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HPWC on a 30A breaker?

DMack

Member
Jan 15, 2018
178
97
Oakland
I run a 14-30 on a 30A breaker in my garage, and I’m wondering if installing a HPWC on that breaker would be overkill, or if it’ll improve my charging rate.

I don’t mind using the 240/14-30 receptacle, but i have a referral reward to cash in on and I already got my nephew the Radio Flyer, lol.
 

nwdiver

Well-Known Member
Feb 17, 2013
7,985
10,343
United States
I run a 14-30 on a 30A breaker in my garage, and I’m wondering if installing a HPWC on that breaker would be overkill, or if it’ll improve my charging rate.

I personally don't think it's overkill. It's great to have a hard wired charging option for daily use. The HPWC is more durable than the UMC. Consult your electrician. If the wire is heavy enough and your service can support it you might be able to hard-wire the HPWC and upgrade to a 40A. Even with a 30A your charge rate will be sliiiightly faster due to lower line losses and slightly higher voltage at the car. Power = Current x Voltage.
 
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boaterva

Supporting Member
Apr 2, 2016
7,565
3,737
Northern Virginia, USA
You can set the HPWC to anything down to 12 amps. :D It’s just a way to have a hard wired connection and (if you get the 24 foot version, no extra cost now) a longer cord to perhaps reach to another car or out to the driveway. One reason I got the 24. (See link in sig.)
 
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TexasEV

Well-Known Member
Jun 5, 2013
7,646
8,479
Austin, TX
What’s the point? You’ll spend $500 plus installation and still charge at 24A. There is no reason to keep the UMC in the car. Leave it plugged in and hanging on the wall, and just unplug it and take it with you when you’re going out of town. That’s what tens of thousands of Model S owners with 14-50 outlets have done for the past 5 years, no reason for it to be different if you have a 14-30 outlet.
 
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bob_p

Active Member
Apr 5, 2012
3,691
2,804
We have both an HPWC (for our S 100D) and a 14-50 (for our S P85 which will soon be replaced by a Model 3).

Rather than installing a second HPWC, we purchased the 14-50 cable instead.

The HPWC and 14-50 are on different circuits.

The benefits of an HPWC:
  • Can be installed on circuits with higher power, up to 100A (assuming the car's onboard chargers can handle the extra power)
  • If two chargers are sharing the same circuit, two HPWCs can communicate to safely share power between the two cars
  • Smaller benefit - the HPWC can be set with internal switches to dial down the power usage below the circuit rating (if you have a 50A circuit, you can dial that down to 30A) - though you can also do this with the car's software.
Disadvantages of an HPWC:
  • Installation costs will be higher, because you need to run a conduit from the HPWC to the power panel, and then mount the HPWC on the wall.
  • If you move and want to remove the HPWC, you'll incur de-installation costs to dismount the HPWC and repair the exposed wall
 

davewill

Active Member
Feb 5, 2014
1,825
1,975
San Diego, CA, US
I run a 14-30 on a 30A breaker in my garage, and I’m wondering if installing a HPWC on that breaker would be overkill, or if it’ll improve my charging rate.

I don’t mind using the 240/14-30 receptacle, but i have a referral reward to cash in on and I already got my nephew the Radio Flyer, lol.
On the same breaker, no it will not improve your charging rate.
 
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Rocky_H

Well-Known Member
Feb 19, 2015
6,271
7,333
Boise, ID
Installation costs will be higher, because you need to run a conduit from the HPWC to the power panel, and then mount the HPWC on the wall.
If you're talking about the same size circuit, I think that conclusion is doubtful. Most of the labor is the same, with the conduit, etc. But with the wall connector, they get to use thinner, cheaper wire with one less conductor in it, so if it's a longer run, that could save some money on the materials cost.

I guess I should say that's how the electrician bidding should work. In reality, there is the "Tesla tax" factor, where if you are getting a wall connector put in, you can't hide the Tesla logo on the item you are getting installed, so the +50% may still show up on their estimate because they know you've got bucks, rather than if you just request "a 14-30 dryer outlet".
 

Yinn

Active Member
Nov 15, 2016
2,098
1,885
Behind you
I run a 14-30 on a 30A breaker in my garage, and I’m wondering if installing a HPWC on that breaker would be overkill, or if it’ll improve my charging rate.

I don’t mind using the 240/14-30 receptacle, but i have a referral reward to cash in on and I already got my nephew the Radio Flyer, lol.

You're getting a lot of half-opinions. Since you have the referral award, it would be irrelevant for all those who are citing a $500 cost for a HPWC. Your HPWC would be free.

Now once you have your HPWC, you can either install it onto your 14-30 or even have it hard wired to the existing breaker and wiring. But that do much and won't be able to increase your charging rate. At best, you get a shorter cord to manage.

If you were going to hire an electrian to install it anyway (or perhaps willing to try it yourself,) then it may very well cost you $500-$1000 to get it installed. But if you did that, it would be the right time to get that wiring updated to handle more amperage. In this case, yes there will be cost involved; but you will also be getting an improved charge rate.

If you went that route, your 14-30 is most likely giving you a charge rate of ~20mi/hr. Depending on what car you have, you will either have a 48amp charger or 72amp enabled charger. This could be a 70% improvement (48amp = 34mi/hr) or a 160% improvement (72amp = 52mi/hr) of your charging rate. Whether or not that cost is worth it...that depends on your situation and needs.

PS. Keep in mind you could also sell the HPWC or the Radio Flyer and make some money too..
 
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