Detached Garage, Conduit, 14-50, what else am I missing?

[kppolich]

Currently wall charging my model 3 on 120V 12A and looking to add a Nema 14-50 plug.

We are in Milwaukee, WI - 1950's house, detached garage ~40 feet away from main panel.
Main Panel: 100A Service
Garage: Load Center with (2) 15A circuits for receptacles & garage door opener.

Now, the previous home owners did us a favor and used 1.5" Schedule 40 conduit with the existing wire in it to the garage. There seems to be plenty of room to run a larger run for the EV Charger (14-50).


My Thoughts Are:
I'm hoping to run 6/3 in the existing conduit and put a 'Wye' 'Y' out of the conduit to the Nema 14-50 outlet and skip the garage load center all together while keeping the existing run in the other end of the 'y' to the load center.
32A Max charging would be fine, no plans on a wall charger in the future.

Concern:
Garage load center only has space for 2 breakers and I don't know if I

Questions:
6/3 or 8/3?

Can I run Romex, NM-B, or THHN in the existing conduit?

Is that 'Wye' allowed?

Do I need to use a 50A or 60A Breaker in the main panel?

Is a GFCI Breaker required?

 

[Sophias_dad]

Lets see... you need to do a load analysis to see if there's any chance whatsoever that you can support a 14-50. Keep in mind you really only need 32A continuous since the UMC will only do that.(That's a 40 amp circuit)

You are not allowed to run NMB(Romex) in conduit. You should use THWN(water resistant).

The wye should be allowed. Stick a junction box there.

The panel breaker should be 40 or 50 amps based on the wire you choose. Note that if you install a 6-50 you don't need a neutral through that conduit. Note that you must label the 14-50 with a clear '40 AMP' indication if you use 40 amp wire/breaker. I'm not positive if you are allowed to do that with a 6-50, but I would.

An EV outlet REQURES a GFCI breaker. You can avoid the expense of the GFCI and the outlet and the UMC adapter by using a HPWC instead of the UMC.

You don't mention the current wires running through the conduit to drive that subpanel, nor the diameter of the conduit, so I can't say if there's space for new wires.

I can tell you for sure it'll be a much cleaner install, and more likely to fit, if you just replace the wires feeding the subpanel IF needed(and you have the capacity!), and replace that subpanel.

Find out what the breaker/wires for that subpanel currently are. The garage door opener doesn't really count as a load(short lived and not much current) and unless you make a habit of running heaters or other large load items in the garage, you should be able to use basically 100%(discounted to 80% because its continuous) of that subpanel feeder breaker for a new EV charging circuit in the garage, completely avoiding new wiring.

 

[kppolich]

(1) 30A Breaker in main panel feeds (2) 15A circuits in the garage with what looks like 8ga wire.
That is the only wire running in the 1.5" conduit at the moment.

As for space in the main panel, there is an unused 50A in the main panel that used to power an electric range/oven.
I would replace that with a GFCI most likely.

 

[Sophias_dad]

(1) 30A Breaker in main panel feeds (2) 15A circuits in the garage with what looks like 8ga wire.
That is the only wire running in the 1.5" conduit at the moment.

As for space in the main panel, there is an unused 50A in the main panel that used to power an electric range/oven.
I would replace that with a GFCI most likely.

So save all the trouble and put a 240v 30 amp HPWC hanging off a new panel in the garage. You'll have 24amp continuous instead of 32 amp charging, and you'll avoid running new wires, a new GFCI/Outlet/adapter/UMC.

But yeah, if you really want to go down the 14-50 route, 8 gauge would be fine for a 50 amp breaker. You might have trouble finding a junction box that'll take 1.5" conduit, I've never looked for them myself. At the same time, those three conductors(plus ground which needs to be 10 gauge at least could just as well be used for a new subpanel, and you could STILL hang a 50 amp 14-50 off that subpanel.

Note that if you use NMB for a 50 amp circuit, it has to be 6 gauge. That might apply once you are in the garage, but you aren't supposed to have unprotected NMB in a garage anyway.

 

[Gauss Guzzler]

With a 30A breaker feeding that subpanel it's a fair assumption that it's 240V and 10AWG.
In that case the cheapest/easiest approach would be to swap that little 2-circuit subpanel for a 4+ space unit. That'll run you maybe $40 or $50 and then you can drop in a 30A breaker ($15) to feed a wall charger.

And if you find/forsee that 30A is not enough for everything you want, use your old 10 gauge wires to pull some new 6ga thru that nice roomy conduit and bump it all up to 60A.

Or if you want the charger somewhere else and/or don't want to redo that subpanel, and you have enough space in your main panel, then yes, you can put a Tee in that conduit and pull a dedicated circuit thru direct to your charger.

Don't mess with 14-50's unless you have some special circumstances. The wall charger is almost always the better option.

 

[kppolich]

Thanks for the info.
My only hesitation on not dong the HPWC is that we will likely only be in this house for 1-2 more years.

 

[Gauss Guzzler]

It’s easy enough to just unscrew the wall charger and take it with you when you move. Slap a blank plate over the hole and mark it as “60A EV Circuit”

Or just leave it. A 2-year old charger is only worth a few hundred dollars, but may increase the home value by much more.

 

[davewill]

If that's 8ga THHN that's already running out to the garage, he could switch to a 40a breaker, replace the load center he has with a bigger panel and do a 30a (14-30) or 40a (14-50) circuit. However, I think I'd do what he originally suggested, pull some 6ga THHN, and either hook up a 14-50, or go ahead and do a wall connector.

 

[kppolich]

Hi Dave,
To halfway wrap this up-- I ordered 52 feet of 6awg TNNH and 52 feet of 10ga ground to go with my 50A GFCI breaker I got a screaming deal on as well...

I figured that gives me a few options, all future proof.

Option A: Run the 6a to a new sub panel in the garage and place the 50A GFCI breaker in the new sub panel and have a nice short run of 6ga to the new 14-50 outlet. Will need to source a new sub-panel as well with additional breaker slots.

Option B: Run the 6ga in addition to the existing 10ga in the conduit to power a dedicated 14-50 outlet by skipping the exiting 2 bay sub panel with a Y.
Is it allowed to run wire in and of Sub Panel like a junction box and not connect it to a breaker?

Option C: Use the 6ga run from the main panel to the new sub panel in the garage with likely 4-6 slots for a future 60A breaker (non gfci) for a HPWC.

Either way, in a few days I'll have 6GA run to the garage and I'm leaning towards option A at the moment but still need to source a

However, I have been thinking about selling my extra mobile charger kit (~200), 50A GFCI outlet) and NEMA plug for another $100 and put $100 or so more into a HPWC in option C.

Just waiting to find a decent deal on a HPWC somewhere.

-KP

 

[MN-MS100D]

Running power to detached structures invokes many more NEC requirements, and they are complex. Rules are different for feeders than branch circuits. Grounding and bonding rules are different. Merely changing what you have in the pipe now might eliminate some conditions that were "grandfathered in" if you would have left them as-is. Seek a Master Electrician before proceeding. Your #10 "ground" might not be sized correctly if it needs to be sized as a service ground vs. an equipment grounding conductor. Is there a ground rod? Detached structures need disconnecting means. The list goes on. Load calcs? Running more than 3 current carrying conductors in pipe required derating. etc. Sorry.

 

[ATPMSD]

You are not allowed to run NMB(Romex) in conduit

I don’t think this is always true. Found this:

“The only time you can run romex in conduit is when you are dropping it from a protected area to a non-protected area.” Such as from the top of a ceiling down an interior wall to an outlet.

?

 

[Sophias_dad]

I don’t think this is always true. Found this:

“The only time you can run romex in conduit is when you are dropping it from a protected area to a non-protected area.” Such as from the top of a ceiling down an interior wall to an outlet.

?

Yes, that's my understanding, I didn't want to pollute the issue.

 

[kppolich]

Well I can tell you this, whoever installed the existing sub panel in the detached garage ran Romex from our basement, underground in schedule 40 conduit to our garage.

If Romex in conduit to a detached garage is a no-no then that's even more reason for me to pull it out and put in the bigger THHN/new sub panel.

They also ran a piggyback wire back to the house to control a switch for an outside garage light that I can now remove as the outlet was rewired to be always on/motion light installed.

 

[ATPMSD]

Yes, that's my understanding, I didn't want to pollute the issue.

I understand and thank you. Just trying to make sure I did not miss something.

 

[Sophias_dad]

If Romex in conduit to a detached garage is a no-no then that's even more reason for me to pull it out and put in the bigger THHN/new sub panel.

You got it. Just go to #6 or #4 THWN (not just THHN I think, since its not meant for underground/wet areas, maybe not even garages) put in a proper subpanel and work from there. Most THHN is also THWN rated.

Brush up on the neutral/ground requirements for a subpanel. Unlike a main, the neutral and grounds are not supposed to be tied in the subpanel. It looks like you are fine in that regard, in that the ground seems to be connected to the subpanel case and I >assume< the conduit leaving the panel is acting as a ground on the other end(for the circuits being fed)

 

[Gauss Guzzler]

So 10/3 NM is usually orange, and 8/3 NM is usually stranded. So I’m guessing you have 10/3 UF which is intended for direct burial, and this might change everything.

 

[Sophias_dad]

So 10/3 NM is usually orange, and 8/3 NM is usually stranded. So I’m guessing you have 10/3 UF which is intended for direct burial, and this might change everything.

Indeed... I wonder if that's actually in conduit the entire distance, or if the conduit just runs down into the ground, transitioning to direct burial for the rest.

 

[davewill]

Indeed... I wonder if that's actually in conduit the entire distance, or if the conduit just runs down into the ground, transitioning to direct burial for the rest.

He'll find out pretty quickly when he tries to pull the wire!

 

[Eric33432]

I am curious what you ended up doing?

Here are some things to consider:

Your main service is only 100 amps, you should do a load calculation to see if you can add another 24/32/40/48 amps of 240 volt load. You can use an app called Mike Holt's Electrical Toolbox to do that.

Since it is in a detached building, if this was installed today it would need its own ground rod. You might be grandfathered. If you upgrade the wire you should install a ground rod if one is not already installed.

If you run new wire be sure it is rated THWN. THWN is good for wet locations. Most wire today that is stamped with THHN is also rated THWN, but you need to check. You cannot run THHN in conduit underground as it is considered a wet location. If you go with option A and feed the sub panel with the new #6 wires, you will need to run 4 wires, not 3. You can run 3 #6 copper THWN for the 2 hots and neutral, and a #10 copper ground. If you do this, here's hoping it is in conduit all the way back to the house!

To avoid complication, I would go with your option A. This would avoid derating for more than three current carrying wires, conduit fill etc. But if you did go with option B, I would pull 4 new #10 conductors to feed the existing sub panel (from 30 amp breaker) along with two #6 and one #10 for the 6-50 outlet, all copper.

But. . . . .

If you find you might overload your 100 amp service, or you just want to save some money, time, and work, and you have the opportunity to charge from evening to morning most days, I would see if there is a tandem breaker like this that would fit into your existing panel. This will give you 24 amps, or about 5.5 kW which might be enough.

You would jut leave the existing #10 cable 30 amp feeder in place. The wire coming in looks like it is UF cable, which should be OK in wet locations. If you determine if it is UF cable all the way to the main panel, or at least in the section that is in the underground part of the circuit it should be OK to continue using that.

As previously stated by others, unless you are running some big continuous load in the garage like a heater, you can ignore the loads on the 15 amp breakers if they are just 1) garage door opener, 2) some receptacles in the garage that are only occasionally used.

You will have to install a Tesla Wall Connector since such a breaker would not be a GFCI breaker but you can use all the money you save to buy a Tesla Wall Connector.

 

[kppolich]

Apologies for the delay, we've had a few snow storms and I haven't got around to pulling the wire yet.
As of now I have the 6ga Wire, 50A GFCI breaker, and Hubbell 14-50 outlet waiting for a nice warm spring day to be installed.