Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Successfully Converted 5-15 (15A/115V) to 6-15 (15A/240V)!

So rather than continue to highjack the CCS Adapter superthread here ("New" Sources of Tesla 'OEM,' Tesla-like, and/or Third-Party CCS1 Adapters), I figured I'd start a new thread.

Recall my charging situation is very limited. It'd cost an exorbitant amount of money/time to have a 14-50 wired up (long story on that one and I don't want to get into it here). Only available option was a "dedicated" 15A/115V (14AWG) circuit for the garage door opener, and another super shared 15A/115V circuit. So I've been using Level 1 15A/115V for the TMC with good results since I only use 6-7 kWh per day for my driving. Thanks to a few folks from the CCS superthread that suggested the 6-15, I found this thread on the 6-20 conversion: How I upgraded from NEMA 5-15 to NEMA 6-20 for $66 which helped immensely.

Only differences are that instead of converting to 12AWG, I kept the 14AWG for the 15A circuit but did the same swap in the circuit breaker using a tandem 15A and a double pole 15A. I have been using a nice Southwire Agripro 12AWG 12/3 extension cord for the Level 1 charger and wanted to keep using it for the 6-15, so I bought some Hubbell connectors as well as the Hubbell 6-15 receptacle based on some recommendations. They're made in USA (same with the extension cord) and cost 10x as much as the Chinese junk, but felt high quality.

I noticed that with Level 1 charging, it would always go 12A / 115V. With the 6-15 TMC adapter and everything hooked up, I see it go straight to 240V which is very nice.

Overall this was super easy and for other people with better home/condo/garage setups, it would be a real no-brainer. Thanks to everyone that suggested the 6-15 and explained it to me. Hopefully this helps others in the future when they do a search or are in a similar situation.
 

STS-134

Active Member
Aug 8, 2021
1,786
3,109
SF Bay Area
Only differences are that instead of converting to 12AWG, I kept the 14AWG for the 15A circuit but did the same swap in the circuit breaker using a tandem 15A and a double pole 15A. I have been using a nice Southwire Agripro 12AWG 12/3 extension cord for the Level 1 charger and wanted to keep using it for the 6-15, so I bought some Hubbell connectors as well as the Hubbell 6-15 receptacle based on some recommendations. They're made in USA (same with the extension cord) and cost 10x as much as the Chinese junk, but felt high quality.

I noticed that with Level 1 charging, it would always go 12A / 115V. With the 6-15 TMC adapter and everything hooked up, I see it go straight to 240V which is very nice.
So you're using a 6-15 to 5-15 adapter on one end of the cord and a 5-15 to 6-15 adapter on the other? That's the proper way to do it if you want to use the 5-15 cord.

I actually have a 14-50 extension cord that I barely ever use (would probably only use it if I were renting a house that had an outlet that wasn't in reach of the area I'm parking). I was thinking of getting 10-30/14-30 to 14-50 adapters for use on one end of the cord and 14-50 to 10-30/14-30 adapters for use on the other end. Then if the house has a dryer outlet that's out of reach of the garage, I would be able to use it and I'd effectively have an extension cord for any type of dryer outlet. Although I don't understand why 10-30/14-30 to 14-50 adapters are even allowed, as this would seem to be something that is against the electrical code. A "step-down" adapter, i.e. 14-50 to 14-30, should be allowed, but should be required to have a 30A breaker or fuse built into it (but none is actually made with one). Likewise, putting the "wrong" voltage into an extension cord seems like it should be against code too, because there's no guarantee that someone will use the proper adapter on the other end to convert back.
 
Last edited:
So you're using a 6-15 to 5-15 adapter on one end of the cord and a 5-15 to 6-15 adapter on the other? That's the proper way to do it if you want to use the 5-15 cord.

I have a Southwire Agripro 12/3 extension cord (that's 12AWG / 3 conductors) that's really good (I like how the insulation is designed for -58F to +210F so it remains flexible even when cold) and its made in the USA. So really it's like a 5-20 wire. I cut the ends off, and used Hubbell 6-15 connectors. I couldn't find any adapters I liked nor could I find any 6-15 extension cords I'd trust.
 
I have a Southwire Agripro 12/3 extension cord (that's 12AWG / 3 conductors) that's really good (I like how the insulation is designed for -58F to +210F so it remains flexible even when cold) and its made in the USA. So really it's like a 5-20 wire. I cut the ends off, and used Hubbell 6-15 connectors. I couldn't find any adapters I liked nor could I find any 6-15 extension cords I'd trust.
Great thinking. As long as it is the proper AWG and the insulation is rated for at least 300V, you're fine. People can also roll their own by using the proper gauge SO cable and appropriate connectors. The jacket and insulation of real SO or SJ cable is so nice, you'll never want to use stiff thermoplastic extension cords again.

Agreed that these "step-up/down" adapters are a terrible idea and are fires waiting to happen. There's a reason why there are different NEMA configurations.
 
Just wanted to do a sanity check...

The open circuit voltage at one of my other 240V outlets (electric stove, 14-50 outlet but on a 40A circuit) is 243V.

The voltage for my TMC 6-15 at 12A drops down to as low as 234V. Is this normal/safe? Or does it indicate any problems?
I experimented by dropping the charge current limit to 5A and still saw it drop to 237V-238V. At the full 12A for 6-15, it hovers 235-236V.
 

STS-134

Active Member
Aug 8, 2021
1,786
3,109
SF Bay Area
Just wanted to do a sanity check...

The open circuit voltage at one of my other 240V outlets (electric stove, 14-50 outlet but on a 40A circuit) is 243V.

The voltage for my TMC 6-15 at 12A drops down to as low as 234V. Is this normal/safe? Or does it indicate any problems?
I experimented by dropping the charge current limit to 5A and still saw it drop to 237V-238V. At the full 12A for 6-15, it hovers 235-236V.
I see around 243V OCV at my WC but when it's in use @ 48A, the voltage drops to around 237V. And that's with 4 gauge wiring (in theory, I could use 6 gauge, but I believe it would have to be THHN and in conduit or something like that, and I would expect a higher voltage sag with that type of wiring). Your wiring's rated for 15A and can safely carry 12A continuously.
 
I'd like to try this in my home, but it seems like no single outlet in the garage is on a dedicated breaker. All the outlets, including the one used for the garage door are tied to be the same breaker on my panel.

So this modification wouldn't be possible correct?
My garage basically had 2 circuits going in. One for the garage door opener, and the other for the ceiling lights (which is also part of my living room, exterior lights, etc etc). I extended the garage door opener wiring to use the same circuit as my ceiling lights/living room/etc... So this left my garage door opener circuit a dedicated 5-15. I verified the 14AWG wiring and that no other appliances/devices were attached to this circuit. My garage door opener doesn't use much current though, so I used a Kill-A-Watt to check the current draw during opening and closing to make sure it wouldn't trip my living room circuit before I moved it.

So if you have 1 circuit going to the entire garage (for the door opener, etc...) then it's not feasible as your EVSE/UMC will be drawing a constant 12A while charging!
 
Last edited:

STS-134

Active Member
Aug 8, 2021
1,786
3,109
SF Bay Area
So if you have 1 circuit going to the entire garage (for the door opener, etc...) then it's not feasible as your EVSE/UMC will be drawing a constant 12A while charging!
Unless everything on the existing circuit is drawing less than 6A. You could put in a step-down transformer and the 6A on the 120V side will become 3A on the 240V side, which maxes out the circuit. If it's on a 120V/20A circuit (code allows for multiple NEMA 5-15 outlets to be on a 20A circuit and this configuration is actually what is in my garage), then existing equipment could draw up to 16A (8A on the 240V side of a step-down transformer) and still have enough room for a EVSE to operate at 12A, assuming that nothing else on the circuit is a continuous load. But it's probably simpler to just run new wiring instead of installing a step-down transformer, and if you're going to do that, you might as well install a 14-50 outlet or HPWC. Oh, and if you install a step-down transformer you'd have to run a neutral anyway so...
 
So if you have 1 circuit going to the entire garage (for the door opener, etc...) then it's not feasible as your EVSE/UMC will be drawing a constant 12A while charging!

Yeah, that's what I believe I have. Well, I think it's on a 20A circuit since I see a 20A breaker in the breaker box. Which makes sense since I am able to draw 12A when charging on my 5-15 outlet, and still able to use the garage opener and stuff, without anything tripping. I have 5 outlets in the garage.

Oh well, I was hoping this would be a simple way to get some slightly faster charging.
 
Last edited:

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top