Power cut if temps are too high

Tue May 28 04:46:43 UTC 2019

> On May 27, 2019, at 15:10 , Brandon Ross <bross at pobox.com> wrote:
> 
> On Mon, 27 May 2019, Brian Kantor wrote:
> 
>> A simple air conditioner thermostat wired to the EPO switch.
>> For safety, wire two thermostats in series so BOTH have to trip
>> before power is shut off.
> 
> Admittedly it's been a long time since I worked with basic circuitry, but wouldn't wiring them in series cause the circuit to be interrupted if EITHER thermostat tripped?
> 

An EPO works by shunting a pulled-up line to ground. If you wire them in series, then the ground has to be shunted to the first segment which is then fed to the ground side of the second switch which until it is closed will not shunt the pulled up line to ground.

GND———[contact-closure-1]————[contact-closuer-2]—————EPO

Owen