I took Paul Miller’s suggestion and tested the windings on the 50A Leach and the Lancair- supplied contactors.

 

  I connected a 24V power supply to the coil terminals without any load across the points and after 36 hours continuous the Leach case was slightly warm to the touch. All of the terminals checked out- electrically isolated from the case, low resistance across the points.

 

  The Lancair contactor was very different. Within about 15 minutes the case was too hot to hold comfortably. The winding and contact terminals grounded to the case in an apparently random fashion with changing values of resistance and voltage. When the unit cooled down the terminals were electrically isolated and coil resistance was as new so the coil wasn’t shorted internally and the unit seemed to be fine. As power was reapplied and the coil began to warm the process repeated.

 

  I haven’t heard of any problems on the LML so these contactors seem to be adequate for the job. Oildyne says the pump is intermittent duty (no percentage given) so it might be toasted before any problem with the contactor showed up. OTOH the contactor is relatively heavy and seems marginal- people using them might consider something different.

    –Bill Wade