Home / Electricity for the Non-electrical
If you have an electrical education, don’t read this, it will drive you nuts.
These descriptions are intended to create concept, not every nuance of technical detail.
If more detail is wanted, Wikipedia.com is a good initial source.

Electricity – The transfer of electrons from one point to another, in this context, usually along a metallic wire. Yes, these are the same electrons that are found in atoms!

Direct Current electricity (DC) – The electricity (electrons) flows on the wire in one direction from the negative end to the positive end. Electricity from a battery is an example of DC.

Alternating Current electricity (AC) – The electricity (electrons) reverse direction on the wire multiple times per second. In North America, utility power does a complete backward and forward cycle 60 times a second; in most other places it is 50 times a second.

Volts (V) measure the potential difference between 2 points. Like water pressure in a pipe tells how far water will squirt, volts indicate how far a spark will jump.

Amperes (A) measure how much electricity (moveable electrons) is present. Is it a puddle or a pond? (But without the squirt factor!)

Watts (W) measure how much power the electricity delivers. Watts are the Volts times the Amperes. In other words, how much electricity (amperes) there is, and how far will it squirt (volts), combined.

Hertz (Hz) is the same as cycles-per-second. In alternating current electricity (AC), it is the number of times per second the electrons do a complete backward and forward cycle.

Phase (ph or Ø) –
1. Split phase (residential) - The electric company typically delivers 240 volts AC to residences. At the circuit breaker box, this 240 volts is split into 2 halves which are called “phases.” The first half, the first 120V, commonly called “X”, is routed through multiple circuit breakers to outlets and lights. The second half, the second 120V, called “Y”, is sent through more circuit breakers to more outlets and lights. “X” and “Y” circuits and their outlets are randomly mixed in the residence, depending on how the electrician laid out the wiring. For 120 volt uses and outlets, users aren’t aware of phases and it makes no difference. Your electric company calls this “split phase service.” (Some people call it 2 phase service due to the 2 phases one obtains after the splitting.)
2. 3 phase (commercial and industrial) - In its most common form, there are three sources of 120 volts for common outlets and 208 volts for larger appliances. Quick 220® Systems will deliver 208 volts when plugged into two different phases of a 3 phase electrical system. For more detail on 3 phase systems and other electrical options supplied in the commercial/industrial setting, Wikipedia.com is a good initial source.

Ground Fault (Circuit) Interrupter (GFI or GFCI) – The GFCI protects against electrical shock due to electrical leakage around faulty insulation when one contacts water, a moist surface, or a grounded metallic object. GFCI’s are commonly found in kitchens, bathrooms, outside locations, garages, and similar locations. The GFCI is commonly located in an outlet, recognizable by the small “TEST” and “RESET” buttons. Outlet GFCI’s will protect the outlet they are part of and usually every outlet after that one in the circuit. In newer circuit breaker panels, the GFCI may be part of the circuit breaker with “GFCI” in the print next to the circuit breaker switch lever and having a “Test” button next to the breaker switch lever.

Arc Fault Circuit Interrupter (AFCI) – In recent years, building codes have started to require AFCI’s, especially in bedroom areas. The AFCI detects sparking in electrical circuits which can lead to fires. The AFCI looks much like a GFCI. When part of an outlet there is a “Test” and “Reset” button on the device. It may also be located in the circuit breaker panel where the breaker will have the letters “AFCI” printed next to the switch lever for the protected circuit.

NEMA (National Electrical Manufacturer’s Association) – NEMA developed a plug and receptacle (outlet) standard to make these items interchangeable between different manufactures of North American electrical hardware. For example, the standard 3 prong, 120 volt plug is NEMA 5-15P. Use this chart to break down the codes: for example, NEMA 5-15P or NEMA 6-20R

1st Number Max. Volts Wires
5 125 Hot, Neutral, Ground
6 250 Hot, Hot, Ground
10 250 Hot, Hot, Neutral
14 250 Hot, Hot, Neutral, Ground
Number after dash is maximum amperes.
“P” is a plug; “R” is a receptacle (outlet).
“L” is a locking plug or receptacle; example (L6-20P). Locking plugs and outlets won’t fit non-locking devices.

UL (Underwriters Laboratories), CSA (Canadian Standards Association), OSHA (United States Department of Labor, Occupational Safety and Health Administration), Intertek (a Nationally Recognized Testing Laboratory) - UL, CSA, OSHA, and the Nationally Recognized Testing Laboratories address the safety of products that are brought into the home or business. The NEC (National Electrical Code) addresses the permanent wiring of buildings and other facilities. In general, if it is in the walls or a permanent part of the facility, NEC defines how to do it safely. If you can plug it in, then UL, CSA, OSHA, and the testing laboratories handle product safety.