tapping the buss

[bakerbrotherselectric]

I posted a thread yesterday titled - "Customer wants 150amp Welder hooked up".
It was mentioned that a possible solution would be to tap the buss. What would be the proper way to determine whether the buss can be tapped or not? Is it as simple as, the buss extends past the last breakers three inches? Or would it take looking up the model number of the panel, and that tells you? Or is there some designation on the dead front that gives it away?

 

[mdshunk]

Of the times that I've tapped the bus in a "regular" panel, I've changed out the nut & bolt connection where the main breaker bolts to the panel bus with longer bolts to accommodate the added thickness of the tang of a lug. PushMatic panels have the bus run long, past the breakers, so you can drill a hole and add a lug on the bottom (like feed through). For Square D and CH panels, you can get a thing that plugs on like a breaker but is just a set of lugs. No breaker handle or overcurrent protection. This is available up to 200 amp, which takes up 4 spaces. You can also tap the conductors before they hit the mail breaker with something like an H-Tap or Polaris bug.

 

[bakerbrotherselectric]

My plan is to tap the buss at the bottom of the panel. Seeing that this is a 3 phase 208v. panel, and the welder is 1 phase 208v. , would there be any issues going A & B, as opposed to A & C?

 

[Pullnwire]

You could change the main lugs to accomodate stacked lugs, on a and c phase, and then install a disco to protect you taps.

 

[LarryFine]

. . . would there be any issues going A & B, as opposed to A & C?

I'd aim for the two lines with the lower load currents. In other words, avoid the heaviest-loaded phase.