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24 Acronyms DIYers Need to Know

Acronyms, you know what they are but do you know what they mean? Learn the DIY acronyms you need to know and impress some people along the way.


GFCI is an important acronym to know when doing electrical work. It stands for ground fault circuit interrupter. What it does is shut off a circuit when it detects current is flowing through an unintended path. A GFCI plug receptacle will reduce the danger of deadly shock from faulty plug-in cords.

See how to install a GFCI outlet and how to test a GFCI outlet.


British thermal unit is a measuring tool of temperature. It is defined as the amount of heat needed to raise the temperature of one pound of water by one degree Fahrenheit. Why is Btu important? Because the number of Btus needed for your home corresponds to the square footage you’re trying to heat and cool. The larger your home, the more Btus you want. Find out if it’s time for a new furnace or how to cut down on heating costs.


Medium-density fiberboard or MDF is an inexpensive option for woodworking and carpentry projects. MDF is basically sawdust and glue fused together under pressure. It works well for shelving and storage projects because it cuts well.

Try using MDF for a flooring project.


National Electrical Code or NEC is the Bible for electrical work around the house and will help guide safe installation of electrical wiring. Consult the NEC before doing any electrical work.

Find out how to run power anywhere in the home.


Polyvinyl chloride is the actual name of one of the most versatile items in any shop, PVC piping. PVC was first synthesized in 1872 by a German chemist. Later Waldo Semon and B.F. Goodrich later made it more flexible and its use expanded. Just don’t get it confused with ABS pipe.


The positive crankcase ventilation valve in your vehicle is a one-way valve that recycles the crankcase gases back to the engine to burn. If you have a plugged PCV valve, you’ll notice a rough idle and poor mileage. It can also create oil leaks.

See why checking your PCV valve is the world’s easiest diagnostic test.


You see it on light bulbs and plenty of other items but what’s that UL stand for? It stands for Underwriters Laboratories based out of Northbrook, Illinois. UL certifies, validates, tests, inspects, audits, advises and educates and has done so since 1894.

Find out why you should check to see if that UL label is on a home security system and why it’s especially important to see on a surge protector.


You know it as the cure-all for all things immoveable or getting rid of pests. But do you know what the acronym means? The WD part means water displacement and 40 comes from the number of attempts it took to get the formula worked out back in 1953.

Make sure you always keep a can of WD-40 within reach.

David Spates/Shutterstock


The shorthand has overtaken the longer version of heating, ventilation and air conditioning and for good reason, that’s a mouthful.

Check these things before calling an HVAC technician to avoid looking foolish and figure out just which kind of furnace filter is the best.


Wi-Fi isn’t necessarily an acronym but it is an abbreviation of sorts. Technically, it stands for wireless fidelity and the name intended to be a play upon hi-fi or high fidelity. The Wi-Fi Alliance, which holds the Wi-Fi trademark, has referred to Wi-Fi as standing for wireless fidelity in the past.

Fix the slow Wi-Fi spots at home or see how a Wi-Fi garage door opener can open new possibilities.


PEX takes its name because it is a form of polyethylene with cross-links, hence the X in PEX. The plumbing material has become en vogue because it doesn’t require glue and it’s less likely to burst if it freezes.

Find out how to plumb with it.



GPF stands for gallons per flush, which means how much water you’re using and how it will flush. When toilets started going to 1.6 gallons per flush it meant a lighter flush but that problem has since been solved.

Find out how to get the toilet you’ll love and learn how to save on water in the bathroom. 

Plus: How to Unclog a Toilet

Photo: Courtesy of Harbor Freight


PSI or pounds per square inch measure measures things like tire pressure and water pressure.

Determine exactly how much psi you really need for a compressor or in a pressure washer.

EMT Conduit

Electrical metallic tubing (EMT) is a great choice for electrical work because it’s strong and cheap. Check out how easy EMT conduit is to use and see how to install surface-mounted wiring and conduit.


An oldie but a goodie, keep it simple, stupid. Sometimes overthinking something does more harm than good, so remember to keep it simple to save yourself some stress.

Make roofing a house easy and house cleaning simpler.


Someone who knows their way around a car is certainly familiar with SAE or Society of Automotive Engineers. SAE tools are the ones that are measured in fractions of inches. SAE will also be found on oil and horsepower ratings.

Pick out the best socket set for your shop and see how you should store tools.


Yes AC/DC is one of the greatest rock bands to ever play but it also stands for alternating current and direct current. Alternating current changes direction periodically while direct current moves in a straight line. Most electronics use direct current. AC delivers power to houses and office buildings because it travels over distances better.

See why charging a laptop on a car cigarette lighter needs an inverter or turn your truck into a generator.


NPT or National Pipe Thread, is a U.S. standard for tapered threads on threaded pipes and fittings. NPT goes back to 1864 when William Sellers created a standard for nuts, bolts and screws.

Solve some plumbing problems by learning how to join dissimilar pipes or why you would wrap threaded pipes.


TPI stands for teeth per inch and no, that’s not how they measure a shark’s danger level. Teeth per inch indicate types of saw blades. Higher TPI blades leave a smoother surface but cut slower than lower TPI blades. Check out some essential bandsaw tips for your next project.


ASTM (formerly American Society for Testing and Materials, now ASTM International) is making sure every day items are safe for use—from toys to aircraft by developing standards through its base of volunteers. It has committees on 3D printing and nanotechnology.


UF or underground feeder cable runs electricity wires under ground that are in cased in plastic. UF is a type of NM cable.

NM cable

Non-metallic cable (NM) is flexible electrical cable with a plastic covering. It’s cheap and easy to work with and safe.


An arc fault circuit interrupter (AFCI) is located in the main electrical panel or a subpanel in a home. It can be reset like a standard circuit breaker.


The American Society of Mechanical Engineers sets standards for ratchet strength so it’s a good organization to familiarize yourself with for the future.

Understand the difference between six-point sockets and 12-point sockets.