Joules - surge protector question

JoeH wrote:
I see surge protectors with differing values for joules.... but it doesn't say what is better ... is higher better than lower values ?

As with many things in life there's much more to the story of surge protector joule rating than simply saying "higher is better" ... because in fact it may not be necessarily so, particularly when we're talking about RV specific surge protectors which use MOVs (Metal Oxide Varistors) to direct excessive current surge & spikes to ground. From this wiki article ...

"The joule rating is a commonly quoted but very misleading parameter for comparing MOV-based surge protectors. A surge of any arbitrary ampere and voltage combination can occur in time, but surges commonly last only for nanoseconds to microseconds, and experimentally modeled surge energy has been far under 100 joules. Well-designed surge protectors should not rely on MOVs to absorb surge energy, but instead to survive the process of harmlessly redirecting it to ground. Generally, more joules means an MOV absorbs less energy while diverting even more into ground"

Rather than accept WAG commentary from those who claim "more is better" you'd be far better off to accept that manufacturers such as TRC and Progressive Industries know what they're going and have selected joule ratings appropriate for the task at hand. One also needs to understand the very real possibility that MOVs in these various surge protectors, exposed to sufficient strikes, can be expected to fail ... in other words, a surge protector is not necessarily a one time, lifetime purchase. The potential for MOV failure is the very reason I chose to invest in a hardwire Progressive EMS-HW30C which is field serviceable by myself rather than the portable equivalent which is a sealed unit and must be returned to the manufacturer for repair.