"bud--" wrote in message
.. .
wrote:
On Oct 14, 11:53 am, bud-- wrote:
RBM wrote:
wrote in message
...
On Oct 13, 5:42 pm, "RBM" wrote:
wrote in message
...
On Oct 12, 10:47 pm, (Doug Miller) wrote:
In article
,
wrote:
And I have to disagree on that one. I can find the code section for
you later,
Yeah, you do that. We'll wait.
You didn't have to wait long. Here it is. No need to get sarcastic
and snippy.
" 210.21 Outlet Devices.
(B) Receptacles.
(1) Single Receptacle on an Individual Branch Circuit. A single
receptacle installed on an individual branch circuit shall have an
ampere rating not less than that of the branch circuit."
That is clear as day. A 20 amp single receptacle has an ampere rating
greater than that of the circuit, hence it MAY be used. If they
wanted to prohibit using a 20 amp or greater single receptacle on a 15
amp circuit, all they had to do was say the receptacle has to have a
rating EQUAL to the circuit.
but essentially it comes down to this. The code draws a
distinction between circuits with only one outlet and those with
more
than one. With more than one outlet, it says you can't use a 20A
outlet on 15A circuit.
Wrong. It says you can't use a 20A outlet on a 15A circuit, period.
You've
apparently become confused by the provision that you can put 15A
outlets
on a
20A circuit as long as there's more than one outlet. That's perfectly
OK.
Putting a 20A outlet on a 15A circuit is a violation in all cases,
without
regard to how many there are.
But for a circuit with only ONE outlet, the
code says the outlet rating must have a current rating at least
equal
to the circuit rating.
It says no such thing. It is, for example, a violation to put a 50A
outlet
on
a 20A circuit.
Actually it does say exactly what I said it does, as shown above.
You're the one who's confused, which is OK, but why the attitude?
Hence, a 20A single outlet can be use on a 15
amp circuit.
No, it cannot. Look at Table 210.21(B)(3), where it lists the
permissible
receptacle ratings. For a 15-amp circuit, the maximum receptacle
rating
is
"not over 15".
Yes, let's look at that section. In the same section where it starts
to explain those tables it starts off with:
"210.21(B)(3) Receptacle Ratings. Where connected to a branch circuit
supplying TWO or MORE receptacles or outlets, receptacle ratings shall
conform to the values listed in Table 210.21(B)(3)"
The added emphasis is mine. Since we are talking about using a SINGLE
20 amp outlet on a 15 amp circuit, those tables do NOT apply.
I agree that it doesn't make any sense to me.
Doesn't make any sense to me either. Of course, that's because you're
completely wrong about the rules.
Actually it's quite clear that you're the one who's wrong here. A
simple admission to that and apollogy for getting snippy will suffice.
I think the reason for that initial statement in the code, is because
a 40
amp receptacle can be wired with a 40 or 50 amp circuit, but the table
makes
it perfectly clear that a 20 amp receptacle can't be wired with a 15
amp
circuit- Hide quoted text -
That table is preceeded by the statement, which I provided and is
shown above, that says it applies to circuits with TWO or more
receptacles. If they wanted it to apply to ALL receptacles, including
single outlet ones, they could have simply omitted the word TWO, but
they did not. And the section right before it clearly covers the
case of a SINGLE receptacle and allows a receptacle with a current
rating equal to or greater than the circuit to be used.
It doesn't make a lot of sense to me, but that is what it says and it
allows using a single 20 amp receptacle on a 15 amp circuit.
[trader]
I agree that 210 does not prohibit a single 20A receptacle on a 15A
circuit

But a 20A receptacle is virtually never allowed under 406.3-B. It would
make sense to at least point to 406 in 210. The logic is probably that
406 (Receptacles...) is the primary article and is modified by 210.
There is a reference to 210 in 406.3.

Most people would not be dumb enough to want a 20A receptacle on a 15A
circuit (there seems to be one exception).



I see what you're reading, but there is no text that says any
receptacle,
single or duplex, can have a rating higher than the circuit feeding it.
[RBM]
There is text that you can put a 20A receptacle on a 15A circuit.

There is no text in 210 that you can't have a higher rating, like 20A
(or 50A, or 100A) as the single receptacle.

There is text in 406.3 that you can't put a 20A receptacle on a 15A
circuit. This is what we all (except one) expect.

--
bud--- Hide quoted text -

- Show quoted text -

I don't think the issue ever was what we expect. I would not have
expected the code to allow a 20 amp receptacle on a 15 amp circuit
either, which is why I brought it up in the first place. I also would
not wire a circuit that way, because it's misleading at best. But
what one expects and what is actually written in the code can be two
different things.

I think there are actually three differing opinions on this subject.
It looks like cl and I read the code as allowing a single 20 amp
receptacle on a 15 amp circuit. Doug makes the claim, which I think
is totally bogus, that the table in 210.21 (B) (3) says it is not
allowed. But that is just plain wrong, because that table is
preceeded by verbage that says it applies to circuits with two or more
receptacles. I believe you and I agree on that point.

Then there is your position, which is that while not prohibited by
section 210, it is prohibited by 406.3. That is a new point, which I
had never heard used before. But let;s look at what that says. It
doesn't actually say you can't put a 20A receptacle on a 15A
circuit. What it says is this:

406.3 (A)

"Grounding type receptacles shall be installed only on circuits of the
voltage class and current for which they are rated, except as provided
in Table 210.21 (B)(2) and Table 210.21(B)(3)."


A 20A receptable is rated to handle 0 through 20 amps of current. A
15 amp circuit falls in that range, so I would interpret the above to
mean that the 20A receptacle is permitted. Especially in view of the
fact that when they specifically address the issue of a single outlet
they could have just said that in the case of a single outlet you must
use a receptacle with a rating equal to the circuit, but they did not
and instead said this:

" 210.21 Outlet Devices.
(B) Receptacles.
(1) Single Receptacle on an Individual Branch Circuit. A single
receptacle installed on an individual branch circuit shall have an
ampere rating not less than that of the branch circuit.

A 40A receptacle is rated to handle 0-40A. Would it be allowed on a 15A
circuit?

The rule should be expected to be in the article on receptacles, which is
406.

The rule is (leaving some details out) that for 15 and 20A circuits,
receptacles "shall be be installed only on circuits of the voltage class
and current for which they are rated" (same as you quoted). On a 15A
branch circuit you can only install a 15A receptacle and on a 20A circuit
you can only install a 20A receptacle. You match the receptacle rating to
the branch circuit rating. In 406.3-A it does not say 'voltage class and a
current not less than the branch circuit'.

Then there is the exception - Table 210.21 (B)(2) and (B)(3). They allow a
15A receptacle on a 20A circuit. There is no reference to 210.21-B-1
(single receptacles).

There is not a problem with a 15A receptacle on a 20A branch circuit
because listed plug-in equipment is apparently tested to be safe on 20A
circuits (which it all can be plugged into). And a 15A receptacle is rated
for 20A total.

The problem with installing a 20A receptacle on a 15A circuit is obvious
to everyone (with one exception). It does not make sense the NEC would
allow that (although the NEC does make mistakes). IMHO it is not allowed
in 406.3-A. It is not explicitly allowed in 210.21-B-1. Would 210.21-B-1
allow a 40A receptacle on a 15A circuit?

But there is a difference. While 406.3-A is specific to 15 and 20A branch
circuits, 210.21-B-1 (single receptacle) is general, including for
instance a 60A receptacle on a 40A circuit - allowed by 210 and not
covered by 406-3-A. For 15 and 20A circuits use 406.3-A.


Suppose instead of talking about receptacles, 406.3 talked about wire
and said wire gauge shall only be installed on circuits of the voltage
class and current for which it is rated. Would that mean that I
couldn't use 12 gauge wire on a 15 amp circuit?

But 406.3 isn't about wire gauge and there are reasons to use a larger
size wire.

There are obvious reasons (to most people) why you don't want a 20A
receptacle on a common 15A circuit.

==================
The Holt discussions did not consider 406.3.

--
bud--


For me, 406.3A is the most confusing. If it were based solely on 210.21,
it's clear that the table doesn't cover single receptacles, and that single
receptacles must be rated not less than the circuit. 406.3A uses the term
"of the voltage, class and current" , it doesn't say "not less than", or
anything that offers flexibility, other than to use the table in 210.21B3,
which is not applicable to single receptacles.
In conclusion, I'm still scratchin my head, other than the fact that, while
there is no danger in using a receptacle rated higher than the circuit,
there is no practical reason to do it, and it could just lead to confusion.