Branch circuit for well

[George Stolz]

Scenario: New residence.

30A OCPD supplying 10-2 home run to water maintenance closet for well pump. 12-2 from disconnect to pressure switch contacts. 12-2 to (1.5 HP pump box-gizmo to protect pump). #12 jumpers field installed in box. #10 from box to pump.

How illegal is this, and was I justfied in ripping it down and replacing all the #12's with #10's in a righteous fury?

Edit to add: There is no control circuit. The conductors directly feeding the well pump go from 10 to 12 to 10 on a 30 amp breaker.

[ February 01, 2005, 12:09 AM: Message edited by: georgestolz ]

 

[bphgravity]

Re: Branch circuit for well

I believe the installation was probably okay as it was.

Branch circuit conductors are sized at 125% of the FLC of the motor. Asumming this is either a 120 volt or 240 volt pump, #12 would be more than adequetefor a 1.5 hp pump motor. This is assuming there is also an overload device sized at 125% of the FLC. The branch circuit circuit breaker then becomes a ground-fault and short-circuit device only. This in most cases will be sized greater then ampacity of the conductors.

See sections 430.22, 430.32, 430.52, T430.148, and 240.4(G).

 

[George Stolz]

Re: Branch circuit for well

Despite the fact that prior to whatever protection the well-pump box provides (it's not the disconnect), the wire has already been stepped down to 12?

Why run 10? Why not run 12 and put it on a 20 amp breaker?

If it were sized for voltage drop, shouldn't it maintain 10 the whole way, or is it just as effective having twenty feet of 12 in the middle?

(At least it was temped in when I got there. It wasn't complete.)

 

[bphgravity]

Re: Branch circuit for well

Perhaps a 20A OCD was not large enough for the starting current of the motor? In any case, the design does appear to be poor, however not necessarily a code violation.