Hello; Has anyone been using Leviton 8599 series GFCI receptacles?
If so, you might want to read this:
The 8599 series have been discontinued by Leviton, and replaced with the 7599 series. I don't know what the differences between the two are, but here's what I found with the 8599.
When back-wired with #12 (THHN) wire, the wires often pull out of the clamps with relatively little force, even after the screws have been fully tightened (I really get them tight!).
Such force can easily be applied to the wires while manipulating them to get them into an outlet box.
I found that twisting the wires or the receptacle causes the most pull-outs.
I own a box of 20 Leviton 8599 which I purchased bran-new from Ebay. There is nothing wrong with these receptacles, except what I believe to be a design flaw which affects the wire clamps used for back wiring.
I believe these can also be side wired, so that is the method I am planning to use for this box I own, unless Leviton decides to replace the whole box with 7599's<g>.
This problem seems only to occur with #12 wire, not with #14. I have not tried with #10 (why would anyone use #10 for a 20A circuit?).
During wiring, I have also found that the problem occurs more often when the bottom set of holes are used on the LINE terminals.
I had an even higher number of pull-outs when I wired with #12 to both top and bottom holes of the terminal.
Another thing that seems to affect the reliability of these contacts is whether or not the wire being inserted is perfectly straight, freshly stripped.
A perfectly straight, freshly stripped wire will tend to hold better.
I have also found that if the screws are loosened, wires re-inserted, then re-inserted and re-tightened, the connection will usually not pull out again.
I have had at least one instance where a previously wired (by someone else<g>) 8599 had the black wire pull right out on me when I started to remove the receptacle from the box.
So, if you're working with the Leviton 8599, and who knows, maybe other models of Levitons as well, be very careful about your back-wired connections. I recommend using side-wire instead, if that is an option.
Here are some photos of the back of the receptacles, wired to top and bottom holes.
The following photo shows wiring to top holes; I found more secure than bottom holes:
And here is the photo of the receptacle wired to the bottom holes, where I have experienced most of the trouble: