bud-- wrote:

Pete C. wrote:
bud-- wrote:
Larry The Snake Guy wrote:
On Aug 14, 2:51 pm, David Nebenzahl wrote:

First of all, it is an approved, UL/CSA tested, and, most importantly,
code-approved (US building code) wiring method. If it was as all-fired
bad as folks here claim, why would it still be allowed? After all, the
building codes tend to err on the side of caution.
However, all kinds of unreliable crap is UL listed. A UL listing is a
pretty good indication that something probably won't kill you or burn
down your house, but says nothing at all about whether it will
function properly.

By coincidence I have the UL standard [15 years old] for "Snap Switches".
For AC-only switches (which is what are commonly used) the switch must
pass all the following at rated voltage:
- 10,000 operations at rated current
- 10,000 operations at rated current and power factor around 0.8
- 10,000 operations at rated current controlling incandescent loads
[high inrush current]
- 100 operations at 4.8x rated current and power factor around 0.5

IMHO this is testing for whether the switch will "function properly".

My recollection is receptacle tests are similarly rigorous and include
plugging and unplugging and operating for a periods at significantly
above rated current.

I think most of us would be very unhappy if fuses or circuit breakers
that are UL listed did not "function properly".

For devices like TVs, it is not possible (or desirable) for UL to
determine if the device is actually useful. The test is whether the
device will "kill you or burn down your house".

Standards may not be perfect. They weren't for #12 backstabs, old
technology #12 and #10 aluminum wire, or devices originally used with
that wire. And standards for GFCIs have changed quite a bit.

IMHO standards are not adequate for #14 backstabs - maybe if they were
limited to #20 wire or smaller....

Building codes put a little more emphasis on
function, but are also updated fairly regularly because things that
were once required are finally proven to be bad ideas.
The NEC has very few equipment construction requirements and I can't
think of any performance requirements.

The 'prime directive' is that "equipment required or permitted by this
Code shall be acceptable only if approved".

"Approved" is "acceptable to the authority having jurisdiction."

The NEC generally has only a few rather general guidelines on what
should be acceptable. "Authorities" generally accept equipment that is
"listed" or "labeled", but it is up to the "authorities".

The NEC did not eliminate #12 backstabs or change requirements for #12
and #10 aluminum wiring.

--
bud--

The standard you quote may or may not test whether the device will
"function properly" as you did not include the pass / fail standards. If
the fail standard is "fire" and the pass standard is "no fire", then the
switch could well stop functioning "properly" well under the cycle count
limit and still pass the test.

The "pass standard", _as I stated_, is that "the switch must pass all
the following". The switch must still work after over 30,000 operations.
And that is only part of the standard.

What you stated, did not include pass criteria as *I stated*.


UL standards, as they apply to wiring components (switches, receptacles,
fuses, circuit breakers, panels, wire, motor starters, wire nuts, ...),
is that those products will "function properly", not just that they will
fail safely.

You say that, but you did not post the actual UL test pass criteria.


For some other equipment, like TVs and industrial control panels, it is
not practical or desirable to test if the device functions as intended,
and the test is that it fails safely. That may involve using "listed" or
"recognized" component parts that are tested to "function properly" as
above.

All UL tests that I'm aware of test only for safety, not durability,
reliability, or functionality. If the device does not cause a hazardous
condition that might result in an insurance claim (note it is
*Underwriters* Laboratories, not *Consumers* Laboratories), it passes.