Purchased a new house that is pre-wired for electric car charging with 4 wires: red, black, white, and 1 uninsulated wire (see picture). I'm trying to install a NEMA 14-50 outlet (for a Tesla) and its pretty straight forward, but hesitant to install the uninsulated ground to the outlet. Is ok to use the uninsulated ground? If not, what would be the alternative?
Electrical – NEMA 14-50 outlet installation – uninsulated ground ok to use
electricalreceptacle
Related Topic
- Electrical – 220 outlet with no ground
- Switched outlet to unswitched usb
- Electrical – Adding new 240v 30 amp outlet by tapping into existing NEMA 10-30 outlet box
- Switch – Pulling outlet from existing 220 switch
- Electrical – Wiring for 30amp RV plug from 50amp (14-50R) outlet
- Installing nema 14-50 with no ground
- Voltage still present after breaker is off
Best Answer
Grounding
Actually, the ground wire needs to go to the metal box first.
The 14-50 receptacle will pick up its ground via hard-flush bare-metal face contact between the yoke of the receptacle and the metal box.
Just make sure the surfaces are clean of paint or rust, and any of those little square "screw keepers" are removed.
You can hardwire a ground from the 14-30 recep to a pigtail coming up from the metal box if you really want to, but it's unnecessary.
Aluminum (don't panic)
Oh, one other thing. That ground wire may be tinned copper wire, but it might also be aluminum. There's nothing wrong with aluminum at these large sizes, but you do need to use special splice techniques that are safe for it. Look closely at the writing on the other wires. If they say "Copper" or "Cu" that settles it. If it says "Aluminum" or "AL" that also settles it. If you can't find any such markings, look end-on to the wires - you'll see copper in the middle of the strands if it's tinned copper. If not, it's aluminum.
If it is aluminum, look at your NEMA 14-50 recep labeling and instructions. Is it UL-Listed for aluminum? Then the wires can attach directly. If not, search for another 14-50 recep, or alternately, pigtail to some #8 copper. The best splice I know of for #6Al to #8Cu is the "MAC Block Connector". They're tough to search for thanks to Apple, but they're similar to large Alumiconns or small Polaris. Get your torques right and make use of the goop provided in the holes.