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NEMA 14-50 Supply cable heat data

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daveo4EV

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thanks for the update @KenU - I would "buy" the wrong gauge wire thing if the wire from the sub-panel to the NEMA 14-50 plug was also getting warm - my data for my setup shows that the _ONLY_ component that is suffering from an increase in temperatures is the Porsche NEMA 14-50 supply cable - there are essentially 4 segments to this system
  1. wire from the breaker to the NEMA 14-50 plug (and the breaker itself)
  2. Porsche supply cable to the PMCC
  3. PMCC itself
  4. Porsche J-1772 cable from the PMCC to the vehicle
surface temperature measurements in my case show the following for each segment

  1. 92F or less (including the breaker itself)
  2. 122F - 166F
  3. 94F or less
  4. 90F or less (including the J-1772 plug at the vehicle)
the _ONLY_ segment suffering any thermal stress is segment #2 - the Porsche Supply Cable.

after 5 hours charging @ 39.4 amps - temperatures are stable, consistent with the supply cable the only component offering any temperature deviation significantly above 90F (see segment #2 readings)

I'm not an electrical engineer and only have a DIY understanding of residential AC electrical systems, but my guess is the NEMA 14-50 supply cable from Porsche is the wrong gauge.
 
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NEMA 14-50 plugs are a 50 amp circuit (50 amp breaker) but need to be discounted 20% for "continuous" use devices like an EVSE…

NEMA 14-50 plugs are also allowed to be used with a 40 amp breaker which would require 32 amp max continuous Current draw.

40 amps is the correct current draw for a NEMA 14-50 circuit and exactly matches Porsche's charging specifications for the Taycan and their charger at 9,600 watts.

240 volts * 40 amps = 9,600 watts (240*40)
daveo4EV, I have 2 x Chargepoint chargers in my garage plug in versions on NEMA 6-50R plugs the breaker setup is 20/50 + 20/50 for each one I used to have a Tesla charger hard wired for my MS but added the second Chargepoint when we got he eTron. Should I change out one of the NEMA 6-50 to a NEMA 14-50 to charge the Taycan or just stay the way it is at 32amps?
 
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NEMA 6-50 is also rated for 50 amps (40 amps continuous EVSE usage) - the only difference is the 4th wire for the NEMA 14-50 which is _NOT_ used by any EVSE - the 4th wire in the NEMA 14-50 is a neutral wire so that RV's can use the NEMA 14-50 as a 120 volt circuit (Hot+Neutral+Ground) - for EVSE's I believe the NEMA 6-50 is preferred in that:
  • the 4th wire is not used
  • smaller conduit due to fewer wires in the wire run
  • lower cost (no un-necessary copper that is unused)
from a EVSE charging capacity point of view the NEMA 6-50 is identical to NEMA 14-50 assuming the following:
  1. 50 amp breaker
  2. wire gauge appropriate for 50 amp circuit
if the above two items are correct/building-code - you can support a 40 amp EVSE on a NEMA 6-50 circuit.

NEMA 14-50 is a 50 amp circuit with 4-pins - 2 hots, neutral, ground
NEMA 6-50 is a 50 amp circuit with 3-pins, 2 hots, ground

for an EVSE they are essentially electrically identical.

@SFEVER what model number are your Chargepoint chargers?
 

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NEMA 6-50 is also rated for 50 amps (40 amps continuous EVSE usage) - the only difference is the 4th wire for the NEMA 14-50 which is _NOT_ used by any EVSE - the 4th wire in the NEMA 14-50 is a neutral wire so that RV's can use the NEMA 14-50 as a 120 volt circuit (Hot+Neutral+Ground) - for EVSE's I believe the NEMA 6-50 is preferred in that:
  • the 4th wire is not used
  • smaller conduit due to fewer wires in the wire run
  • lower cost (no un-necessary copper that is unused)
from a EVSE charging capacity point of view the NEMA 6-50 is identical to NEMA 14-50 assuming the following:
  1. 50 amp breaker
  2. wire gauge appropriate for 50 amp circuit
if the above two items are correct/building-code - you can support a 40 amp EVSE on a NEMA 6-50 circuit.

NEMA 14-50 is a 50 amp circuit with 4-pins - 2 hots, neutral, ground
NEMA 6-50 is a 50 amp circuit with 3-pins, 2 hots, ground

for an EVSE they are essentially electrically identical.
OK so its the Chargepoint that's setting/limiting output to car at 32AMPS. The breaker is a pair 20/50 for each circuit ( from the Tesla charger) If I plug the Porsche charger into the 6-50 plug on a 20/50 circuit it will do 40AMPS is that correct
 
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If I plug the Porsche charger into the 6-50 plug on a 20/50 circuit it will do 40AMPS is that correct
yes that should be the case - and you will charge at a full 40 amps (9.6 kW)

ChargePoint makes a range of EVSE's that are 32 amp chargers but have NEMA 14-50/6-50 plugs - they are essentially underutilizing the 50 amp circuit, it's safe, effective, reduces costs and 90% of the time 32 amps vs. 40 amps make no difference.

your experience however highlight one of my pet-peeves with he EV charger industry

the industry has _NO_ standard for how they label their chargers.

depending on the manufacturer the "AMP rating in the model numbers either refers to the breaker that is required _OR_ the actual charge rate that will be achieve (requiring a bigger breaker)

example:

the ClipperCreek HCS-60 charger is a 48 amp charger, that requires a 60 amp breaker
32 amp ChargePoint chargers are 32 amp chargers that require a 40/50 amp breaker (50 amp only because it's more common configuration/installation - and there is no problem with having a breaker that is "too" big if a device isn't using the full capacity of the circuit - oversizing wire/breakers is NOT an issue, it's undersizing that is a problem (pulling 40 amps across wire only rated for 20 amps) - pulling 32 amps on wire rated for 50 amps is not an issue.

no consistency - so it's very very easy to get confused and many people do.

NEMA 6-50 will support a 40 amp charge rate (9.6 kW)

electrical code requires any device that is "continuous use" to derate the breaker by 20% - so 50 amp * 80% = 40 amps for continuous use.
 
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I also believe that this is further confused by the lack of a standard plug for a 40 amp circuit.

NEMA has many standard plugs for 30 amp circuits and…
NEMA has many standard plugs for 50 amp circuits

there however no North America "plug-type" for a 40 amp circuit - only 30 or 50…

you can however in most building codes use a NEMA 14-50 plug with a 40 amp breaker/wire - again as long as the device you are using respects the 40 amp limit (32 amp continuous load).

therefore there are some NEMA 14-50/6-50 installations that are not 50 amp circuits but really 40 amp circuits…

it for this reason that a lot of 32 amp chargers (EVSEs) have NEMA 14-50/6-50 plugs on them - it because it's the only plug type properly rated for > 30 amp loads, but it's "overkill" for a 32 amp EVSE …

causing further confusion.
 

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yes that should be the case - and you will charge at a full 40 amps (9.6 kW)

ChargePoint makes a range of EVSE's that are 32 amp chargers but have NEMA 14-50/6-50 plugs - they are essentially underutilizing the 50 amp circuit, it's safe, effective, reduces costs and 90% of the time 32 amps vs. 40 amps make no difference.

your experience however highlight one of my pet-peeves with he EV charger industry

the industry has _NO_ standard for how they label their chargers.

depending on the manufacturer the "AMP rating in the model numbers either refers to the breaker that is required _OR_ the actual charge rate that will be achieve (requiring a bigger breaker)

example:

the ClipperCreek HCS-60 charger is a 48 amp charger, that requires a 60 amp breaker
32 amp ChargePoint chargers are 32 amp chargers that require a 40/50 amp breaker (50 amp only because it's more common configuration/installation - and there is no problem with having a breaker that is "too" big if a device isn't using the full capacity of the circuit - oversizing wire/breakers is NOT an issue, it's undersizing that is a problem (pulling 40 amps across wire only rated for 20 amps) - pulling 32 amps on wire rated for 50 amps is not an issue.

no consistency - so it's very very easy to get confused and many people do.

NEMA 6-50 will support a 40 amp charge rate (9.6 kW)

electrical code requires any device that is "continuous use" to derate the breaker by 20% - so 50 amp * 80% = 40 amps for continuous use.
Yes my Chargepoint is a 32A model the one before the the NEW flex although that too is set to 32amps if you buy the plug version only the hard wired one can "FLEX"

Here is my breaker setup for the two chargers

fullsizeoutput_2de8.jpeg
 

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numbers are no higher at th 5 hour mark - so while they are high - things are stable - numbers are also no lower - I've measured the surface temperature of each "segment" of the system - and the only segment that is abnormally warm is the NEMA 14-50 supply cable - all other elements are 90F or less.
The cable is under 100C, and the charger hasn't shutdown from heat, so I'd not have any issues with that setup. Especially since it's in an enclosure to make sure nothing else is too close.
 

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I just install my dedicated 50A circuit. I used 6/3 wire (with a proper ground) MC wire with a total distance of about 90 ft. I used MC wire over NM because it can carry more current without heating due to the lack of dual insulation. Have been charging at 40A for about 2 hours and check the temps. The plug & outlet are running about 90F. The line side of the charger is about 99F. The cable going the Taycan is warm at the charger and the plug of the car; about 95F. Cable run from breaker panel to outlet is cool.

Thought I would post for others to compare.
 

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I got my car and charger back from the dealership but unfortunately my service tech left before I got there so I didn't get the dealer's temperature readings from the days the car was with them. They said they'll get it to me on Monday.

Before I brought my car in I took temperature readings at the plug, the top of the PMCC where the adapter cable comes out, and at my 50 amp circuit breaker. Here are my readings compared to @daveo4EV although I wasn't as comprehensive in logging my readings.. My temps are reflected in green (40 amp charging) and blue (32 amp charging). Most troubling to me is that my circuit breaker was 155F at its hottest point.

Temp Measurements Porsche Charger.png

Although dealer said Porsche's position is that car and charger are "operating within normal limits" at least I got the WLG2 software updates while it was there.

I'll take more readings next time I charge but next step is for me to get my electrician back out to redo wiring in my NEMA 14-50 receptacle to reduce amount of bends in wiring per dealer's electrician's recommendation..
 
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I've sent an eMail to my Sale Manager asking for Porsche's opinion on my data. Given the potential implications of such a letter - I do not expect a rapid response - but will share what ever they share with me.
Dave -

Thanks for the pictures and clear measurements.

My electrician installed a NEMA 14-50 receptacle with 6 gauge wire and a run of maybe 18 inches from breaker to plug.

Using a Thermapen Mk4 thermometer (better suited for meat of course) I am able to get a reading of 112º F on the head of the plug (compares to your reading of 144º F), 111º-114º F on the dongle cable from the plug to the Porsche Mobile Charger Connect, and 104º on the cable at the output of the PMCC of 99º F. Ambient room temperature was ~78º F. The PMCC is pulling 39.7 A at 220 V.

I am a little surprised that the temperature from the PMCC to the car is higher than your temperature and have no explanation. However, it seems the temperature range across the charging system in my garage is more consistent, ranging from 99º - 114º F.

Overall this range seems reasonable to me, and I agree with @KenU that you may want to check the gauge of the wire running from the power panel to the receptacle. When I saw the 6 gauge wire my electrician used I was surprised that it was really 4 bundles of copper as shown in the image below - very heavy duty.

Just for the record, this is NOT an application for the use of Aluminum wire - too dangerous.
6 Gauge Wire.png
 

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Dave -

Thanks for the pictures and clear measurements.

My electrician installed a NEMA 14-50 receptacle with 6 gauge wire and a run of maybe 18 inches from breaker to plug.

Using a Thermapen Mk4 thermometer (better suited for meat of course) I am able to get a reading of 112º F on the head of the plug (compares to your reading of 144º F), 111º-114º F on the dongle cable from the plug to the Porsche Mobile Charger Connect, and 104º on the cable at the output of the PMCC of 99º F. Ambient room temperature was ~78º F. The PMCC is pulling 39.7 A at 220 V.

I am a little surprised that the temperature from the PMCC to the car is higher than your temperature and have no explanation. However, it seems the temperature range across the charging system in my garage is more consistent, ranging from 99º - 114º F.

Overall this range seems reasonable to me, and I agree with @KenU that you may want to check the gauge of the wire running from the power panel to the receptacle. When I saw the 6 gauge wire my electrician used I was surprised that it was really 4 bundles of copper as shown in the image below - very heavy duty.

Just for the record, this is NOT an application for the use of Aluminum wire - too dangerous.
Nice installation.!
You have a short run with the correct wire size that is acting like a heat sink for the Porsche Supply Cable - remain suspicious this cable wire size is too small but have no proof yet (no Taycan and no 14-50 or 6-50 cable). Do have a 6-30 version that is #10AWG and suspect they are the same.
 

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So I checked my charger after just over 2 hours of charge this evening. The 14-50 plug on the Porsche power whip (the supply to the PMCC) was 134.9F! The power whip itself was 119F. Even the box containing the 14-50 receptacle was around 135F. I had the electrician who installed the setup for me come check it (he does commercial grade electrical work in data centers and major office buildings so he actually DOES know what he is doing). He did say that a continuous draw of 39+ amps (39.6 actually) will generate a lot of heat. Still........

My car is going to the dealer on Tuesday for the WLG2 update. I have been in touch with the local Porsche FTM and I think he will be there on Tuesday to check it out. He did suggest bringing the PMCC in as well to see if any data can be pulled from it.

Good thing a working EA station is within 15 miles of my house. I'll be charging there until this gets resolved!

Toby
 

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I'd expect stuff to get pretty toasty at 40A. I don't think I'd be too worried about stuff under 100C.
 

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Generally, I would agree. Only immediate issue I see is that the power whip for the PMCC shows a valid temperature range on its disclosure tag of a max of 122F. 139.4F is quite a bit outside of that range.
 

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