[TowerTalk] NRTL listing Re: lightning arrester suggestions

[john simmons]

Please note that *any* lightning protection device is totally worthless unless the grounding system to which it (they) are connected is adequate. Just saying, "I've got 4 8' ground rods and I'm bonded to the electric service panel" is not enough. You must MEASURE the ground system resistance! This really isn't that hard... do your research, learn something and sleep better during thunderstorms.

73,
-de John NI0K

On 12/15/2025 5:51 PM, Jim Lux wrote:





Most of the time the requirement is for listing by a "Nationally Recognized Testing Laboratory" of which UL is but one.  For instance Los Angeles county requires that any electrical equipment sold be listed by a NRTL (this was a big problem when cheap PCs were being imported, none were listed, and the county would go around to computer stores and ding them).
There's some exceptions in the ordinance, which comes out of a California Electrical Code requirement which itself is adapted from the NEC (NPFA 70).

There is also an exception if "the thing you're installing" is approved by a licensed PE.

And a lot of times, a foreign recognition  (like CSA or TUV) works. CE is looked at askance because it's "self certified" by the manufacturer. If you actually care, you have to see what the manufacturer actually claims - the CE mark just says that what they're selling matches what they say.  (and of course, there are lots and lots of imports which are "marked CE" but have seen no analysis or test)





On Mon, 15 Dec 2025 13:49:04 -0800, Jim Brown <jim at audiosystemsgroup.com><mailto:jim at audiosystemsgroup.com> wrote:

On 12/15/2025 10:13 AM, jim.thom jim.thom at telus.net<mailto:jim.thom at telus.net> wrote:


The ICE, now Morgan arrestors work superb. They use a static drain
resistor, then a DC blocking cap, then the shunt inductor, then the GDT.




BTW -- in my professional life in pro audio, we had to deal with the
safety certification requirement for any installed systems that were to
be inspected, and it came to light that almost none of the equipment we
need to use for high quality systems were certified. At that time (about
25-35 years ago), there were three recognized testing and certification
agencies -- UL, CSA (the Canadian agency), and ETL (Electrical Testing
Laboratory). UL, based in the US, was VERY expensive, which was why
smaller companies didn't spend the money to get certification, and those
that did went to CSA.

The pro audio industry got together and pushed UL to reduce the costs
associated with their testing, and some went to ETL. It took about five
years, but eventually nearly all of the gear we needed to specify
carried one of those listings.

73, Jim K9YC





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