Sanity check request for OUTDOOR DIY installation of EVSE

[wwhitney]

For example say the NM-B goes through the wall into a disconnect, or a weather rated metal junction box, or if that junction box also has a receptacle in it, all mounted to the outside wall. Are these considered damp/wet and thus NM-B should not enter them?

No, that's OK, the interior of a proper weatherproof box is considered dry.

Cheers, Wayne

 

[QueenBee]

For example say the NM-B goes through the wall into a disconnect, or a weather rated metal junction box, or if that junction box also has a receptacle in it, all mounted to the outside wall. Are these considered damp/wet and thus NM-B should not enter them?

No, that's OK, the interior of a proper weatherproof box is considered dry.

Cheers, Wayne

Well that's good at least, thanks. So really then the answer to this is to enter the EVSE from the rear if they've provided space for that.

 

[shikataganai]

Revised simpler/cheaper/no conduit! EVSE + self-wiring plan:

- Siemens 30A Versicharge EVSE, in rear-fed configuration, to be mounted on the outside wall of the house/garage
- 40A GFCI breaker at the box (Siemens recommends the use of a GFCI breaker whereas Leviton does not)
- 8/2 NM-B cable routed indoors stapled to the rafters, spliced at an interior LB junction box with a Multi-Cable Connector to two 8 guage THHN/THWN-2 wires plus a 10 gauge ground
- Run said THWN-2 wires through a 3/4" hole drilled through the wall, entering directly into the back of the Siemens EVSE, following Siemens' own "fed-from-behind, hard-wired installation" instructions (no outside junction box or conduit runs involved)

The 30A Siemens EVSE is $850 vs. $1,100 for the 40A Leviton unit on Amazon, 8-2 NM-B cable costs roughly $0.90/ft vs. $1.30/ft for 6-2 NM-B, and this proposed "fed-from-behind" installation method allowable with this Siemens unit seems to me to allow for elimination of all conduit… right?

For example say the NM-B goes through the wall into a disconnect, or a weather rated metal junction box, or if that junction box also has a receptacle in it, all mounted to the outside wall. Are these considered damp/wet and thus NM-B should not enter them?

No, that's OK, the interior of a proper weatherproof box is considered dry.

Hmm. Would the above mean that I could legitimately run 8-2 NM-B right into the back of the Siemens EVSE in my above, revised plan (without splicing to THHN/THWN-2 at an inside junction box)? That'd make life even easier! My sneaking suspicion is that because it's a rubber grommet involved here rather than a connection to sealed conduit I should stick to splicing indoors and running THWN-2 through the wall. Thoughts?






In diagram form:

#2 in the above, the "Fed from Behind entrance", corresponds to the grommet in the photographic lower left in the below image, through which I'd feed the THWN-2 (or NM-B? see above):

 

[QueenBee]

I'm curious what others have to say about using romex entering from the back. My amatuer opinion would be that you could just have romex go through the wall and enter from behind. I'd use a clamp for romex like this with the locking nut on the outside of the EVSE. If you felt the romex needed extra protection you could have the romex enter a short piece of conduit as well. If there is any doubt that this will pass inspection you can always ask the inspector a head of time. At least in Bellevue they've been happy to discuss things and provide guidance.

The reason you see the large fancy strain relief on the inside is because I think they installed it backwards so it would be flush. It's what you'd use to secure and provide strain relief to the plug and cord installation. In a hardwire installation you can certainly use a standard conduit threaded fitting and a locking nut, etc.

If you ended up switching to THWN instead of the Multi-Cable Connector I'd just use cheap blue wire nuts.

 

[shikataganai]

As a belated update to this thread:

We did indeed lease a 2013 SL. I never installed level 2 EVSE as per the elaborate plans in this thread, though, as level 1 plus occasional level 3 top-offs on the rare high mileage day have sufficed.