to his sons about basic electrical theory. Electrical theory normally requires trigonometry, calculus, and all of those fun maths. However, the basics are so easy that a 12 and 14-year old can figure it out. Electrical theory follows many of the same principles as thermodynamics—however, […]