NEMA 14-50 Supply cable heat data

Toby Pennycuff

Well-Known Member
First Name
Toby
Joined
Jun 12, 2019
Threads
5
Messages
172
Reaction score
204
Location
Dallas, TX
Vehicles
Porsche 911S, Porsche 930, Porsche GT3 Cup, Taycan 4S
Country flag
After having my car updated with the WLG2 update yesterday, I understand that my dealer is opening an internal support ticket with PCNA regarding the heating situation with the 40-amp power whip. If I hear any more detail, I will provide that data here in this thread.

Toby
Sponsored

 

mike-taycan

Well-Known Member
First Name
Mike
Joined
Jul 24, 2020
Threads
7
Messages
51
Reaction score
26
Location
US
Vehicles
Taycan
Country flag
Finally, the suspected heat culprit in the Porsche Mobile Charge Connect (PMCC) has been confirmed. The 14-50 input supply cable (photo below) is 10AWG (American Wire Gauge), the normal US electrical code size for a 30 amp circuit, not a 50 amp circuit. However, this cable is rated for 105C, much higher than most cables, and is a component of a system, not part of an external electrical circuit - different rules apply. The same cable is used on the 6-30 input supply cable in my possession. A #10-gauge wire can conduct 40 amps, but it will heat to ~90C (194F) at 20C (68F) ambient.
I am not an electrical and it might be good to get an electrical engineer to comment. Not all 10AWG cables are made the same and have different properties. Solid, stranded, insulation, conduit types make a big difference on the amount of amps vs heat generated.
 

mike-taycan

Well-Known Member
First Name
Mike
Joined
Jul 24, 2020
Threads
7
Messages
51
Reaction score
26
Location
US
Vehicles
Taycan
Country flag
A #10-gauge wire can conduct 40 amps, but it will heat to ~90C (194F) at 20C (68F) ambient.
Would you mind providing where you got this. I think that might be the rating of the insulation on the wire (90C/194F). Different wire insulation is rated to different temperatures (60/75/90C) and that does not mean it will be that temperature at max amps.
 

evanevery

Well-Known Member
First Name
Ed
Joined
Sep 10, 2019
Threads
38
Messages
997
Reaction score
1,131
Location
Wisconsin
Vehicles
2020 Taycan Turbo S, 2019 BMW i8, 2023 BMW iXM60
Country flag
The extra pin on the 14-50 is for a neutral wire, so you can get 120V out of the socket too. EVSEs don't use it. My EVSE came with a 6-50 plug. It's a ChargePoint 32A charger.

To go from 14-50 to 6-50 an adapter just drops the neutral wire, which means you get 240V only.
I know what the 4th pin is for. I just think its reckless to claim that NONE of the "4-pin" chargers use it...

You will also note that it is very rare to find a 6-50P (3-Pin) PLUG to 14-50R (4-pin) SOCKET adapter because no electrician is going to tell you its OK to simply ignore the neutral on the appliance plug. If you find one, its going to come with a lot of legal disclaimers (I've seen "Only for use with Tesla Charger", etc).
 
Last edited:

mike-taycan

Well-Known Member
First Name
Mike
Joined
Jul 24, 2020
Threads
7
Messages
51
Reaction score
26
Location
US
Vehicles
Taycan
Country flag
I looked up the specs on the wire and came across whip ratings from the manufacture of my cable. http://www.yung-li.com.tw/EN/Products/heavyduty_nema.htm

The 4-50P whip with 10 AWG wire is rated to 30A 125V/250V. Not sure this exactly the same cable used but is probably close. Maybe the short run of the whip allows more amps?
 


KenU

Well-Known Member
Joined
Feb 1, 2020
Threads
1
Messages
78
Reaction score
53
Location
Altair IV
Vehicles
Too many to list
Country flag
KenU,

The part number for the "power whip" that connects the PMCC to a 40-Amp power supply is 7PP-971-678-ED. In Porsche "parlance" the part is called "Charge cable for mains socket".

Be aware that this supply cable is built from 10AWG wiring, which many here in this thread (me included) are questioning.

Toby
Thanks, Toby. I think I already have that plug/cable. I'm searching for the correct 14-50 supply cable that's rated for a 50 amp circuit, not 30A as Bill expertly reported here as the cause of many of us with abnormally hot supply cables.
 

ron_b

Well-Known Member
First Name
Ron
Joined
Dec 30, 2019
Threads
327
Messages
1,587
Reaction score
1,677
Location
SF Bay Area, USA
Vehicles
2020 Taycan 4S
Country flag


Vim Schrotnock

Well-Known Member
First Name
Vim
Joined
Oct 20, 2018
Threads
23
Messages
1,005
Reaction score
1,459
Location
Cincinnati
Vehicles
GTB1 Race Cayman, Taycan Turbo S
Country flag
There is simply no way that the Porsche engineers would make such a simple and basic mistake as to supply a wire gage AND INSULATOR that is not rated for their application. 10 gage copper wire is rated for 40 amps with the proper insulation:

10-gauge solid copper wire in general has a resistance of almost exactly 1 ohm per 1000 feet. The rating is limited by how much heat the insulation was designed to withstand. NEC 60/75/90 deg C rated insulated wire is rated for 30/35/40 amps respectfully. From this information, you can figure out the maximum length of wire that is safe to use for a particular voltage and load. Or, you can calculate the maximum load for a particular voltage and wire length. Or max voltage for known load and length.
 

KenU

Well-Known Member
Joined
Feb 1, 2020
Threads
1
Messages
78
Reaction score
53
Location
Altair IV
Vehicles
Too many to list
Country flag
There is simply no way that the Porsche engineers would make such a simple and basic mistake as to supply a wire gage AND INSULATOR that is not rated for their application. 10 gage copper wire is rated for 40 amps with the proper insulation:

10-gauge solid copper wire in general has a resistance of almost exactly 1 ohm per 1000 feet. The rating is limited by how much heat the insulation was designed to withstand. NEC 60/75/90 deg C rated insulated wire is rated for 30/35/40 amps respectfully. From this information, you can figure out the maximum length of wire that is safe to use for a particular voltage and load. Or, you can calculate the maximum load for a particular voltage and wire length. Or max voltage for known load and length.
Not sure about that Vim.

My original PMCC came with the 30A plug/cable. Had my electrician put in a 50 Amp breaker along with a 6 gauge wire (changing to 4 gauge tomorrow) and voila, that supply cable couldn't be held for more the 3 seconds after 90 minutes of charging. Now have the correct, or what I thought was correct prior to Bill's post, 14-50 plug/supply cable and it's still ridiculously hot at 40A. Dialed down to 24A and not quite as hot but still above warm, for sure. My dealer told me early on that Porsche gave them the 30A plug and that's what it was supposed to be. Apparently, they were wrong. All they (Porsche, not the dealer) had to do was look in the Manual and see "14-50 supplied" plug/cable. Dealer was just going by what corporate was supplying and advising.
 

mike-taycan

Well-Known Member
First Name
Mike
Joined
Jul 24, 2020
Threads
7
Messages
51
Reaction score
26
Location
US
Vehicles
Taycan
Country flag
There is simply no way that the Porsche engineers would make such a simple and basic mistake as to supply a wire gage AND INSULATOR that is not rated for their application. 10 gage copper wire is rated for 40 amps with the proper insulation:
I think I agree with this. Given the shortness of the cable, I think it can probably handle the 40A. It will get warm, which shouldn’t be a problem.

My original PMCC came with the 30A plug/cable. Had my electrician put in a 50 Amp breaker along with a 6 gauge wire (changing to 4 gauge tomorrow) and voila, that supply cable couldn't be held for more the 3 seconds after 90 minutes of charging. Now have the correct, or what I thought was correct prior to Bill's post, 14-50 plug/supply cable and it's still ridiculously hot at 40A. Dialed down to 24A and not quite as hot but still above warm, for sure. My dealer told me early on that Porsche gave them the 30A plug and that's what it was supposed to be. Apparently, they were wrong. All they (Porsche, not the dealer) had to do was look in the Manual and see "14-50 supplied" plug/cable. Dealer was just going by what corporate was supplying and advising
Will be interesting what Porsche says. I have 6/3 wire in MC running 90 ft, 14-50R running and run at 40A all day long. The wire is cool to touch, the plug and whip to charger is warm, end of cable that connects to the car is warm but nothing “hot”.
 

r553

Well-Known Member
First Name
Rob
Joined
Apr 26, 2019
Threads
7
Messages
421
Reaction score
201
Location
Rockledge FL
Vehicles
981 Spyder, 2015 Cayenne Diesel, 2020 Taycan 4s
Country flag
I wonder if this cable heating contributed to the Taycan/garage fire in Florida. There was not much left to analyze.
 

HelfFL

Well-Known Member
Joined
Sep 6, 2019
Threads
17
Messages
236
Reaction score
238
Location
FL
Vehicles
'20 Taycan Turbo
Country flag
If it was just warm then I probably wouldn't be concerned but as @KenU experienced (and I am experiencing the same), at 40 amps the cable is hot to the touch and in my case, my circuit breaker is way too hot after just an hour or so of charging at 40 amps.

The fact that many of us are experiencing this issue and in several cases having breakers trip or charging sessions stopped due to overload, something has to be figured out. Since many of us have different wiring setups installed for our chargers, the only common thing among us is the PMCC itself. So we just have to figure out the cause so we can get it taken care of.
 
Last edited:

KenU

Well-Known Member
Joined
Feb 1, 2020
Threads
1
Messages
78
Reaction score
53
Location
Altair IV
Vehicles
Too many to list
Country flag
I think I agree with this. Given the shortness of the cable, I think it can probably handle the 40A. It will get warm, which shouldn’t be a problem.



Will be interesting what Porsche says. I have 6/3 wire in MC running 90 ft, 14-50R running and run at 40A all day long. The wire is cool to touch, the plug and whip to charger is warm, end of cable that connects to the car is warm but nothing “hot”.
What is 6/3 wire? 6 gauge and something else. MC I assume is metal casing. Keep in mind I can just about turn on a light switch, that's my advanced knowledge of all things electrical!
 
OP
OP
daveo4EV

daveo4EV

Well-Known Member
First Name
David
Joined
Jan 28, 2019
Threads
160
Messages
5,793
Reaction score
8,599
Location
Santa Cruz
Vehicles
Cayenne Hybrid, 911(s) GT3/Convertable
Country flag
6 is gauge of wire
3 is number of conductors
Sponsored

 
 




Top