On Wed, 22 Nov 2006 16:43:15 -0700, Bob Axtell wrote:
> New designs require new UL tests. Sorry. But $80K USD seems stiff
> to me, having done several UL/FCC test passes. I don't ever recall
> anything going over $5000 for FCC part 15 / 68 and standard UL.
> Medical UL is more expensive, add another $4000. part 68

Hi Bob,

The reason it's so expensive is that the electrical testing is only a
small part of the testing. This particular product is an automated
fire suppression system control panel that's considered life safety
equipment. It's used to automatically control the release of CO2,
Water Mist, Dry Chemical and what used to be Halon (now FM200)
extinguishing agent. Some of the CO2 tanks are the size of railroad
cars and false discharges are a very bad thing! Failure to discharge
can be almost as bad. These systems get used in nuclear and
hydroelectric power plants, printing plants, computer data storage
facilities, food processing plants, aluminum mills, steel mills and
all kinds of other industrial and commercial facilities. The
liability is pretty huge in a lot of the installations.

The relevant specification for these systems is U.L. 864. Besides
having to pass all the typical electrical safety and emissions
testing, U.L also *functionally* tests the units to comply with NFPA
72 fire equipment standards. U.L. 864 is about a 250 page standard
and only maybe 50 pages are electrical requirements, all the rest are
functional specifications.

They also do compatibility testing with external devices (detectors,
horns, bells, strobes, releasing solenoids, etc.) under all sorts of
electrical and environmental conditions. You basically have to list
and test every device you ever want to have certified to connect to
the system at installation time.

A whole battery of transient testing is done on all the input and
output circuits to simulate near-field lightning strikes. The first
control panel I designed didn't make it through testing without a few
revisions ;-)

In all it usually takes about 60 days in the test lab at U.L. once
the testing is started and it keeps a test engineer busy for most of
that time. It's labor intensive and they run lots and lots of
tests...

One good thing about having been exposed to this kind of design early
in my career is that my designs all tend to be very rugged and very
reliable now (hardware and software). It certainly teaches you to
look at a design and say "How might this thing fail and how can I
keep it from failing? Or if (when) it WILL fail how can I make it fail
safely?".

Matt Pobursky
Maximum Performance Systems



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