Hobbs wiring

[mr bill]

A better way, is to add a N.O. pressure switch that is on the oil pressure line. When the engine starts and you get oil pressure, the switch closes and power is applied to the Hobbs meter. On my firewall is mounted a tee, one end is the oil pressure sender and another end is the N.O. switch and the third end is the oil pressure line from the engine. This is how it is done by Piper and Cessna.