Connecting Electrical to Exterior Outlet

I am pouring a patio and would like to wire a remote recepticle and lighting into an existing exterior outlet box. The existing box is in a stucco wall. New concrete will be poured directly below the existing box, and I plan to bring conduit out of the new concrete directly below the outlet and tie the new wires in to the existing box. I would like to avoid breaking stucco, and am wondering if there is some kind of exterior box extender that could be mounted and sealed to the existing permanent box that would let me tie in the new conduit. I would also like to keep a functional outlet at this location. Does such an extender exist ?
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Yes. Raco makes them and I'm sure a few other manufacturers produce them as well. They are called single-gang extension adapters. For 1/2" conduit try a Raco #5412-0 or Raco #5399-0. For 3/4" try Raco #5413-0 or Raco #5403-0. You will probably have to go to an electrical supply house to buy them.
I suggest that you stub up from the concrete using rigid metal conduit. That point where the conduit emerges from the concrete is where PVC tends to break after a few years of abuse. Keep the PVC under the concrete and underground.
John Grabowski http://www.mrelectrician.tv

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Great info. Thank you John.
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