Help- voltage going sky high- don't know why - (Nov/11/2010 )

Hi

Our group is having a great difficulty with our big protein gels.
We usually fix our gel running at 40mA but recently the voltage has been maxing out, on one occasion the heat was so much that one of the plates cracked.
We have changed our all of our buffers, 1x running buffer, buffer A & buffer B, numerous times, tried running an empty gel, changed the tanks, the power supply and even the power socket but NOTHING seems to help it.
Also the buffers seem to work fine in the mini protein gel equipment.
We are now running it on constant volts (200V) but the mA is going down so that the gel will run for ever, which isn't ideal.

We have ran out of ideas so any suggestions would be greatly appreciated.

It really sounds like your buffers do not have enough electrolyte to work properly, so to keep the amperage constant, the volts need to increase (which works in the same manner for constant voltage as expressed by Volts=amperage*resistance).

It could also be that the powerpack you are using is not powerful enough to drive the system properly.