My NEMA 14-50 Installation Experience

[little1er]

Can you run a sheathed cable through conduit? I thought wires in conduit had to be individual wires?

 

[Rocky_H]

I am thinking about doing this, but curious what is the size of the main for others who have done it? My panel has a 125A and think that's probably too low to add another breaker

My house has a 125A circuit, and I was able to fit in a full 50A circuit for a 14-50 outlet. It all depends on your particular setup, what your load calculation looks like, how much you currently have used, etc. Load calculation is the main thing.

 

[Rocky_H]

Can you run a sheathed cable through conduit? I thought wires in conduit had to be individual wires?

No, sheathed cable in conduit is not allowed.

 

[tga]

No, sheathed cable in conduit is not allowed.

It is OK if done for protection - you can sleeve romex with conduit for physical protection where exposed to damage (unfinished garage walls, for instance). You have to leave the outer sheath on if the inner conductors are not marked with type info.

Romex often has THHN/THWN inside, but the insulation on the wire isn't labelled. If you remove the outer sheath, you loose the manufacturer's certification info.

 

[P85_DA]

Can you run a sheathed cable through conduit? I thought wires in conduit had to be individual wires?

Based on OP original post he is running THHN..so he is good

Edit : oops his receipt says NM so he is running in conduit lol ..sorry for misstatement there ...

 

[Rocky_H]

It is OK if done for protection - you can sleeve romex with conduit for physical protection where exposed to damage (unfinished garage walls, for instance). You have to leave the outer sheath on if the inner conductors are not marked with type info.

Romex often has THHN/THWN inside, but the insulation on the wire isn't labelled. If you remove the outer sheath, you loose the manufacturer's certification info.

Hmm, perhaps I can get the code input of @eprosenx who's been reading NEC a lot. I was pretty sure it's forbidden to do the sheathed cable inside of conduit because you're double trapping the heat. If it's going to be trapped inside conduit with no air flow, I think that's why it needs the wires to be laid in there loose, instead of also having their heat trapped all next to each other inside the extra rubber sheath. There isn't cooling room if it's sheath + conduit.

 

[nwdiver]

Just to mention, it is almost certainly against local regs to have a non-licensed electrician install this without a permit. Not something people should emulate.

Depends. Everywhere I've lived allows people to perform electrical work on their own home. Some places require a quick test. Some don't require anything. It's not complicated.

I am thinking about doing this, but curious what is the size of the main for others who have done it? My panel has a 125A and think that's probably too low to add another breaker

Also depends. If you have an efficient house your home loads may never be a signifiant portion of the 125A. I've definitely seen panels where the sum of the breakers is >2x the main breaker. If you're worried about overload use a smaller breaker and if you really want to be 4.0 buy the correct NEMA adapter from TELSA or use a properly adjusted HPWC. ~16A @ 240v is enough to charge overnight for most people.

 

[tga]

Depends. Everywhere I've lived allows people to perform electrical work on their own home. Some places require a quick test. Some don't require anything. It's not complicated.

Yes, if you're working on your own home. But if someone is being paid to do the work on someone else's home, the person doing the work usually has to be licensed.

Hmm, perhaps I can get the code input of @eprosenx who's been reading NEC a lot. I was pretty sure it's forbidden to do the sheathed cable inside of conduit because you're double trapping the heat. If it's going to be trapped inside conduit with no air flow, I think that's why it needs the wires to be laid in there loose, instead of also having their heat trapped all next to each other inside the extra rubber sheath. There isn't cooling room if it's sheath + conduit.

Yeah, but - Can Romex (NM-B) be run through conduit?

¯\_(ツ)_/¯

 

[Reid]

To be extra clear: it would be a code violation & safety hazard to put a 60A breaker on a 50A outlet.

Wait, seriously? I ask, because I'm not sure if my HPWC will be here in time and was thinking of having our solar installer/electrician install a 15-50 outlet with a 60a breaker and sufficient wire gauge for 60a so I can later swap in an HPWC on the same wiring (permits filed, inspection required):
What NEMA plug/outlet wiring is closest to HPWC (for later upgrade?)

Is there not a good way to do this? I know it's SORT OF splitting hairs, but if I have the panel capacity, I'd really rather be able to charge the car at 48a vs 40a. I mean, nobody ever complained about having too much horsepower, right?

 

[nwdiver]

Wait, seriously? I ask, because I'm not sure if my HPWC will be here in time and was thinking of having our electrician install a 15-50 outlet with a 60a breaker and sufficient wire gauge for 60a so I can later swap in an HPWC on the same wiring:
What NEMA plug/outlet wiring is closest to HPWC (for later upgrade?)

Is there not a good way to do this? I know it's SORT OF splitting hairs, but if I have the panel capacity, I'd really rather be able to charge the car at 48a vs 40a. I mean, nobody ever complained about having too much horsepower, right?

Breakers are cheap. ~$10-$20. Just install the #6 wire with a 50A breaker for the 14-50 then swap the 50A for a 60A when you get the HPWC.

 

[Revdcaptdick]

Cost me about $200 in Oklahoma and Arkansas to have a licensed electrician install the NEMA for me.

 

[nwdiver]

Cost me about $200 in Oklahoma and Arkansas to have a licensed electrician install the NEMA for me.

Materials included? Either way that's incredibly exceptional. That's what is would cost to install the face plate in most areas

 

[Revdcaptdick]

Materials included? Either way that's incredibly exceptional. That's what is would cost to install the face plate in most areas

Yes, for the most part. I supplied the Receptacles in both cases (they were pretty cheap at Home Depot) and the wire in Arkansas (again, pretty cheap, since it did not take much--the outlet was installed within just a few feet of the breaker box). I think the big difference in location, Arkansas and Oklahoma.

 

[nwdiver]

Yes, for the most part. I supplied the Receptacles in both cases (they were pretty cheap at Home Depot) and the wire in Arkansas (again, pretty cheap, since it did not take much--the outlet was installed within just a few feet of the breaker box). I think the big difference in location, Arkansas and Oklahoma.

We charged a customer $350 recently and that was piggybacking on a Solar PV permit... also a very easy install right next to the panel.

 

[eprosenx]

Hmm, perhaps I can get the code input of @eprosenx who's been reading NEC a lot. I was pretty sure it's forbidden to do the sheathed cable inside of conduit because you're double trapping the heat. If it's going to be trapped inside conduit with no air flow, I think that's why it needs the wires to be laid in there loose, instead of also having their heat trapped all next to each other inside the extra rubber sheath. There isn't cooling room if it's sheath + conduit.

I actually was previously under this impression as well (that NM cable - Romex - is NOT OK in conduit). But I think I was mistaken.

Article 334 of the 2017 NEC covers NM cable.

334.15 "Exposed Work" actually explicitly calls out that it should be protected from physical damage within conduit.

From a practical standpoint I agree, it seems like it would build up more heat this way, though since you are already limited to the 60c rating of the wire due to it being NM cable perhaps that already covers the derate for this kind of application.

That linked "stack exchange" article above has some good nuggets in it. Due to lack of strain relief you are only allowed to leave an electrical box with NM cable in conduit in very specific ways and for only up to 10 feet it would appear. So it is not a common installation method. If you are all in conduit, you should just buy THHN and run that.

 

[eprosenx]

Breakers are cheap. ~$10-$20. Just install the #6 wire with a 50A breaker for the 14-50 then swap the 50A for a 60A when you get the HPWC.

And to be extra clear (which I know nwdiver meant)- You can do 6 gauge in conduit and have it support 60a later once you get the HPWC and swap out the breaker. If it is NM cable 6 gauge would be limited to 50a still even with the HPWC (due to the 60c rating requirement with NM cable). You would need larger cable than 6 gauge if you were doing it with NM cable. If you went with 4 AWG NM cable you would actually be allowed a 70a circuit breaker and the HPWC could be enabled for the max current limit of 56 amps (assuming the load calculations of your panel/service allowed for this large a breaker).

This is what I love about the HPWC btw... If you wire it with oversize wire and a corresponding rated breaker there is nothing that stops you from dialing back the max current it is allowed to draw by using the rotary dial. This then becomes the nameplate rating of the device and so you can scale back your load calculation numbers to fit as needed.

 

[eprosenx]

My house has a 125A circuit, and I was able to fit in a full 50A circuit for a 14-50 outlet. It all depends on your particular setup, what your load calculation looks like, how much you currently have used, etc. Load calculation is the main thing.

Yup exactly. It all has to do with loads as calculated using the NEC formulas (note that there are different requirements for new construction where they want you to build in lots of overhead for future use, vs. for remodel where you are allowed to use up that overhead that in theory they were required to build in when the house was built - assuming that was even a rule when your house was built...)

Note that I am not sure I have ever come across a 125a rated "service". Normally I hear of like 100, 200, or 320/400a services. I wonder if that is just a 100a service into a 125a rated panel (125a rated panels are common as 125a is the largest breaker often you can feed off of common panelboards that are upstream). Or maybe it is a 200a service into a 125a panel and 75a is just unusable due to the smaller panel rating?

As others have mentioned, one option is to do a 14-50 anyway and just crank back the charge amperage as needed manually, though this is NOT code compliant. You can't trust humans to always remember this and for Tesla to never accidentally reset it to the 32a max of the UMC Gen 2. I guess I should also call out that the UMC Gen 2 is only 32a (which means you calculate it as if it is a 40a load since it is "continuous". Even though you may deploy a 50a breaker and receptacle, you only have to factor in the 32/40a load. Then if you still don't have enough headroom in your load calc, as others have mentioned, you could do a 14-30, a 6-20, or even a 6-15 if absolutely necessary...

Though at that point, I am actually a huge fan of just installing a HPWC since you can then just crank up (limited by the wiring ampacity and breaker) or down the allowed current in pretty fine increments without swapping receptacle types, breaker sizes, and UMC adapters.

 

[Reid]

Breakers are cheap. ~$10-$20. Just install the #6 wire with a 50A breaker for the 14-50 then swap the 50A for a 60A when you get the HPWC.

I think as I was falling asleep, my brain reminded me what an obvious, stupid comment I made. I was thinking of oversizing wire/breaking for future expansion, and somehow neglected to realize... the entire purpose.. of a breaker

 

[flashflooder]

Hmm, perhaps I can get the code input of @eprosenx who's been reading NEC a lot. I was pretty sure it's forbidden to do the sheathed cable inside of conduit because you're double trapping the heat. If it's going to be trapped inside conduit with no air flow, I think that's why it needs the wires to be laid in there loose, instead of also having their heat trapped all next to each other inside the extra rubber sheath. There isn't cooling room if it's sheath + conduit.

It is perfectly acceptable to run sheathed cable inside conduit. I don't know where the contrary notion came from, but boy is it pervasive.

 

[nwdiver]

It is perfectly acceptable to run sheathed cable inside conduit. I don't know where the contrary notion came from, but boy is it pervasive.

I think it lowers the allowable ampacity...