I made my own dryer outlet to NEMA 6-20R connector

[gps1539]

Thought I'd post the following in case others are interested.

At home (California, US) I wired up a NEMA 6-20 outlet and use a 16 Amp Dostar for charging at home. However when we travel to family and charge at 110v we commonly needed the REX to fire up to get home. My brother in law is kind enough for us to charge there and gave the okay to use their 220v dryer outlet which should give us ample charge to get home without gas. I looked online for connectors and after some research I found it would be far cheaper to wire up my own.

Note. I am not responsible for any fires, or death if you follow this and do not understand electricity and risks involved

Plan
Buy Cable for Electric Dryer (in my case 3 pin) and NEMA 6-20R receptacle, then connect to two.

Parts:
- Generic 30-Amp, 3 Prong Dryer Cord
- Superior Electric YGA022F Straight Electrical Receptacle 3 Wire, 20 Amps, 250V, NEMA 6-20R

Note. My charger is 16 Amp. Ensure the cord and receptacle are rated higher than your charger.

Process (~ 10 mins)
1. Cut off the lugs/eyelets off the end of the Dryer cord
2. Strip back the insolation on the cord by 1/2 "
3. Connect the Neutral wire to the Neutral connector on the receptacle - use a multimeter to double check
4. Connect the 2 Live wires to the Live connectors - use a multimeter to double check

Test
1. Plug the dryer cord/receptacle in to an dryer outlet. - check that circuit breaker does trip, and cable does not get hot
2. Connect charger to receptacle. Check status of charger
3. Connect charger J1772 plug to car - check that circuit breaker does trip, and cable does not get hot

Cost
My Dryer cable was ~ $8.25 and receptacle was ~$7.99

Fits neatly in the frunk

 

[richs]

If I understand you correctly, you built a cable like this, right?

https://www.amazon.com/10-30P-T-Blade-adapter-3-Prong-Adapter/dp/B081NNSFZS

I guess that the ground wire of the 6-20R is wired directly to the neutral pin of the 10-30P?

Do you have a picture of your adapter?

 

[gps1539]

If I understand you correctly, you built a cable like this, right?

https://www.amazon.com/10-30P-T-Blade-adapter-3-Prong-Adapter/dp/B081NNSFZS

I guess that the ground wire of the 6-20R is wired directly to the neutral pin of the 10-30P?

Do you have a picture of your adapter?

Yes, very similar but at half the cost and mine is longer. Yes on the wiring, ground to neutral on the 10-30P.
I added a link to a photo.

 

[richs]

Yes, very similar but at half the cost and mine is longer. Yes on the wiring, ground to neutral on the 10-30P.
I added a link to a photo.

Thanks! I haven't done any electrical wiring, so I was confused as to whether ground can be wired to neutral in this way. I would have thought that your EVSE would give you a ground fault if you did that, but I guess it can't really tell the difference between neutral and true ground since the 6-20R doesn't have a neutral wire at all.

 

[jadnashuanh]

A GFCI works by comparing the current going out one lead and returning on the other. On a 120vac circuit, the neutral is one of the power leads, it's just referenced to ground at the panel. IN a normal circuit, the ground wire should NEVER see any current - it's there as a safety, not a current carrying conductor. A 240vac GFCI would also not use the ground connection, only looking at the current between L1 and L2...they must match like on the 120vac circuit between Lx and Neutral. ANy time it doesn't match, it must be finding a return path through ground, which might include you!

I think newer dryer plugs are required to be 4-terminal...i.e., to have a neutral and a ground in addition to the L1 and L2 hot leads, so if the place is newer, you'd need a 4-pin plug for your dryer. Stoves are in the same situation...if you've got an older install, you can bond the neutral and ground together, but all new installs require a 4-pin socket and plug.

 

[gps1539]

The 3 pin dryer plug 10-30P has no ground, just a neutral and they are no longer used in new houses as there is a 'small' risk of shock. Code is now 4 pin dryer sockets (Nema 14-30P). However most US houses (including mine), still use the 3 pin 10-30 sockets, which is what I created my cable for.

 

[jadnashuanh]

Some things in both a dryer and stove may use 120vac (in the stove, like the lights and maybe a receptacle). So, there's always the possibility of current in the neutral, even with a primarily 240vac device. Since there will always be some slight resistance between the ground and neutral away from the panel where they are connected, that opens the likelihood of a voltage potential on it...that's why new devices all come with a ground line as well so the case, which we hope is at ground potential, won't have any current running through it.

A 240vac EVSE doesn't use the neutral, but most want a ground for safety. But, they will not normally put any current through the neutral or a ground, if it exists. A GFCI will work just fine without a ground

 

[3pete]

Some things in both a dryer and stove may use 120vac (in the stove, like the lights and maybe a receptacle). So, there's always the possibility of current in the neutral

To put emphasis on it, this possibility means you should never use an adapter like this on a shared circuit. If you used your stove/dryer while your EVSE was plugged in on the same circuit, then your EVSE's "Ground" would be energized with the return current of the stove/dryer's 120v. Anything "Grounded" on your EVSE (metal case/ screws, etc.) would then be a shock (or worse) risk.

This is probably an unlikely scenario because most 240v appliances are on stand-alone circuits, but something to be aware of for anyone considering this approach.

 

[JohnWasser]

To put emphasis on it, this possibility means you should never use an adapter like this on a shared circuit.

Instead of connecting the NEMA 6/20R ground to the NEMA 10/30P neutral, you could wire it separately to a nearby electrical ground. That should be safe, or at least safer.

 

[robthebold]

Some things in both a dryer and stove may use 120vac (in the stove, like the lights and maybe a receptacle). So, there's always the possibility of current in the neutral

To put emphasis on it, this possibility means you should never use an adapter like this on a shared circuit. If you used your stove/dryer while your EVSE was plugged in on the same circuit, then your EVSE's "Ground" would be energized with the return current of the stove/dryer's 120v. Anything "Grounded" on your EVSE (metal case/ screws, etc.) would then be a shock (or worse) risk.

This is probably an unlikely scenario because most 240v appliances are on stand-alone circuits, but something to be aware of for anyone considering this approach.

If you've got the case of an appliance using neutral as a chassis ground and a single-leg load on that circuit, and a high Z on neutral due to whatever (bad connection, too small conductor, etc.) then you've got a ground fault electrocution hazard -- and not just on an EV plugged in to the same circuit, but on the appliance itself -- whether or not you've connected an EV charger in parallel.

 

[jadnashuanh]

Over the years, we've learned what's safe or not, and the codes have been adjusted to account to some of those 'what-if' situations. Luckily, they don't happen very often, but there's a definite reason why the code have been updated over the years...that's why things like a stove and dryer now require a 4-wire connection.

FWIW, the ground should NEVER have current on it in normal operations. It is there as an alternate path that can trip the breaker or blow the fuse should a fault occur. Current is NORMAL on a neutral, even though it is connected to ground at the panel.