Monday, January 14, 2019

DOMESTIC TECHNOLOGY: Not Rocket Science, But Still A Mystery To Some

Electricity was leaking all over the house.
(With appreciation to James Thurber).
Almost eighty years ago, the humorist James Thurber wrote about an aunt of his who had some profound misconceptions about technology. She was convinced, among other things, that electricity leaked out of empty light sockets. Today we like to think we’re pretty savvy about such things, but judging by some of the questions I get from clients regarding their houses, I suspect we all still have a bit of Thurber’s aunt in us:  

•  If I turn the thermostat way up, will my house heat up faster? Alas, no. The typical thermostat is more like an on/off switch than an accelerator; it’s activated by a bimetallic spring that responds to changes in temperature. Since it can’t do any more than turn the furnace on or off, setting the thermostat to 90° won’t heat the house any faster. However, if your furnace has a variable-speed blower (not all do), it may push the warm air a little faster than normal.

Yes, even the fanciest new thermostat
is still basically just an on/off switch.
• My refrigerator is supposed to cool things, so why is there warm air coming from the back? A refrigerator works by compressing a special gas called refrigerant. The gas gets hotter when it’s compressed, just as the air in a bicycle pump gets hotter. That heat is dissipated into your kitchen by a fan coil, which is where the warm air comes from. But here’s the neat part of the process: when the compressed gas is allowed to expand again, it tries to regain the lost heat by absorbing it from other objects—in this case, the warm six-pack you just put in the fridge. 

A refrigerator works by transferring heat from the inside
to the outside—where these radiator-like coils dissipate it
into your kitchen (most newer refrigerators have the coils
underneath, however).
•  Fuse, circuit breaker, GFCI, AFCI—what’s the difference? A fuse is a device meant to prevent too much current from flowing through a wire of given size, because when that happens the wire gets hot and, as Jesse Jackson might say, hot wires start fires. Fuses are found in most houses predating World War II; they consist of a screw-in socket enclosing a thin strip of metal.  When the metal carries more current than the rating of the fuse, the metal strip melts (or “blows”) and the circuit is broken.  

A ground fault circuit interruptor
may not look like much, but
it can save your life.
The problem with fuses has always been their multifarious ratings—10 amp, 15 amp, and so on. When one blew, no one ever seemed to have the right replacement on hand. So they’d cheat by grabbing a fuse with a higher rating (or worse yet, a copper penny), occasionally burning down the house as a result.

The inconvenience and frequent misuse of fuses brought us the circuit breaker. It’s essentially a switch that serves the same purpose as a fuse, except that when it “blows”, you simply reset it—hopefully after correcting the condition that made it trip. 

GFCIs, or Ground Fault Circuit Interrupters, are amazing little electronic devices that might save your life someday. Suppose you decide that, in order to save time, you’re going to blow-dry your hair while you’re still in the tub. Oops!  You dropped the hair dryer in the suds!  Fortunately, the GFI-protected receptacle you wisely installed in your bathroom senses that 120 volts is about to take a little road trip through your body, and within milliseconds, it shuts of the current. Relatively cheap (especially compared to being dead) and amazingly effective, GFI protection is now required by code for any receptacle within 6’  of sinks, lavatories or other water sources, as well as in garages and at outdoor receptacles. 

Arcs from frayed lamp cords can and do cause lots of fires,
which is why building codes now require AFCI-
protected outlets in bedroom.
AFCIs, or Arc Fault Circuit Interrupters, are similar devices that are now required by code in all sleeping rooms. Unlike GFCIs, they are designed to detect arcs such as those caused by, say, a frayed lamp cord—one of the leading causes of home electrical fires. They are only required in sleeping rooms because, presumably, the occupants of other rooms are awake and are more likely to detect an incipient fire.

•  And by the way, although electricity doesn’t leak out of an empty light socket, you can still fry yourself if you stick your finger in one—so keep a bulb in it for safety’s sake.

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