At 06:15 AM 06/11/10, you wrote: >On 6/10/2010 8:03 PM, Eric Lemmon wrote: > > A Gas Tube Arrestor is better suited to telephone lines and RF coaxial > > cables than to 120 VAC AC power lines. If used on AC power lines, when > > fired, they will produce a "bolted short" and cause a great deal of current > > to flow. This is not a good thing! > > > > Some computer accessory suppliers vigorously market surge arrestors as a > > must-have accessory, and the American public is being > brainwashed. In fact, > > most computer circuits do not benefit from surge arrestors, and some power > > strips that include surge arrestors are banned by many large companies as > > being prone to catch fire. The gray plastic, half-moon-shaped power strip > > made by APC is known to be a fire hazard, and my employer (Boeing) banned > > them after the second fire incident. In each incident, the MOV > > spontaneously overheated and melted the plastic case, which then caught > > fire. Fortunately, the damage was limited to the wooden shelf it was > > sitting on in one case, and some scorched carpet in the other. As a result > > of these two incidents, the CPSC recommended that any power strip > be made of > > metal rather than plastic, and further, that the plug strip containing a > > surge suppression device always be placed upon a non-combustible > surface. A > > word to the wise... > > > > 73, Eric Lemmon WB6FLY > > >ummmm.....how come the fuse/circuit breaker didn't trip? Sounds like the >problem is a defective breaker to me!
Nope, the breaker did just as the designer intended. The power strip is designed to carry 7 to 10 amps and the breaker is sized for that. The MOV went into avalanche mode and conducted - pulling several amps. Now do the math, 120v AC times, oh - pick a number - 3 amps, is 360 watts of heat generated by a device the size of a large disk ceramic capacitor. You don't think that 300+ watts of concentrated heat isn't going to do some damage? And hot enough to melt a plastic housing? And maybe char an area of carpet? Or catch the melted plastic on fire? (remember, most inexpensive plastic housings are made from petroleum-based plastics). Remember that 3 amps is a lot less than the trip point of ANY power strip fuse or breaker. And it could be 5, 10 or more if it's a 15 amp breaker. Mike WA6ILQ
