Replacing the pronoun with its antecedent, we have:
The _compressor_ must go through a spike.
There are reasons why everything you _can_ do is not something you _should_ do. Maybe the folks at IFI have made sure that First team members are safe from their mistakes, but just because you got away with it, doesn't end it.
The Spike relay is two circuits in one package. The input is an LED which needs the appropriate current and (thus) the appropriate voltage and polarity.
The pressure switch has no source of 5 V, which is what the Spike needs on its input. If you wired the input, via the pressure switch to +12V, which is the only voltage available (except in your electronics) you could
a) apply overcurrent and blow out the LED input to the Spike, or
b) apply high reverse voltage and blow out the LED input to the Spike, thus ruining the Spike.
If you wire the switch to the RC digital input, and put the compressor-controlling Spike on an appropriate output, the Spike is supplied with the design-nominal voltage/current level signal, and the compressor can be officially turned off before and after the match.
The advantages to doing it this way include not being told to rewire and get re-inspected, and not having erratic (or no) operation of the Spike.
Hope this helps.
