[BC] Electrical Code

[Dave Karr]

>
> > While logical, assuming the above would be located external to the served
> > equipment...that wouldn't pass an inspection here...
>
>Perhaps I'm out of date, but I recall it being legal at one time if the
>small box's leads were short.

The rules on feeder taps do include limitations on lengths, which vary 
based on application.


> > The feeder branch created by the first three-phase fusible disconnect and
> > the subsequent 'feeder tap' by the single phase fusible disconnect cannot
> > simultaneously supply the three phase load directly without the 
> addition of
> > a second fusible disconnect for the three-phase load.
> >
> > In other words, a "branch feeder" (conductors that supply power to
> > equipment) cannot simultaneously be used as a "feeder tap" (conductors 
> that
> > supply power to other fusible disconnects).
>
>Sounds to me like an unsafe scheme to sell another disconnect switch,

I'm not sure how the additional disconnect would make it unsafe other than 
the potential for confusion as to which one to pull to turn everything off.

My only caution here was that if any of this was going to be done outside 
of the equipment, and was subject to inspection, that such an approach had 
a fair chance of not passing inspection.  The point being that when a 
protected branch is used to feed subsequent fusible disconnects, that this 
branch _only_ be used for that purpose.  I believe there are specific 
exceptions for motors, but they wouldn't apply here.

>  however,
>that being the case, why not include a contactor following the single phase
>disconnect and power it from a transformer across two of the three phases?

That would probably be fine.

A common trip handle to gang a three phase and single phase breaker might 
also work.

>The sensible thing to do is put a breaker in the Tx and feed a CV xfmr with
>one phase of the 3 phase to drop to 120 the same as might be done with a
>large motor starter.
>
>Then there is only a single disconnect for the "appliance" a/k/a Tx and
>anything done inside it is, in most cases, exempt, isn't it?

I agree, and that was my primary point.





--Dave