If you are putting a electrical box in a 2x4 for a step light do you have to have a metal plate across the top to protect it from nails since it will be close to the edge of the 2x4 per code?

Don't know that you would HAVE to, but it is a good idea.

If you are using the step lights from CCL they come with there own metal box so you really don't need to put on a plate. You can install the box after the deck is installed so no worry about drilling/nailing into a wire. However it does help to have the holes cut before. In fact I cut my holes with the board sitting on my workbench before it was installed in the deck.

http://www.affordablequalitylighting.com/docs/outdoor/step_deck/recessed/prlb-hs/120v.html

http://www.ccl-light.com/imgs/outdoor/step_deck/recessed/prlb-hs/dim.gif

I see that CCL was sold to Affordable Lighting.

Thanks guys. How about the same question for an outlet. I would imagine maybe a metal box would be better for an outlet.

Actually I used the Carlon dial a depth plastic boxes and you can adjust them for the thickness of carpet. Again they can be fitted into a hole after the fact. You have to modify the mounting bracket by cutting off the ears and bending the small barbs. Then you can screw to the front face or the top of the deck.

http://www.carlon.com/images/ContentPics/B234ADJ.jpg

I used plastic boxes just like Big used. If you run the romex to the bottom side of the box, it will leave you enough room to not have to worry about a nail or screw.