Hi ,

I need a 3" Round Duplex Receptacle Cover or 3 -1/4 inch (I don't know exactly)
However I can only find it in 4 inches.( ironically I did find covers )

(I need it for a 'old' deep round metal electric box that is apparently less then the standard 4'' size of today's round box's)

Will this work?
3 Inch Rd Duplex Covers - MUL11005 | Wholesale Electrical Supply Company (http://www.foxelectricsupply.com/content/products/ProductDetail.asp?qsCatID=25927&qsProductNo=MUL11005)

You can use a 4", just drill holes to line up with the box ears or cut one down.

I'd replace the box. Those small boxes and covers are no longer legal size for a reason.

Will this work?
3 Inch Rd Duplex Covers - MUL11005 | Wholesale Electrical Supply Company (http://www.foxelectricsupply.com/content/products/ProductDetail.asp?qsCatID=25927&qsProductNo=MUL11005)
THANKS! That is what I was looking for ,although its designed for octagonal box's it can obviously be used for round box's.

I'd replace the box. Those small boxes and covers are no longer legal size for a reason. you have a point however its not recommended to mess around with old wiring from before the 60's.

Today I was working in a 50's vintage attic and was wondering why the 4" square box in the attic was suspended a couple of inches above the drywall. 3" round box in ceiling connected to a hickey connection and into the 4" box. First 3" box I have seen. Boy, they are small. Had 3 pieces of 14/2 into the 4" and pigtailed wires down the hickey into the 3". I would have used a new work deep ceiling box.