Power Feed Blowup , the Sequel

"Snag" wrote in message news:serjga$9t$ snipped-for-privacy@dont-email.me... I just got finished a little bit ago replacing the shorted diodes , and the PF is working just fine again . Cause of the diode failure is still a question , may or may not have been an incompatibility between the welder and the PF unit . I suspect that because the two items were powered by different breakers there is a possibility that the diodes were subjected to 220 volts , which could have done this . Point is moot now though , and now I need to decide whether to re-purpose the old one or put it back for a spare . I don't plan any undo-able changes , so I may end up being able to do both !

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I'd be checking the equipment and premises wiring for grounding or neutral bonding faults. I've had an intermittent neutral fault in my house wiring that was cured by replacing the meter box and drop from the weatherhead.

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The house and shop wiring is new , the neutral is good , the ground is good , and this sub panel has the neutral and ground bonded per the recommendation of a local (professional) electrician . This is a Harbor Fright PF unit so original quality may be an issue . As I said , not a big deal at this point .

The house and shop wiring is new , the neutral is good , the ground is good , and this sub panel has the neutral and ground bonded per the recommendation of a local (professional) electrician . This is a Harbor Fright PF unit so original quality may be an issue . As I said , not a big deal at this point .

I did replace the speed control pot a few months ago ... though that seems to be a design fault for most of the PF's that use this circuit board . The cool thing - I figgered out - the numbers on the board identify the component they're next to , like the 33.3k resistor in series with the power-on neon bulb . Come to think of it , this would make a great drive for a ball mill ... an absolute essential if I'm going to make lift powder for the pyrotechnic dev ices I'd like to make !

I did replace the speed control pot a few months ago ... though that seems to be a design fault for most of the PF's that use this circuit board . The cool thing - I figgered out - the numbers on the board identify the component they're next to , like the 33.3k resistor in series with the power-on neon bulb . Come to think of it , this would make a great drive for a ball mill ... an absolute essential if I'm going to make lift powder for the pyrotechnic dev ices I'd like to make !

Are you saying that the sub panel's neutral and ground are tied together? If so, that is a no-no, per the NEC. Tied _only_ at the service (main) panel.

Are you saying that the sub panel's neutral and ground are tied together? If so, that is a no-no, per the NEC. Tied _only_ at the service (main) panel.

---------------------------- Prior to the 2008 NEC version that 3-wire feed was permitted for a sub panel in a detached building, but the sub panel needed its own ground rod. As of

Grounding rules are tricky and evolving, especially for independent power sources like generators and solar panels. NEC says drive a ground rod, Dig Safe says NO, wait until we check.

Some solar panel controllers switch the negative side and having panel negative plus utility grounds (through a UPS) connected shorts the switch.

I'd have to pull the cover and check , but I'm pretty sure we bonded the neutral to ground on that panel . As I said , I was advised by a professional electrician when I wired the shop . Since he is a licensed electrician I figure he knows what he's talking about .

Prior to the 2008 NEC version that 3-wire feed was permitted for a sub panel in a detached building, but the sub panel needed its own ground rod. As of

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