Sunday, February 14, 2010

One thing CFLs can save you from: electrical fires

My earlier post arguing the "hidden defects" of compact fluorescent lamps omitted one important advantage, brought up to me by my friend Gene Szafranski. The lower current drawn by CFLs versus incandescent bulbs for a same amount of light is very important in buildings with old wiring.

Old wiring with the coiled metal sheath on the outside is known to be a very serious fire hazard. This type of wiring is common in most homes that built before the second World War. The conductor wires inside the metal sheath are themselves wrapped in individual insulators which used to be fabric and early plastics (nowadays, our plastic insulators are far better quality). As these old insulating materials aged, they became brittle; if you've replaced a ceiling fixture on an older home, you are likely to have seen bare wires, stripped of their insulation. There are two reasons for this brittleness.

First, the simple heat of the lightbulb serves to bake the wire; that's why many lamps have stickers restricting their use to 60W bulbs or less - a limit that we often ignore as we grow accustomed to more light. Second, the current drawn through the wire to power the lightbulb creates a proportional amount of heat. So long as the insulator is in good shape, that's not a problem. But once the insulation begins to decay, the stripped wire may arc with the external sheath. If the ground connection is improper (often the case), this arcing can lead to the exterior metal coil becoming red hot, which in turn risks setting ablaze any material with which it comes into contact.

This is definitely one positive thing to be stated in favor of CFLs. On the other hand, using CFLs will not ensure that a house with old wiring does not catch fire. While retrofitting electrical systems is very costly, it is probably one of the very safest investments in an old home.

Consume less, share, repair - and smile!
4 simple steps towards sustainable living...

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