"This circuit should not be less than #12 wire and should be protected with a 20 Amp time lag fuse."
Not being aware of this detail until now, I was just going to use a regular 20-Amp circuit-breaker (I ran #12 wire). Please advise. Thank you!
Bill
Correction, I ran #10 wire, for this.
Also when I say "regular", I do mean 240v (2-pole).
Thanks! Bill
Prepare for a few breaker pops, hope the fuse panel is close to the saw.
In trying to answer my question, I learned that "all circuit breakers are "time delay" by nature of their design."
So, I guess we'll see what happens...
Progress in the shop is continuing after a delay or two in recent years caused by major events.
Bill
Nope, he'll be fine (as he discovered in further research and posted) as circuit breaker as opposed to fast-acting fuse has enough inherent lag time for the motor...
Congratulations, Bill! I've had my Unisaw (Delta 36-844) for 6 years and have had no problems with #12 Romex (about 15ft from sub-panel) and this (standard?) Siemens breaker:
As others are pointing out, you'll be fine. Old fuses would blow with the initial spike of current when saw motor kicked on. A modern circuit breaker needs to heat up to trip (except in the case of a short) so it can't get hot enough to trip from the very short current spike of the motor's start-up.
At least that's my layman's explanation of it. :-)
On 06/08/2016 3:59 PM, -MIKE- wrote: ...
"Fast-acting" ones, yes, "slo-blo" (specifically designed for motor loads and the like with an initial short-lived high-current transient) wouldn't.
...
The fuse had to heat up, too (in fact, it had to actually melt) but the idea is correct; they are designed to handle motor loads inherently to be general-purpose; it would be a real pain to have to have separate breakers for the application.
The time for a dead short to heat up and trip will be quite a lot shorter than that for the motor start; while a motor start is a (relatively) high current (say 3X or so of full load), that of a dead short is I=V/(R-->zero) --> Infinite.
Don't know why you'd say that. He's well within the current loads with #12 wire and an 20A breaker.
So... you basically agreed with the previous poster...
Well, yes, I said that in the very beginning that his general ideas were/are correct but added some amplification as to "why" and "what" actually is going on.
Was that needing comment for some reason?
Maybe my fault for having missed that up front. Sorry.
You're good to go. Household circuit breakers are pretty much equivalent to "slow blow" fuses.
You may want to put a 30A breaker on it. In any case, be sure the breaker you use is "listed" for the wire you're using.
Nonsense. My 3HP Unisaur has been on a 20A (240V) circuit, with
20-30' of 12-2 W/G between it and the panel for years, with zero trips. Come to think of it, it was ~50' in my last house.
No, in addition to the thermal detector, circuit breakers have a magnetic trip. A high enough current will trip the circuit before the thermal detector can trip.
If wired for 120 V I would say yes, if wire for 240 V probably not.
Mark
20 amps is 20 amps. Don't matter whether you're running 120 or 240.
Not true. The motor will draw half the current at 240V, as it would wired for 120V.
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