I'll take that as meaning the rated holding current is not printed, and that the breakers may well be designed for the rated holding current, and then labelled for the trip current. Thanks. That's interesting. You have a truly unique system that I'd never heard of. That 80% rule is really strange. In Australia, the breakers are labelled and specified for the rated holding current. This labelling follows the international and European standards, e.g. IEC/EN EN 60898-1 ... with a single letter prefix for specifying the instantaneous tripping current as a _multiplier_ of current, not as a _percentage_ as you do. The 20 stamped on your breakers would be a C16 stamped on our breakers, which means a rated holding current of 16 A, and an instantaneous trip current above 80 A and up to 160 A. Instantaneous meaning less than 100 ms (five cycles at 50 Hz). Special loads are given different instantaneous trips. Your "nothing else matters to us" is carefully noted. This is a difference between engineering and electrical code contracting. ;-) Procedures that reduce risk by reducing thought, and therefore possibilities for error. Thanks to Eoin for the links. The products there don't have any 80% rule; the Eaton products use the C and D tripping curves. They list IEC/EN 60947-2, and also UL. On Mon, Feb 16, 2015 at 09:02:49PM -0600, Richard R. Pope wrote: > James, > The breakers sold and used in the US are rated at 80% continuous=20 > current of what is stamped on the handle. This is required by UL labs=20 > and the NEC. So if the handle has a 20 stamped on it the instantaneous=20 > trip current is 20 amps and the maximum continuous holding current is 16= =20 > amps. This is the law here. You can download the datasheet for whatever=20 > model that you want more info on. To us installers all we care about is=20 > what is the number on the handle, is it an arc-fault breaker, (this was=20 > required as of 2013 in the US), and is it UL listed. Nothing else=20 > matters to us. I have never done any additional research beyond that. > Thanks, > rich! >=20 > On 2/16/2015 8:01 PM, James Cameron wrote: > > Is the rated holding current printed anywhere on the breaker? > > > > As previously quoted by Allen, "A CB is designed and evaluated to > > carry 100% of its rated current for an indefinite period of time under > > standard test conditions." > > > > So what is the technical difference between a rated holding current > > and a rated trip current? > > > > On Mon, Feb 16, 2015 at 06:45:04PM -0600, Richard R. Pope wrote: > >> James, > >> Two things are important for installers. The amp rating that is > >> printed on the handle.. Then there will be a label on the side and the > >> installer needs to make sure that it is UL certified. Whatever is on t= he > >> handle is the rated trip current. No other information is required by > >> the installer. > >> Thanks, > >> rich! > >> > >> On 2/16/2015 6:37 PM, James Cameron wrote: > >>> I'm not surprised, but as I'm not in the US, it's only of academic > >>> interest. As I said, I'm more interested in the physics and the > >>> specification of the parts. > >>> > >>> Is the label required to be different to that specification? If so, > >>> that's a can of worms. > >>> > >>> On Mon, Feb 16, 2015 at 06:20:51PM -0600, Richard R. Pope wrote: > >>>> James, > >>>> In the US the NEC is a legal requirement. Local codes must be= at > >>>> least as restrictive as the NEC. Also if the wiring is not done to c= ode > >>>> and the fire is caused by the poor wiring the insurance does not hav= e to > >>>> pay. If someone is hurt or killed than the person who did the wiring= is > >>>> now open to criminal and civil charges. > >>>> I always consider the code as a starting point. As I said bef= ore I > >>>> wire all of the 15 amp 14 gauge circuits to 20 amp 12 gauge specs. I > >>>> also put in any where from 20 to 100% more circuits depending on the > >>>> life style of the home owner. In Wisconsin 100 amp panels are requir= ed. > >>>> I always install 200 amp or larger panels. > >>>> Thanks, > >>>> rich! > >>>> > >>>> On 2/16/2015 6:08 PM, James Cameron wrote: > >>>>> Agreed. > >>>>> >=20 > --=20 > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 James Cameron http://quozl.linux.org.au/ --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .