We're moving into a house that has older two-wire ungrounded wiring.
Short of the expense of rewiring the entire house, I'd like to make it
as safe as possible for people and equipment. I've already put in GFCI
outlets in bathrooms, kitchen, garage, outdoor locations. So from a
people safety perspective I think that's about as good as we can do,
and grounding would not improve that situation.

Now for equipment, I'm thinking about a panel-based whole house surge
suppressor, since the lack of grounding will defeat any point-of-use
surge suppressors. There seem to be quite a few units available with
similar specs: clamping voltages in the 400-500V range, energy
dissipation on the order of 1000 joules, maximum current 50,000 amps,
5 ns response. One example is the Intermatic 1G1240R. These seem to
generally be described as sufficient for protecting appliances but the
vendors still recommend point-of-use surge suppressors for electronic
equipment.

There is also a product sold by Tytewadd, which clamps at 130V, maximum
current 10,000 amps, and 1.5 ns response. It is specifically
advertised as protection for "sensitive equipment". But... it has a
total energy dissipation of only 70 joules, far far less than the
previous class of units.

Does anyone have experience with the Tytewadd devices? They're not
that cheap -- $150. I'm in a generally low-lightning-risk location
(Northern California, bay area) so maybe this kind of moderate
protection is sufficient. But 70 joules is less than the specs on a
rinky dink power strip. Should I save my money, ask an electrician to
rewire a couple outlets in key locations, and stick with power strip
surge suppressors?

-- Dave