The outlet needs to remain accessible. If you provide access (maybe via a door on the side of the bump out), it likely can remain. If not, you're going to have to relocate it. You just can't "extend" it out from where it is, as the junctions need to remain accessible as well.

As Ron says, you can't cover ANY outlet that makes it inaccessible. But why can't you plug your devices into one of the two receptacles I see in your photograph?

If this build out is being attached to the wall, then as ron said, the outlets need to be moved so that they are accessible.

But if this 'build out' is actually going to be a free standing piece that's no different than a piece of furniture, then the outlets can remain where they are.

Thank you very much for the feedback. The picture is not my build but would be very similar with an existing plug located behind the structure, as in this picture. However, I would be attaching it to the wall so it will not be freestanding. Every video I've watched and installation instructions I've read for electric fireplaces, suggests simply plugging it in behind the new structure which seems like it would violate a code of some sort. Could it be that it's ok to do that since the insert can slide in and out of the recessed opening, thus being able to access the plug?

The outlet would be considered accessible if the electrical fireplace just needs to be pulled out of the way to access the outlet.

I'm not sure exactly how the code would apply to a fireplace, but its very common to have a receptacle behind an electric range, and you just pull the range out to access it. If the fireplace just slides into place (not bolted/screwed), it seems like a similar situation.

Bruce

The rule on accesibility is that you don't have to disturb a finished surface. Pulling out an appliance or removing an access panel is acceptable. You can't bury it behind a fixed structure.

I really appreciate everyone's input. To be clear, the unit slides into the framed opening but it does get screwed in to keep it secure. It wouldn't take much to remove it but it will be attached.

I'm not sure of the details, but are the screws to keep it secure easily visible? I assume this requirement is that emergency responders must be easily able to pull it out if there is an electrical fire. I would open up the wall behind where the fireplace will be, and see if the outlet box can be moved without extending any of the wires.

There's no provision in the NEC for the ability of emergency responders (other than the new extrernal power disconnect). The rule is boxes need to be "accessible" which means capable of being accessed without damaging the finished surface. Pulling out an appliance provided it can be done without damaging the surround is fine. Screws (even if concealed, provided you can get to them without damaging anything) are fine. Things like junctions for recessed lights, etcc. are way more involved than this.

The only exception is if it were a GFCI. The GFCI test/reset buttons have to be "readily accessible" not just accessible. That means you can't have to resort to tools or move "obstacles" to get to them.

Thanks, Ron, for clarifying this!

One thing also to note if you're covering up an existing receptacle, is that the fireplace (and its surround) doesn't get you out of the "no point on the wall more than 6' from a receptacle." You may need to put one on the surround you're building in order to comply with the code.