Are dew strips polarity sensitive?

[Skipper Billy]

Are dew strips polarity sensitive?

The reason I ask is I have bought a second hand dew pad for my secondary mirror and the cable has been cut.

Inside the insulation are two white wires which to my small brain suggests that its not polarity sensitive or they would have been red and black.

Its this one https://www.altairastro.com/kendrick-dew-heater-for-ritchey-chretien-secondary-mirror.html

But before extending the wire and soldering on a phono plug, plugging it in and potentially blowing up my 4 strip dew controller I thought it was prudent to ask !!!

Thanks in advance.

 

[Bizibilder]

They are usually just a length of resistance wire and therefore not polarity sensitive.  Similarly one made from a series or ladder of resistors will not be polarity sensitive either.

If you have a meter then the resistance reading "both ways" should be the same.

[Skipper Billy]

Cheers Roger - will check the resistance - never thought  of that! 

[SonnyE]

As Roger said not usually.

Now good workmanship dictates you exercise prudent care for your plugs. Usually the center, or tip is the Positive, while the shell or shank of the plug is negative, or Earth.

Keeps things tidy for the future.

Some controllers can be sensitive to polarity though. But your dew strips are a lot like a incandescent light bulb, not caring which way the power flows through them.

Clear as mud, right.