Can wiring to a light off a 20A circuit be done in 14ga wire?
What about wiring to an upstream 15A receptacle?
Or, does all wiring on a 20A circuit breaker need to be at least 12ga?

Thanks

"blueman" wrote in message
...
Can wiring to a light off a 20A circuit be done in 14ga wire?
What about wiring to an upstream 15A receptacle?
Or, does all wiring on a 20A circuit breaker need to be at least 12ga?

That is correct; with the slight exception if the #14 wire has a separate
15a breaker on it.
Some people will use #14 on a lighting switch leg, on the theory that it
couldn't possibly see more than a couple amps; but it is a code violation.

You simply cannot use 14ga wire on a 20 amp circuit.

Any electical inspector that sees that in a box will simply
flag it and make you change the line or the breaker.
(just as an FYI)

If you pull too much near the 15amp side and exceed
the limits it wont stop for another 5amps. In effect you
can be overloading the line. It may not happen on your
lighting idea, but why bother with the risk for a few bucks
more on getting the correct wire.

Using 12ga on a 15amp is perfectly fine. Its nice that down
the road if you need to upgrade you can just change
the outlets and breaker and you got a 20amp line.

Tom

blueman wrote:
Can wiring to a light off a 20A circuit be done in 14ga wire?

It will work just fine for a switched light but is technically a code
violation, even if the wire ampacity is 20A (which 14 gauge THHN-2 is.)
You could argue that you were using the 10 foot tap rule (or 25 foot, I
don't remember which would apply better here), but you'll get shot down.

What about wiring to an upstream 15A receptacle?

No. What if somebody plugs a 10A load into both halves of the duplex
receptacle, or extends the circuit someday?

Or, does all wiring on a 20A circuit breaker need to be at least
12ga?

Yes. 12 ga is not that much more expensive than 14 ga, and your time is
worth something; do the job right.

Best regards,
Bob

blueman wrote:
Can wiring to a light off a 20A circuit be done in 14ga wire?
What about wiring to an upstream 15A receptacle?
Or, does all wiring on a 20A circuit breaker need to be at least 12ga?

Thanks

I would say never. I hear folks say it can be used between switch and
bulb, but that just does not seem right. Breaker protects the wiring,
nothing more nothing less.

Perhaps someone puts in a heavy duty bulb of some sort that is broken
and begins to draw lots of current. The circuitry wont be protected by
the breaker. An all around bad idea.


To put it simply, the wiring should _always_ match the breaker.

--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

"blueman" wrote in message
...
Can wiring to a light off a 20A circuit be done in 14ga wire?
What about wiring to an upstream 15A receptacle?
Or, does all wiring on a 20A circuit breaker need to be at least 12ga?

Thanks

This depends on the situation. If the box has #12 and your UL listed light
fixture is #14 probably #16 then it is fine.

If your adding the #14 yourself no must be #12.

Open your electric water heater some day, you will have at least #10 feeding
#12.
It is inside a UL listed and labeled appliance, there for ok doky.

"SQLit" wrote in message
...

"blueman" wrote in message
...
Can wiring to a light off a 20A circuit be done in 14ga wire?
What about wiring to an upstream 15A receptacle?
Or, does all wiring on a 20A circuit breaker need to be at least 12ga?

Thanks

This depends on the situation. If the box has #12 and your UL listed light
fixture is #14 probably #16 then it is fine.

Huh? What are you saying?

If your adding the #14 yourself no must be #12.

Open your electric water heater some day, you will have at least #10
feeding
#12.
It is inside a UL listed and labeled appliance, there for ok doky.

Yeah, I noticed mine is. I presumed that was because the #12 wires are THHN
and between two things rated for higher temperatures. No?
Still, it seemed like a foolish place to save $0.02.

Toller wrote:

If your adding the #14 yourself no must be #12.

Open your electric water heater some day, you will have at least #10
feeding
#12.
It is inside a UL listed and labeled appliance, there for ok doky.


Yeah, I noticed mine is. I presumed that was because the #12 wires are THHN
and between two things rated for higher temperatures. No?
Still, it seemed like a foolish place to save $0.02.



If the wires melt and burn within the water heater housing, what is the
end result?

--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

wrote:
On Thu, 09 Feb 2006 08:41:35 -0500, dnoyeB
wrote:


Open your electric water heater some day, you will have at least #10
feeding
#12.
It is inside a UL listed and labeled appliance, there for ok doky.


Yeah, I noticed mine is. I presumed that was because the #12 wires are THHN
and between two things rated for higher temperatures. No?
Still, it seemed like a foolish place to save $0.02.



If the wires melt and burn within the water heater housing, what is the
end result?

--
Thank you,


A 4500w water heater only pulls 18.75a. There is plenty of safety
factor in a #12 as a "fixture wire" but if it is protected by a 30a
breaker the "branch circuit" conductors must be #10.


if it only pulls 18.75a, why not put 12 everywhere? Protection is not
tied to the loading of the appliance, its tied to what happens under
failure conditions. If that appliance fails with a resistive short, it
can pull up to the load allowed by the circuit protection.

More likely they ensure that melted and burned wires wont start a fire
within the appliance. And that the appliance is obviously bad anyway so
loosing some wiring is not a significant penalty. You dont want to
loose wiring in your wall due to a bad appliance.

So 12 is not 'safe' in terns of it not failing, but in that if it does
fail, its not goign to cause any additional significant damage.



--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

wrote:
On Fri, 10 Feb 2006 08:18:11 -0500, dnoyeB
wrote:


wrote:

On Thu, 09 Feb 2006 08:41:35 -0500, dnoyeB
wrote:



Open your electric water heater some day, you will have at least #10
feeding
#12.
It is inside a UL listed and labeled appliance, there for ok doky.


Yeah, I noticed mine is. I presumed that was because the #12 wires are THHN
and between two things rated for higher temperatures. No?
Still, it seemed like a foolish place to save $0.02.



If the wires melt and burn within the water heater housing, what is the
end result?

--
Thank you,


A 4500w water heater only pulls 18.75a. There is plenty of safety
factor in a #12 as a "fixture wire" but if it is protected by a 30a
breaker the "branch circuit" conductors must be #10.


if it only pulls 18.75a, why not put 12 everywhere? Protection is not
tied to the loading of the appliance, its tied to what happens under
failure conditions. If that appliance fails with a resistive short, it
can pull up to the load allowed by the circuit protection.

More likely they ensure that melted and burned wires wont start a fire
within the appliance. And that the appliance is obviously bad anyway so
loosing some wiring is not a significant penalty. You dont want to
loose wiring in your wall due to a bad appliance.

So 12 is not 'safe' in terns of it not failing, but in that if it does
fail, its not goign to cause any additional significant damage.



You notice I said the "branch circuit" conductors ARE required to be
#10 (when using a 30a breaker). If you are not happy with what a
recognized testing lab says is OK under the covers of listed
equipment, you will have to take it up with them. I'm sure a testing
lab would point you to facts about exactly how much temperature rise
you actually get in 12ga wire with a 30a load. It is far from being
enough to damage a 90c conductor.


You misread my post. I didn't say it was not OK within the appliance.
What I said was that it was OK, *not* due to the fact that it wont burn,
but to the fact that it wont cause a fire when/if it does.


Just because you can put a 12Ga wire on a circuit within an appliance
does not mean you can do that outside of the appliance.


--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16