Wayne, That is not exactly true. An outlet rated at 15 amperes cannot have any load greater than 12 amperes plugged into it. An outlet rated at 20 amperes cannot have any load greater than 16 amperes plugged into it. This is clearly stated in Article 210.21(B)(2) of the National Electrical Code. A device that actually draws 20 amperes at 120 VAC must be plugged into an outlet and branch circuit rated at 30 amperes.
When load currents exceed 16 amperes at 120 VAC, it's time to consider a branch circuit rated at 208 or 240 VAC. Most repeaters and high-power PAs have optional connections to enable operation on 208 or 240 VAC. Keep in mind that there is no such voltage as "220" although that obsolete figure is still in common usage. The nominal single-phase voltage supplied to residences is 120/240 VAC, while the electrical supply to light commercial, apartment complexes, and condos is usually 120/208 VAC derived from two phases of a three-phase distribution system. I mention this because a fellow Ham who now lives in a large apartment complex mentioned to me that his 500 watt rig that worked fine in his former home was not putting out full power at his new location. The cause was revealed when he measured his line-to-line voltage as close to 208 VAC. His power amplifier was rated for 240 VAC, but was "starving" when fed 87% of its design voltage. A commercially-available "boost" transformer was installed to give him a true 240 VAC supply. Problem solved. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Wayne Sent: Thursday, July 17, 2008 11:01 AM To: [email protected] Subject: Re: [Repeater-Builder] Re: RadioShack Recalls Power Supplies To properly plug in an item that is a 20 amp draw. etc., one should install a 20 amp outlet. This can be single or duplex, and is readily spotted (if dual purpose) by the fact that one side will be flat instead of vertical, or have both horizontal and vertical on that side. the flat/horizontal is on the neutral side. Not to be confused with a similar looking outlet for 250 volts, which has two flats , and one has vertical as well on the left side, looking at the front with the ground hole down. Anyway, there are oulets made for 20 or more amps, which are different than the 15 amp common outlets. local ordinances can often be more stringent than even the NEC codes. of course, if you are running a high power repeater, you would probably wish to put it on a circuit breaker by itself. But ordinary house wiring normally has several outlets wired in series from one breaker, and is NEC approved that way. Shop and Industrial become another matter, ha ha ha... Wayne WA2YNE On Sun, 06 Jul 2008 20:08:33 -0500, Bruce Bagwell <[EMAIL PROTECTED]> wrote: > I figured that was A local code, not NEC. The only reason I can think > of for that requirement is the ampacity of the 12 or 14 ga wires. While > we all know, in actual use, 2 or more outlets strung along will not all > have 15 amp or higher loads in EACH outlet. However, theoretically, each > outlet could have A 20 amp load plugged into it.That is probably why > some pencil pusher decided each outlet needs its own wire. (Never mind > the fact the breaker would trip regardless of what is plugged into each > outlet or the number of wires leading to said outlets, but that's > another crazy thread) As for the Breaker Box, I would assume each also > has its own breaker. Trying to stuff more than one wire into A breaker > would more fun than I care to have. > > Bruce > KE5TPN > -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/ ------------------------------------ Yahoo! Groups Links
