Electrical Power
Dear Gary: I will be building a new home later this year and wish to get the cabling work installed at the construction stage, which won’t be a problem. One of the concerns I have is that over the years I have read articles which say you should install a dedicated power line from your meter box to your A/V room which has a load of 20 amperes. I do understand the benefit for having the line separate from the rest of the electrical circuits in the house, but when I have quizzed some electricians on this subject they say 20 amperes is way too much. The electricians suggest that such a line is a waste and not to install one that is rated so high. What gives? Could you please explain what the benefit of a 20 ampere line is over a lessor line, say 10 Amperes? Also, is it advisable to run all the A/V equipment off this one line? Or should multiple power-lines be installed for each component or a group of components—first power amps, then sources and so on? Many thanks and keep up the excellent work on WSR.
John Barsby, Sydney, Australia
Audio Review Editor Richard Hardesty Comments:
Ohm’s law for power states that P=IE where P is power in watts, I is current in amperes and E is RMS voltage. In the United States we have 110/120 volt power and 20 amp circuits are the norm (in recent construction). 20 times 110 equals 2,200 watts of total power. A 220 volt, 10 amp circuit can deliver the same power. 220 times 10 equals 2,200 watts. nn
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