Inside a box.....

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Open Neutral

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Inside the Beltway
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Engineer
I was asked:

Take a steel box, say 12" x 18" x 8". It holds a number of open frame relays that control both legs of 240V circuits. Said box is adjacent to the breaker panels. Assuming everything is now compliment.....

Now:
But the homemoaner gripes about the relay hum. Approaches that come to mind are mounting relays on a backboard of ABS or Fiberglass or such, and lining the box with Sound Soak type material, etc. Is there any Code issue in such material inside there?

[It's a ~$4E6 house, so I guess he can afford to complain..]

[I have other possible approaches, such as using DC relays, but....]
 
Open Neutral said:
... Approaches that come to mind are mounting relays on a backboard of ABS or Fiberglass or such, and lining the box with Sound Soak type material, etc. Is there any Code issue in such material inside there?
...
Click to expand...
AFAIK, Code does not specifically prohibit anything from being placed in an enclosure. About the only issue I can think of under Code is barriers required to be inside separating different Class circuits and/or types of wiring.

That said, AHJ approval is required.
90.4
90.7
110.1
110.2
 
Open Neutral said:
I was asked:

Take a steel box, say 12" x 18" x 8". It holds a number of open frame relays that control both legs of 240V circuits. Said box is adjacent to the breaker panels. Assuming everything is now compliment.....

Now:
But the homemoaner gripes about the relay hum. Approaches that come to mind are mounting relays on a backboard of ABS or Fiberglass or such, and lining the box with Sound Soak type material, etc. Is there any Code issue in such material inside there?

[It's a ~$4E6 house, so I guess he can afford to complain..]

[I have other possible approaches, such as using DC relays, but....]
Click to expand...

Use a solid state relay. http://www.newark.com/crydom/d1240/...ookieCreated=true&CAWELAID=120185550001249815
 
iwire said:
Use a solid state relay. http://www.newark.com/crydom/d1240/...ookieCreated=true&CAWELAID=120185550001249815
Click to expand...

Considered, but SSR's are {usually at least} SP NO, I need DP NC. Further, they have far more voltage drop than a mechanical relay.

SWAG it to be 1V, and with say 60A, that's 60 watts per relay. Double that for both poles. There are multiple relays.

Plus, I'm not sure how 2 SSR's in series will react if it's a pure 240V load not 120/240.....

That said, I've been looking into same.
 
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