Transformer in junction box

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Old 04-18-11, 07:34 PM
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Transformer in junction box

As I redo the wiring in my house I found a hot line leading to the chime (from the door bell). Inside the junction box is a bunch of wires but tossed in their is what I assume to be a transformer. From there the wires is low voltage one line goes to the chime, one goes to the door bell.

Is it OK for a low voltage transformer to be sitting in a metal 4x4 junction box along with a bunch of other wires? or is there a better way to secure/mount it?

The low voltage line is white and blue wires. It is not shielded in any conduits like the other wires. Is that OK, I assume it is not shielded because it is low voltage?
 
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Old 04-18-11, 07:41 PM
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The xfrmr should be threaded into the box. The hv wires should be in the box with the lv wires outside.
 
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Old 04-18-11, 07:44 PM
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My house (1920s) had the original doorbell transformer in a basement junction box mounted on a wooden backboard near the old meter box. That junction box contained 120V, 240V, and the secondary (16V) doorbell circuits. I am guessing this was not a code violation in the 1920s, and therefore it was grandfathered, but it would not be allowed for new work today.

So, when I rewired I installed a new transformer on the outside of the same junction box. The new transformer was designed with a set screw that is tightened to hold it in a 1/2" knockout, and the primary wires thread through the same knockout into the 120VAC box. The transformer's secondary is terminated outside the box. That meets current code.
 
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Old 04-19-11, 08:05 AM
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Originally Posted by Justin Smith View Post
The xfrmr should be threaded into the box. The hv wires should be in the box with the lv wires outside.
I don't see anything on the transformer that could be threaded into a box. May be it's a real old one?

The HV in the box, LV outside of box, what about the actual transformer itself, should it be in or out of a box? I'll take a pic today and post it.
 
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Old 04-19-11, 08:22 AM
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Originally Posted by MiamiCuse View Post
I don't see anything on the transformer that could be threaded into a box. May be it's a real old one?
Yes.

Originally Posted by MiamiCuse View Post
The HV in the box, LV outside of box, what about the actual transformer itself, should it be in or out of a box? I'll take a pic today and post it.
A new transformer sold for this purpose would have a set screw and bracket for mounting outside of the box. I couldn't find a good photo of the back of the Edwards 596 that I have, but here's their catalog info ... http://www.edwards-signals.com/files/c-590.pdf
 
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Old 04-19-11, 09:40 AM
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Originally Posted by MiamiCuse View Post
what about the actual transformer itself, should it be in or out of a box? I'll take a pic today and post it.
The transformer should be outside the box.
 
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Old 04-19-11, 11:23 AM
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Thank you.

I am assuming the transformer came with the chime as a unit. There is no writing on that either as to what kind. May be I would need to buy a new chime that comes with a compatible transformer?
 
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Old 04-19-11, 11:28 AM
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A standard chime transformer should work.

Exceptions would be if it is electronic and plays a song such as Dixie.
 
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Old 04-19-11, 01:35 PM
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Actually, I see alot of them with threads on them like a connector for rx.
 
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