nuisance trip central vac breaker



That's not my point. Forget the motor operation. What happens when it, or the outlet itself, shorts?

Again, not the point. OCDs are there to protect the wiring during a failure. Motors, or devices with motors never fail?
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On 13-Nov-17 7:59 PM, snipped-for-privacy@notreal.com wrote:

Au contraire, IS the point and why there's a difference in NEC for dedicated motor circuit...
...
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OK, why? The fault that the OCD is there to safe is still there.
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On 14-Nov-17 8:32 PM, snipped-for-privacy@notreal.com wrote: ...

Precisely _because_ it is a motor circuit and motors are different and NEC understands that.
It's all in Section 430 but short story is as outlined above; ampacity of the wire is determined for FLA of the motor; the breaker/fusing is sized to allow to be able to handle inrush starting current and the LRA or similar _continuous_ overcurrent protection is _NOT_ provided by the breaker but the _REQUIRED_ thermal protection for the motor (and thereby the wiring as well).
IOW, there's a second layer of protection besides the branch circuit breaker of a "normal" branch circuit you're used to that isn't in the lighting/general use circuit which relies on the one device for both functions.
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On 15-Nov-17 8:53 AM, dpb wrote: ...

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And, if the thermal protection is built into/comes with the motor, that's allowable; larger motors of the woodworking-shop class generally have "heaters" located in the starter enclosure that can be simply inline fusible links that serve the purpose or the "thermal reset" button in a motor that is just a circuit breaker or there are similar resettable heaters as well.
Doesn't matter _where_ the device is, specifically, but must be there by Code.
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On Mon, 13 Nov 2017 20:59:05 -0500, snipped-for-privacy@notreal.com wrote:

The SHORT circuit protection is still there. short is an instantaneous very high current spike that will still trip the breaker IMMEDIATELY
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wrote:

But that is *not* why the OCD is there. Are you saying that motors can never fail?
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On Tue, 14 Nov 2017 21:33:21 -0500, snipped-for-privacy@notreal.com wrote:

No, I'm saying motors have built-in thermal protection, and a "motor failure" will increase current by 5 amps pretty darn quick - so the circuit breaker will still protect the wire. I wouldn't go stupid and install a 30 (or heaven forbid a 40) amp breaker.
I'm pretty sure the high-mag breaker will do the job anyway, given the symptoms and amp draw readings I'm getting.
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wrote:

What's the difference? Nothing can go wrong.

This sounds like a much better option.
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wrote:

Each trip diminishes the capability of the C/B as well.
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wrote:

Correct - but replacing the original breaker with a brand new identical breaker did not help - and thermal tripping degrades a breaker significantly more than magnetic tripping - which does not cause any appreciable heating in the breaker.
Magnetic tripoping is instantanious tripping - thermal tripping is delayed. (due to prolonged overload)
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On 11/11/2017 3:16 PM, Clare Snyder wrote:

I had to put a high-trip mag breaker on one circuit which was serving my shop dust collector. Around here it was a matter of going to the nearest big-box store -- both Lowe's and Home Depot had them available -- and this is in a decidedly less populated area than Ontario.
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wrote:

Home Despot Canada doesn't carry them at all. Nor does Lowes Canada. Rona Canada used to carry them, Rona was recently absorbed by Lowes. Home Despot in the USA apparently DOES carry them but both Buffalo and Detroit are about 3 hours away.
In Quebec Reno Depot carries the high magnetic breakers in their stores. That's well over a 5 hour drive.
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On 11/12/2017 2:03 PM, Clare Snyder wrote:

Sounds like the sort of crap that we had to put up with living in Alaska except that sometimes it was a 3-hour flight rather than a 3-hour drive. Your situation seems so odd -- these are scarcely some sort of rarely-used magical devices and many applications really do need them all the time.
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wrote:

A lot of the problem here is American companies who see Canada as too small a market to bother complying with our bi-lingual labelling requirements. No french labels means no sale in Canada. I think youcan sell in Quebec with french only labelling - which may be why SOME things are avaiable in quebec only - the quebec based outlet doing their own labeling?
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