DIYbanter - View Single Post - Suggestion for 24V/120V relay to control new outlet?

Bud--

wrote:
On Thu, 13 May 2010 17:16:30 -0500, bud--
wrote:

wrote:
On Thu, 13 May 2010 09:43:48 -0500, bud--
wrote:

This is generally read to say that the entire class 2 system is inside
that enclosure. You can't take a wire out of there to another place
and still call it class 2.
If the wires can't leave the box there is no particular usefulness in
being class 2 - they can be class 1.

It would allow the use of a class 2 listed transformer.

The section quoted above says class 2 wires are "introduced solely to
connect the equipment". Reasonably read, "introduced" can mean to enter
the enclosure from the outside.

IMHO "introduced" clearly allows external class 2 wires to enter a box
to connect to "the equipment connected to Class 2 ... circuits".

As I said in my previous post, 725.136-D has 3 options for class 2
wiring entering a box that has power wiring. Separation by at least 1/4"
is one option. Only if the first 2 options are not used does 136-D
explicitly require the class 2 wiring be class 1.

It is common practice for class 2 thermostat wires to enter a
"compartment" in a furnace/boiler where there are exposed insulated
power wires. IMHO the section I quoted allows that practice if the class
2 wires are kept separate from the power wires.

Again this is a listed assembly and I bet a new one has some kind of
plastic barrier when it is shipped. It may not make it through the
installation process and electrical inspectors don't really look
inside that equipment.

It is an interesting question I will bring up with the IAEI..

I agree that it is listed apparatus and should generally be beyond your
purview (if wired according to manufacturer instructions). But it is
compliant with what I understand is permitted by 725.136-D (class 2 and
power wires in the same "compartment").

I dug out an old copy of UL913 which is for intrinsically safe
apparatus. As you are no doubt aware, intrinsically safe wiring is a lot
touchier than class 2. The standard has several methods to separate
field wiring terminals for intrinsically safe circuits from power
wiring. One of the methods is to separate the terminals by 2" (and
there are requirements for insulation rating and securing the wiring).
Intrinsically safe wiring can be in the same enclosure (like a control
panel) as the power wiring and terminate in the enclosure. The
intrinsically safe wiring is certainly intended to leave the enclosure.

You can certainly try it and see what your AHJ says but I doubt it
would fly with any inspector I know.

The AHJ would be arguing with what is explicitly allowed by UL.
And, IMHO, what is allowed by 725.136-D.

That also means you CAN pull a low voltage cable and line voltage
cable in the same raceway,as long as you have separation where they
terminate.

Hold your nose legal ... Pull your CAT5 and Romex through the same
conduit, extend the CAT 5 through the box and terminate it in a LV
ring next to the box. Some might argue that you need a separation
between the place where you split open the RX jacket and the exit of
the CAT 5 but if you went in and out in the back of the box with the
LV cable, stuffed in a mylar insulator and split the RX jacket on the
outside of that you comply.
A little dodgier is CAT 5 and THHN in the same pipe. Most AHJs will
not let that fly.
You have posted that previously and it seemed quite reasonable.

When I looked at 725.136, it looks like class 2 and power can be in the
same raceway *if* the power (or class 2) is wired in UF (725.136-I).
What allows class 2 and Romex? Do the jackets constitute a "barrier"
(725.136-B)?

BTW there are plenty of inspectors who say I am wrong about this "both
in the same pipe" thing. They are far more restrictive about how class
2 and line voltages need to be separated.

But inspectors enforce the same code.......

I thought your options sounded reasonable.

IMHO 725.136-I clearly allows THHN power wires in the same raceway with
class 2 that is in UF. Now if they would just make #18 UF...

I always liked taping UF with class 2 to the power conduit for
installations like external condenser/compressors.

--
bud--