Solenoid from a car door, any car door: are they legal in 2016?

[Mr V]

Originally Posted by aldaeron

I wish I had more time to ask a Q&A before ordering because I really only need a pulse type solenoid for what we're doing, but a pulse lists its wattage as well over 10 W as shown here My curiosity is if the continuous version of the solenoid uses 4W and the pulse version of the same series uses 40W for short periods of time, does it meet R29? My guess was no.

-matto-

The difference between an intermittent and continuous duty solenoid that otherwise looks identical will be the resistance of the coil. The intermittent version will have higher resistance than the continuous duty version. The high resistance version will not generate much heat but the continuous duty version will and thus heat up, potentially to the point of failure if left energized significantly longer than the rated on time or duty cycle.