Would running wire above the bathroom (i.e., above the ceiling) require conduit or GFCI protection? Planning to run 4/3 Romex. Thanks.
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6/3 NM-B on conduit
- Thread starter jansant
- Start date
ambudriver03
Member
Need a bit more information. Where is the wiring terminating? Garage? Outlet? Exterior surface?
Is it terminating to an outlet, or a hard wired EVSE?
If terminating to an outlet, most likely requires gfci breaker.
EVSE, does not.
Wiring wise - Romex should be secured to the studs when possible.
The space above the ceiling is not generally a moist location, and not required to be in conduit. (if you have a lot of moisture in your attic, that's leaking from the bathroom, you have a separate issue)
4/3 Romex is extremely difficult to turn in a L-body
50 amp circuit, 6/2 NM-B is OK; 60 amp circuit would require 4/2 NM-B.
In a garage, at or above 8 ft, you can install NM-B, drop down to the required height for a receptacle, switch or equipment, i.e. Wall Connector. NM-B should only be installed in conduit where needed for protection from physical damage.
In a grade-level garage you could instead use metallic clad (MC) 6/2 wire for a 60 amp circuit; MC 8/2 is rated for up to 55 amps so it would be OK for a 50 amp circuit.
ATPMSD
Active Member
While 4/2 is certainly good for a 60 amp circuit, you may find #6 THW easier to work with, but does require the use of a conduit.
Some have stated their experience, difficulty in locating 4/2 NM-B (even questioning whether it exists; yes, you can find 4/3.) My electrician installed 50 a amp charging circuit in my home using 8/2 metallic clad MC, THHN. (70 ft run from the panel in the basement into the attic and then over, down into my garage.) For those dry locations where MC can be used MC is faster, easier to install than conduit and pulling wire.
I have a grade level garage. So it sounds like I can go with a 6/2 NM-B in a conduit OR 6/2 MC without a conduit (with a 60 Amps breaker). I have about a 42' run in the garage and 30' run in the basement.
I am waiting on my electrician to give me a recommendation and a quote, but I wanted to be informed when I discuss this with him.
Thank you all for your suggestions.
I am waiting on my electrician to give me a recommendation and a quote, but I wanted to be informed when I discuss this with him.
Thank you all for your suggestions.
ATPMSD
Active Member
NM-B does not require conduit, should not to be installed in conduit except as needed for additional protection from damage. For 60A you would need to use 4/2 NM-B (assuming this wire can be sourced.) It sounds like one continuous run of 6/2 MC would work in this installation.
Working With Metal-Clad (MC) Cable
The maximum wall charger output is 48A for a Model Y according to Tesla - and the 6/2 NM-B is rated at 55Amps. I know this is a hotly debated topic...but I am tempted to just go with 6/2 instead of 4/2 - assuming my licensed Electrician agrees with this. It sounds like a 6/2 MC is a safe way to go, w/o a conduit, and it seems that it is rated at 75 Amps (if I read this info correctly). I will wait for my Electrician's recommendation and will let you know what he comes back with. Thank you all again.
ATPMSD
Active Member
This is a common mistake. The 55A rating applies to an intermittent load. For a continuous load you are only allowed to pull 80% of the wire’s rating. So the 55A wire is limited to 44A for a continuous load. This exceeds the 48A continuous load of the wall connector.
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Metallic Clad (MC) cable is manufactured with THHN wire. 6 gauge MC is rated for up to 75 amps.
The use case of NM-B is that it can be run by itself in non-accessible areas. So you can run it in crawlspaces under floors, in attic areas above ceilings, and inside insulated sheetrock walls. These are a good majority of normal residential circuit paths. But if it has to come out of a wall, where it's exposed along the surface where people can get at it or pull on it, then that NM-B can continue, but needs to be inside conduit for that area.
But I'm going to reiterate @ATPMSD 's point about the amp rating, but maybe restated another way. The wire needs to meet the amp RATING of the circuit. The setting for 48A on the wall connector is a continuous amp rating. Electric code specifies for continuous current loads, that the circuit rating must be 125% of that continuous current. So for the 48A continuous, the circuit rating must be 60A. The 55A rating of 6 gauge NM-B simply does not meet a 60A circuit rating. Period.
The receptacle installed in the video is a NEMA 14-50, rated for 250V and 50 amps. The breaker rating is not visible or stated, would be 50 amps. 6/3 NM-B is rated for up to 55 amps so no issue; NM-B can be installed in conduit where it would otherwise be exposed to damage or human tampering. No mention of using a GFCI breaker (not sure how old is the video.) Current NEC specifies GFCI for EV charging circuits.
Yes, that's allowed as needed. This is a common case depending on what locations the wire run goes through. If it has to go down through an insulated wall or in attic areas above ceilings, then you would normally be using Romex there anyway. And then if it transitions to need to go outside, along the surface of a wall, then you would need to put some conduit around it.
A bathroom or kitchen is not a wet/damp location. Neither is a finished garage. all dry locations.
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