wrote:
On Wed, 12 May 2010 12:34:57 -0400, "RBM" wrote:

"horizon" wrote in message
...
On May 11, 6:21 pm, "John Grabowski" wrote:
I'm looking for suggestions on a 24volt relay with contacts that can
handle 120V, 7 amps. I'm looking to install it to control a new 120V
outlet that is going in an attic and needs to be controlled by a 24V
signal to turn it on. So, I'm looking for one that is cost effective
and can be mounted in some simple type of wiring box. If it can go in
the same box as the outlet, even better. I'd like to make this code
compliant and do it right. Plenty of space is available as I can
mount just about anything on a stud in the unfinished attic.
Thanks for any input.
I was going to suggest a typical boiler relay like Taco SR501, but then
I
saw both John Grabowski's, and gfretwell's replies, which make even more
sense. I don't know the one John suggested, but if you can live with the
amperage rating, it's a nice self contained unit. The rr7 that gfretwell
suggested, does need a 24 volt power supply, but it has a high amperage
rating, and those relays will last forever.
*Roy I recently discovered these when a customer asked me to fix his
closet
light. I thought that it was a nice compact unit that is made to fit in an
electrical box. It can also be used to replace relay switches. The OP
didn't mention what the load consisted of so I threw it out there for him
to
decide if he could use it or not.- Hide quoted text -

- Show quoted text -

Of the suggestions, it looks like the one that will work is Daring
Dufas's relay in a box suggestion.

http://www.functionaldevices.com/pdf/RIBU1CW.pdf

It meets all my requirements:

easy to mount as it comes in it's own box
15 amps so controlling outlet on 15 amp circuit is OK
takes 24V input
available online for $21

One remaining question. Someone mentioned isolation of the 24V
circuit from 120V circuit? I would assume that since an electrical
equipment manufacturer is making these relays and they are UL listed
they are OK and meet code for my application even though the 24V wires
obviously go into the same box as the 120V wires?

Thanks again for the suggestions

If there is not separation between line and low voltage compartments within
the enclosure, I would recommend connecting line voltage conductors to the
low voltage terminals, then run them outside the enclosure through a
knockout, where you can splice them to typical low voltage conductors.


When you have "low voltage" conductors in the same box as line voltage
the whole low voltage circuit needs to be treated as "class 1" which
means it needs to be treated the same as you would treat the line
voltage. Everything needs to be in a box, conduit or in a cable like
Romex, end to end.
When you have separation you can treat the low voltage side as "class
2" and you can take the liberties we usually have with "low voltage".
It is really a little more complicated than that but you see what the
general implications are.

"725.136-D Associated systems within enclosures
Class 2 and 3 circuit conductors in ...boxes... shall be permitted to be
installed with electric light, power... circuits where they are
introduced solely to connect the equipment connected to Class 2 and
Class 3 circuits, and where (1) OR (2) applies:
(1) The electric light, power... circuit conductors are routed to
maintain a minimum of 0.25 in. separation from the conductors and cables
of Class 2 and Class 3 circuits."

The separation required is 1/4" between conductors. The class 2
conductors can attach to the relay in Dufas's relay box as long as they
are kept 1/4" from power wires

Using a barrier is another method (725.136-B).

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There should not be a problem with using a listed relay/contactor in a
listed box (where the combination is not listed together).

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The relays that gfretwell and John showed take minimal space in normal
boxes, which makes them easy to use in normal wiring (in addition to
having the low voltage wires outside the box). It is an advantage if
they are installed where exposed (like a basement) to replace the relay
in the future. Both are available as 2 wire or latched (momentary) versions.

--
bud--