Who else uses PPTC Resettable Fuses (PolySwitches or Polyfuses)?

Yes, with about the same results. For protecting wires, transformers, solenoids and motors they are fine. They are similar to Slo-Blo fuses as far as trip time goes. If you are looking for instantaneous trip they are not for you.

I use a PTC for installations when I have the Cruise Commander Lite, I put one in the motor leads.  I use a 1A trip model, and I've only been able to trip one by really overloading the locomotive.  It's only there to protect against motor stalls.

I use a 1.65 trip model in a tether for a steamer if I'm sharing the pickup rollers for reliability.  Since it rarely sees a load in normal operation, I've never had one of those trip, but I've also never cooked the tether since using them.

Like John I've placed them in tmcc engines after frying a few boards. I used RUE300 3A 30volt and haven't lost a board since.  Since then I've also added 1.5ke36ca transient voltage suppressors across the output of the transformer where it attaches to the track. Putting the tvs in the engines is tempting too but I haven't tried it yet. The advantage to putting it in the engine is when you take your engine on the road and run on a club or friends layout. 

I use them on terminal strips for my train board for track and accessory feeders.  Also put one in my bell & whistle diode block for my floor loops.  I did it to cut power quickly after derailments.  And I also put them in my passenger cars during led upgrading.

I use the 6 Amp variety, one per power district.

Here they are on one of my power distribution panels.

I agree that the reaction time is a little slow on these.

I also want to put something like a 2 Amp version in my engines to protect the electronics.

Big_Boy_4005 posted:

I use the 6 Amp variety, one per power district.

Here they are on one of my power distribution panels.

I agree that the reaction time is a little slow on these.

I also want to put something like a 2 Amp version in my engines to protect the electronics.

First of all, gorgeous wiring job! That clearly took some time, effort and $$. Hoping it has paid off for you.

Secondly, I totally like GRJ's approach to protecting engines through the use of relatively low trip point (1a and 1.65a) PTCs. If I ever scrape together enuff $ to buy the type of engine/electronics that need protection (I have mostly PW stuff), I will buy a range of the devices just to see what works best for each engine.

Here's a list of some PTCs that others here on the forum have used for a few different applications.

PTC and TVS - Some Commonly Used Sizes and Part Numbers (from other threads)

If you have a PTC that you like using for a particular application, please let me know and I can add it to the list. You can post here or my email is in my profile.

I had one odd ball experience with PTCs and I have not figured out what happened.  I added the PTCs where the wire busses from my transformers went out to the track and accessories.   One of them actually started burning one evening with a real flame. I think this one was on the output of a KW but it was a few years ago.  I was in such a panic I wish i had paid more attention to what was going on at the time.  I have to guess at this point that I had a load on it that was greater than five amps but not enough to trip it. The ones I bought are marked with the beta symbol which I think is Bourne, rg 500 0334s.  Needless to say, I am using glass fuses now.....