On May 8, 10:52*am, bud-- wrote:


I would like to know the Joule ratings. The problem, as you say, is
there is no standard way to measure the energy rating and some
manufacturers apparently use questionable ratings. That has led some
other reputable manufacturers, like SquareD, to not include Joule ratings.

Here is a couple of nice article for evaluating SPD’s.

Is the Joule rating of an SPD important?
While conceptually an surge protection device (SPD) with a larger
energy rating will be better, comparing SPD energy (Joule) ratings can
be misleading. More reputable manufactures no longer provide energy
ratings. The energy rating is the sum of surge current, surge
duration, and SPD clamping voltage.
In comparing two products, the lower rated device would be better if
this was as a result of a lower clamping voltage, while the large
energy device would be preferable if this was as a result of a larger
surge current being used. There is no clear standard for SPD energy
measurement, and manufacturers have been known to use long tail pulses
to provide larger results.
Additionally confusing this issue is the possibility that the rating
is just the energy absorbed, diverted, or the sum of both. NEMA LS 1
by specific omission does not recommend the comparison of SPD’s energy
ratings. Comparison of single shot surge ratings and let-through
voltages is considered sufficient.
http://www.nemasurge.com/help.html

http://ecmweb.com/mag/electric_compa...d_performance/
http://www.control-concepts.com/pdfs/01_005.pdf
http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf 2.5.1 Joule
Rating