Installing Electric Vehicle Charger (aka EVSE)

[transferguy]

Posted By: JeffInCO

I'm getting ready to install an electric vehicle charger in my garage. I guess the device is more correctly classified as "Electric Vehicle Service Equipment" (EVSE), as the charging electronics are really built into the car (a Nissan Leaf, in my case).

The EVSE that I selected is a SquareD model EV230WS. It supplies a maximum charge current of 30 amps (at 240 volts) to the vehicle, and therefore requires a 40-amp circuit to supply it. The EVSE does not need a connection to neutral; rather, only the two hots and the ground. The manual calls out 40 amp overcurrent protection on the circuit, though it contains internal fuses on both hot legs which appear to be 60 amp. I plan to re-purpose an existing welder circuit in my garage, which is on a 50 amp breaker and wired with 6-3 copper NM to a 14-50R receptacle outlet.

As I see it, there are two options for connecting the EVSE to the existing circuit:
1) Attach a corded plug to the EVSE and plug into the existing 14-50R outlet (the EVSE itself would be screwed to a nearby stud in the wall). I'm not sure if this is code compliant; I've read elsewhere that some inspectors have frowned on this as they consider it to be voiding the listing of the EVSE since it was not manufactured with nor necessarily designed to be corded. If I took this approach, attaching a range cord should be straightforward. I guess I would swap out the 50 amp breaker for 40 amp, although the 14-50R receptacle remains. Apparently, there is no such thing as a 40 amp 240 volt receptacle.

2) Option 2 is to remove the existing 14-50R receptacle and hard-wire the EVSE. Currently, there is a 4x4 metal box behind the 14-50R receptacle, in the wall, which I do not want to dig out. What would be the correct way to transition from the existing 4x4 box to the EVSE? Do I have to go through conduit to one of the knockouts on the EVSE, or can I position the EVSE over the 4x4 opening in the wall such that the EVSE completely covers the hole and the conductors enter the EVSE through one of the rear knockouts on the EVSE? For the hard-wired approach, I would definitely replace the 50 amp breaker with 40 amp.

Thanks in advance for any feedback!

Jeff

[transferguy]

posted by: suemarkp

Go with option 2, as that's most likely your only choice. Depending on where the knockouts are on the EVSE box, you could:
Mount it directly over the 4" square box so that the EVSE totally covers the box and the wires come through a knockout on the back.
Put a blank plate with knockout on the 4 square box and use a short piece of flex conduit on a 90 degree fitting to get from there to the EVSE if it has a side knockout.
Put a box extension on the 4 square box and then a blank plate. Run a short conduit nipple form the box extension to a side knockout in the EVSE box.

If the lugs on the EVSE won't take your #6 wire, you may need to wire nut on some #8 copper pigtails. You may need to do that anyway as the #6 wires are probably not long enough to reach the EVSE lugs even if mounted right on the 4 square box.

Mark
Kent, WA

[transferguy]

Posted By: JeffInCO

Mark,

Thanks for your reply.

If it is allowed to mount the EVSE box directly over the 4x4 opening, I will go ahead and do that as it is the simplest. I will probably do as you said and add the #8 pigtails, though, more to give me extra wire to work with (I think the lugs on the EVSE can take the #6 wire.) Do I need any kind of fitting in the knockout hole on the EVSE? The EVSE box is plastic, so the knockout hole edges wouldn't abrade the insulation, but I would guess that the code still requires some kind of fitting in the hole.

Thanks,

Jeff

[transferguy]

posted by: suemarkp

I'd put a chase nipple on the EVSE box knockout (the rounded end ends up inside the 4x4 box). On the inside, use a nut on the bushing and then screw on a PVC bushing on top of the nut. Since your box is plastic it would be nice to find PVC versions of this, but I've only seen them in metal. It should not be required to bond this lone metal nipple, but if you have to use a bonding bushing instead of the plastic bushing.

Another option is a threaded PVC nipple with nuts on both sides of the EVSE to secure it. Then, thread a PVC bushing on each end to make it rounded and smooth.

Another option would be a 3/4" NM (Romex) clamp through the knockout and use a short piece of 8-2 NM cable in that clamp for your connections.
Last edited by suemarkp; 11-07-2014 at 09:47 PM.

Mark
Kent, WA