[RE-wrenches] 30 amp disconnect/40 amp breaker

[Blake Gleason]

Greg,

It would seem that the 30A disco, if 100% rated, is fine with the max
circuit current,  and I'm sure it's fine with the voltage.   The unfused
disco is not going to be the limiting factor for your short circuit
current.  (The disco is probably 100kAIC.) Rather, the limiting factor
would be the (40A / 10kAIC?) breaker.  In other words,  I don't see how
705.22(4) rules out the 30A disco.

Blake Gleason, PE
Director of Innovation
& Technical Excellence
Sun Light & Power

On Wed, Aug 21, 2019, 9:52 PM Greg <greg at remotepowerinc.com> wrote:

> All, thanks for the responses.  I greatly appreciate it.  Yes the 30 amp
> disco is non-fusible and rated for full load.  True, you have to check the
> manu's specs.  You *always* should check the manufacturers specs.
> Anyway, 705.22(4) indicates the disco:
>  *Have ratings sufficient for the maximum circuit current, *
> *available short-circuit current, and voltage that is available *
> *at the terminals*.
> That rules out a 30 amp disco in this case.
>
> Best,
> Greg Egan
> Remote Power Inc.
>
> On 8/21/2019 3:20 PM, Greg wrote:
>
> All, the engineer came back with 705.22(4) to back up his request.  I
> think that's the end of it.  Per code he is right but since the inverter is
> only capable of 25 amps, the only time the 30 amp disco would see more than
> 30 amps is if the inverter was shorted.  If that's the case opening the 30
> amp disco at that time could cause failure.  Pretty unlikely event.
> Although I think installing a 60 on this circuit is an overabundance of
> caution but I'll be installing a 60 amp disco on this one.
>
> Best,
> Greg Egan
> Remote Power Inc.
>
>
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