Upgrading Whole Home Surge Protector MOVs (Eaton CHSPT2SURGE)

[nobbnobb1]

I have a whole home surge protector (Eaton CHSPT2SURGE). This is the lower end model as compared to the CHSPT2ULTRA. When I took it apart, I noticed it's basically the same PCB as the higher end model, just missing the extra MOVs for higher capacity. Coincidentally, I have a pack of brand new Bourns 20D241K MOVs laying around:
https://www.digikey.ca/en/products/d...0D241K/2799098

The only thing I noticed is that these Bourns MOVs are not thermally protected with a fuse. I'm wondering if it's safe to just simply install these extra MOVs for extra capacity, or is it absolutely required to get a thermally protected version such as these:
https://canada.newark.com/littelfuse...50v/dp/01P8113

Thermally protected MOVs are quite expensive, especially if trying to get one with a lower clamping voltage rating.

Also, even with the MOV upgrade I'm assuming I would leave the circuit breaker at the same rating (15A double pole).

Love to hear your thoughts.

[stj]

never do that.
MOV's always fail short, and a big one will make a real bang - specially if it's got a big supply current

[truclacicr]

Those surge "protectors" are crap.

If you must use one of these devices, then I would pay the extra money for something like this:

https://tripplite.eaton.com/products...tors-explained

[PeteS in CA]

Adding to what stj posted, MOVs are damaged by every surge they absorb. With every surge, the firing voltage decreases a little. Eventually, with many surges, the firing voltage drops to or near the nominal line voltage, at which tome conduction becomes continuous and the MOVs short and/or explode. Depending on the surges' intensity and frequency of occurrence, it may take years to reach the point of self-destruction, but if there are surges it is a question of "when", not "if".

[momaka]

Surge "protector" devices are over-rated anyways - that is, most electronics are damaged by the large EM pulses from nearby lightning strikes, particularly the generation of voltage on long external conductors (wires) on most electronics (e.g. signal cables.) Shielded wires tend to be affected a little less, but can still generate potential differences large enough to damage ICs if the lightning strike is very nearby. Also, most electronics have MOVs in their PSUs already, so the extra "whole house surge protection" is really not needed (nor very effective, since you want your surge protector to capture the spike and disconnect the load if the spike goes way too high / has too much power to open up the MOVs.)

Back to the topic at hand, you could use regular MOVs perhaps with a fuse (ceramic type, not glass) in series so the fuse blows if the MOV shorts out. As for the fuse rating, not sure what would go for the calculation of that. If you want to be "extra-fancy", add 2 series resistors in the 100's KOhms range, a diode, and an LED all in series across the fuse. So if the MOV shorts out and blows the fuse, the LED will light up to indicate that it's blown (and the MOV shorted.) But really, that's more of an idea to toy around with than anything too serious. I've seen similar schemes employed in some powers strips that employ surge protection. Actually, when I get time, I have a US/Canada/North American power strip here that needs attention/fixing. Apparently someone brought it over to Europe and plugged it into 230V AC without knowing what will happen. There's a nice black splatter spot on the back of the plastic of this power strip.