nanog mailing list archives
Re: DC power versus AC power
From: rs () seastrom com (Robert E. Seastrom)
Date: 30 Dec 2002 09:18:40 -0500
"Barton F Bruce" <barton () gnaps com> writes:
Typical 120/208V small branch circuit breakers in small buildings and homes have an interrupting capacity rated at 10,000 amps, and should not be deployed where that can be exceeded. It will be on the label.
It's worth noting that the interrupting capacity of the aforementioned breakers is 10,000 amps *AC*, and that said circuit breakers should not be used in *DC* applications despite the fact that the voltage is less than half as much and the fact that they're downstream from a 600A fuse (and have smaller wire in the circuit that will naturally limit how many amps can go into a short anyway). I'm hazy on the theory (perhaps someone more knowledgeable can post it), but my understanding is that with AC the arc has a chance to quench 120 times per second (ie, every time there's a zero crossing), and with DC that opportunity (obviously) does not exist. Bottom line is that one should buy breakers and fuses that are designed for use in DC powerplants, rather than trying to cheap out with something you picked up at Home Depot or Pep Boys. I'm sure I'm wasting my breath since _nobody_ who reads NANOG would ever try to cut corners to save a few bucks... :) ---Rob
Current thread:
- Re: DC power versus AC power, (continued)
- Re: DC power versus AC power Stephen Sprunk (Dec 29)
- Re: DC power versus AC power joe mcguckin (Dec 29)
- Re: DC power versus AC power Stephen Sprunk (Dec 30)
- Re: DC power versus AC power David Lesher (Dec 30)
- Re: DC power versus AC power Robert E. Seastrom (Dec 30)
- Re: DC power versus AC power Stephen Sprunk (Dec 30)
- RE: DC power versus AC power blitz (Dec 29)
- Re: DC power versus AC power Barton F Bruce (Dec 30)
- Re: DC power versus AC power Robert E. Seastrom (Dec 30)
- Re: DC power versus AC power David Lesher (Dec 30)
- Re: DC power versus AC power David Lesher (Dec 30)