US 50 Amp Industrial-Grade Car Charger Circuit

[wmras]

US 50 Amp Industrial-Grade Car Charger Circuit

Electrical fear started for me at 10 years old – an ungrounded bathroom light fixture wired hot threw me across the room into a bathtub. Since then, a 48-year electronic/electrical career had its share of shocks, burns, and explosions but good luck and caution prevailed. This garage project (all puns intended) will hopefully keep us and you safe and reduce the chance of ridiculously hot cables.

I recommend only safe, code compliant, charging adapters (never depend on a single computer to limit current – electrical spikes happen); larger circuit wires; and industrial grade connections. I have seen the effects of cheap equipment or poorly designed circuits. The pictures of lithium-battery cars still burning after 24 hours keep me cautious.

The charging circuit that follows is the solution for our garage. We have a 40-slot Siemens electrical panel with all slots filled. Thanks to Siemens, a 50A / 30A quad tandem circuit breaker was available that only used two slots. The two 30A slots for the dryer were replaced with the new breaker – two 30A breakers on the outside (for the existing dryer) and two 50A breakers in the middle (for the car charger). As a bonus, the electrician only had to add “car charger” between the previous “dryer” labels to relabel the panel.

Wire from the panel to the receptacle is 3 ea. #6-gauge THHN wires inside ¾” metallic conduit. THHN wire is rated for 90C temperature and for damp or dry applications. Metallic conduit lowers the temperature of the enclosed wire (compared to a sheath) and protects the surroundings from heat and potential electrical interference. Our circuit wire run is 8 feet of flexible metal conduit inside the walls plus 4 feet of rigid metal conduit. You can run up to 4 ea. #6-gauge THHN wires in ¾” metal conduit (3 for NEMA 6-50R and 4 for NEMA 14-50R receptacles). If your run is greater than 50 feet, strongly consider using #4-gauge THHN wire in 1” metal conduit (3 or 4 #4-gauge wires are ok in 1” metal conduit). 50A circuit breakers and receptacles will not accept larger than #4-gauge wire.

Hubbell 6-50R

Hubbell is my favorite receptacle brand: typically, one-piece low-resistance construction, strong, and tight grip but easy to use (good material and exact dimensions). Our circuit use a Hubbell 6-50R receptacle, chosen because the three-wire circuit reduces heat inside a conduit and is more flexible outside a conduit. The Porsche default 14-50P plug needs a 14-50R receptacle (which needs a four-wire circuit). Determine where you want your charger before you locate your receptacle. And most importantly, where do you want the ground pin: top or bottom? Our electrician left enough wire at the Hubbell 6-50 receptacle to disassemble and rotate the receptacle. With the Porsche Charging Dock (optional, not the Porsche Mobile Charger that comes with the Taycan), the ground pin must be at the bottom – the opposite of a normal installation.

NEMA 14-50R Receptacle (outlet) compatible with Porsche default US Supply Cable
(shown ground pin down for Porsche Charging Dock compatibility):

HBL9450A

by Hubbell Wiring Device-Kellems
Straight Blade Devices, Receptacles, RTP, Industrial Grade,
3-Pole 4-Wire Grounding, 50A 125/250V, 14-50R, Black

• Catalog number, ratings and certifications molded in face
• Sequenced contacts assure protection
• One-piece design power and ground contacts

Porsche NEMA 6-30 supply cable (our spare for emergency road kit)
This 30A supply cable is rated for 24A continuous current, but, if you look carefully, the cable tag is only rated for 16A – it may be a tag error or a lower current specified to minimize heat. (Note the 300 mm specified length is measured between the stress release moldings and the ground pin is far right, away from the end the cable, the normal ground pin location):

PARTS LIST SUMMARY

US 50 Amp Industrial-Grade Car Charger Circuit

Replace two 30 Amp breakers with:
SIEMENS Q23050CT2 Tandem Double Pole Circuit Breakers
30-Amp double pole outside
50-Amp double pole inside
Quadplex 1/2-Inch frame (two slots)
(or similar or two spare slots)

-------------------------------------
50 AMP, 240V NEMA 14-50 RECEPTACLE

For <50 ft from panel to receptacle:
#6-gauge THHN wire
Two hot wires + neutral + ground wire (4 total)
3/4" metallic conduit

For >50 ft from panel to receptacle:
#4-gauge THHN wire
Two hot wires + neutral + ground wire (4 total)
1" metallic conduit

Surface-mounted metal box with:
Hubbell 14-50R Receptacle, HBL9450A, UPC 783585015316

-------------------------------------
50 AMP, 240V NEMA 6-50 RECEPTACLE

For <50 ft from panel to receptacle:
#6-gauge THHN wire
Two hot wires + ground wire (3 total)
3/4" metallic conduit

For >50 ft from panel to receptacle:
#4-gauge THHN wire
Two hot wires + ground wire (3 total)
1" metallic conduit

Surface-mounted metal box with:
Hubbell 6-50R Receptacle, HBL9367, UPC 783585015279

-------------------------------------
The temperature ratings of the components in the circuits above are:
40C for the breaker
90C for the THHN wire
75C for Hubbell 14-50R & 6-50R receptacles (outlets or sockets)


Final recommendation: Hire a competent electrician - they are worth it.

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[daveo4EV]

nice install -it will give you years of servicing any EV you choose to charge.

 

[daveo4EV]

did you get the $0 25-foot charging cord option? it makes the charger placement far less critical if you have 25 ft of cord to deal with

my preferred install location for an EV charger is as close to the garage door as practical w/20-25ft cord - so that when necessary you have the flexibility to reach a car in the driveway to charge it.

 

[wmras]

did you get the $0 25-foot charging cord option? it makes the charger placement far less critical if you have 25 ft of cord to deal with

my preferred install location for an EV charger is as close to the garage door as practical w/20-25ft cord - so that when necessary you have the flexibility to reach a car in the driveway to charge it.

Smart, Dave! Yes, purchased the 25 ft. cord to reach a second future car in the garage. Your idea about the driveway also works. Thanks.

 

[wmras]

Finally received our Taycan Turbo S. It only took nine months after a confirmed allocation / commission number. Last night was the first charge at home.

For those of you familiar with the Porsche Mobile Connect Charger, you know I was anxious about the temperature rise in my industrial-grade electrical circuit. After charging for 2 1/2 hours In 83 degrees ambient at 40 amps, I checked the temperature of every element in the system from the circuit breaker to the J-1772 plug at the car.

Nothing was too hot for me to continuously hold but everything was warm. Surprises:
• Circuit breaker was remarkably cool
• NEMA 6-50 plug, receptacle, metal receptacle box, and metal conduit were all nearly the same temperature
• The infamous #10 gauge charger inlet wire was the hottest point, but not too hot to hold (implies <125-130F)

Bottom line, this industrial-grade circuit worked well, but note the Charger is in free-air, not inside an unventilated dock. It is also setting on a ladder because my drill left the building!

Edit 2020-08-28: corrected plug / receptacle from 6-30 to 6-50, corrected typos, deleted duplicate pictures

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