What makes a continuous load outlet so expensive? If they were mass produced couldn't they be pretty much the same price?
Don't use a $5 range outlet for EV charging
21–30 of 35 posts
Re: Don't use a $5 range outlet for EV charging
#22[deleted]
Re: Don't use a $5 range outlet for EV charging
#23I hope I'm not too jaded, but this reads really weird to me. The author disses a "$5 range outlet" (even though I don't think they're usually that cheap), then talks about spending several hundred bucks on better outlets for "evaluation"... and the evaluation never comes. We just get a paragraph of innuendo without any real-world testing or even a thorough teardown. Do the plugs have any real-world design flaws, or i…
> Do the plugs have any real-world design flaws, or is this just gear snobbery?
Design flaws? No. Limitations, yes.
A $5 NEMA 14-50R is designed for maybe a few dozen to a few hundred insertion cycles. They’re typically used for ranges (and other fixed equipment) that are plugged in once, and then unplugged once more when you replace the appliance. When the contacts wear out, gaps appear and arcs occur inside the device and it melts. Internal shorts can also happen inside the device. Here’s a tear down video of a residential NEMA 5-15R and a commercial NEMA 5-15R that illustrates some of the shortcomings of cheap wiring devices and shows how more expensive devices have a more robust design: https://youtu.be/kX6xnOksQTc
It could also be caused by not using a torque screwdriver to tighten the terminal screws, which is required by the NEC. You must tighten the terminal screws to the torque value listed in the wiring device instructions, and hold it there for 5 seconds. A loose termination can cause all sorts of nasty problems.
There are many grades of wiring devices meant for different applications. More $$ = more durable, better contacts, a full brass strap inside the device, etc.
Most people are unaware that multiple grades of wiring devices exist, and also unaware that it can be very important to use the correct one and also install it correctly which requires a torque screwdriver. This is why it’s a good idea to just pay an electrician to do it correctly.
Leviton sells a heavy duty NEMA 14-50R specifically designed for plug in EV chargers that are designed to handle many insertion cycles. It costs about $67, but that’s the wiring device you buy if you’re going to be doing a lot of insertion cycles.
https://store.leviton.com/products/50-amp-ev-charging-recept...
There’s no such thing as a NEMA 14-50R that isn’t rated for a 50A continuous load. It wouldn’t be UL listed if that was the case.
Re: Don't use a $5 range outlet for EV charging
#24I worked at an EV charger manufacturer. This is a known issue. The issue is a 240V plug value engineered for non-continuous use for things like cooking and laundry loads (where amperage spikes but levels off at fairly low amps) versus a continuous 7-10 hour load like an EV/EVSE (where you have high amps continuously and lots of resulting heat transfer). It's limited to home EV charging. This is one reason why given t…
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Re: Don't use a $5 range outlet for EV charging
#25> Even though the 14-50R outlet is technically a 50A outlet, when used as a kitchen range plug, they are often wired on a 40A circuit. This is permitted by the Canadian Electrical Code rule 26-744 5). I wonder if the US National Electric Code allows this.
Yes, but only for circuits with multiple outlets, an individual branch circuit must use a wiring device not less than the ampacity of the branch circuit.
You are allowed to use 40A and 50A receptacles on a multi-outlet 40A circuit. You’re also allowed to use 15A and 20A receptacles on a multi-outlet 20A circuit.
Table 210.21(B)(3) of the NEC
Re: Don't use a $5 range outlet for EV charging
#26I hope I'm not too jaded, but this reads really weird to me. The author disses a "$5 range outlet" (even though I don't think they're usually that cheap), then talks about spending several hundred bucks on better outlets for "evaluation"... and the evaluation never comes. We just get a paragraph of innuendo without any real-world testing or even a thorough teardown. Do the plugs have any real-world design flaws, or i…
> Do the plugs have any real-world design flaws, or is this just gear snobbery? Design flaws? No. Limitations, yes. A $5 NEMA 14-50R is designed for maybe a few dozen to a few hundred insertion cycles. They’re typically used for ranges (and other fixed equipment) that are plugged in once, and then unplugged once more when you replace the appliance. When the contacts wear out, gaps appear and arcs occur inside the dev…
Premise challenge: I’ve plugged my EV charger in… three times, maybe? The high cycle part is the connection to the car. The connection to the outlet stays plugged in for literally years at a time.
Probably some people have abnormal use patterns that have them moving a 220v charger around all the time, but I’d bet it’s highly unusual amongst EV owners who charge at home regularly.
Re: Don't use a $5 range outlet for EV charging
#27I need to see evidence of this "overheating and melting the outlet". Electrical code requires downrating of actual capacity to prevent things like this. You're far more likely to see damage due to loose connections - either the wires are not fully secured to the outlet, or the plug is not fully seated & snug, both of which cause overheating.
Read any EV forum. Plenty of people with melted Leviton 14-50 outlets, despite having fully secure and tightened wires.
Fully secured and tightened isn’t good enough. Per code, you need to use a torque screwdriver (or other approved means) to tighten the terminal screws to the torque value listed in the wiring device instructions.
> NEC 110.14 (D)
Tightening torque values for terminal connections shall be as indicated on equipment or in installation instructions provided by the manufacturer. An approved means shall be used to achieve the indicated torque value.
Re: Don't use a $5 range outlet for EV charging
#28Earlier quoted context omitted.
The “50” in 14-50R refers to the maximum "rated" amperage allowed through the receptacle. Load-wise, to avoid melted connector, you don't plug something with load capacity of more than 37-ish ampere thru this 14-50R receptacle. The OP is confusing load rating vs. capacity rating. However, computed loads are always adequately under the breaker size, and beneath wire capacity, and below the receptacle rating, all three…
What's your math on this? I don't understand how you're getting to 37A. A 50 amp rated outlet (backed by a 50 amp rated breaker, and wire capable of handling 50 amps) is fully NEC compliant if you run it for 40 amps continuously (80% derating) or 50 amps temporarily (which NEC defines as a load expected to continue for 3 hours or more). EV chargers fall under the 80% derating. I'm not aware of any EV charger that use…
> What's your math on this? I don't understand how you're getting to 37A
You have to derate conductors installed in ambient temperatures greater than 86F. I would definitely use NM-B 6/2G (or 6/2G MC cable) for a NEMA 14-50R in a garage, just to account for derating since you get to start at 75A for #6 rated for 90C.
The first derating factor is .94 for ambient temps between 87-95F, .94 times 40A is 37.6A if you use the 75C column. I think NM cable is rated for 90C, so if you derate #8 from 55A at .67 to account for a much higher temp of 120-130F, you get 36.85A.
310.15 (B)(1)
Ambient Temperature Correction Factors Based on 30°C (86°F)
For ambient temperatures other than 30°C (86°F), multiply the allowable ampacities specified in the ampacity tables by the appropriate correction factor shown below.
Re: Don't use a $5 range outlet for EV charging
#29Earlier quoted context omitted.
Read any EV forum. Plenty of people with melted Leviton 14-50 outlets, despite having fully secure and tightened wires.
Fully secured and tightened isn’t good enough. Per code, you need to use a torque screwdriver (or other approved means) to tighten the terminal screws to the torque value listed in the wiring device instructions. > NEC 110.14 (D) Tightening torque values for terminal connections shall be as indicated on equipment or in installation instructions provided by the manufacturer. An approved means shall be used to achieve…
I can assure you this often has nothing to do with torque. The Leviton outlet lists a torque of 40 inch pounds. You can hand tighten much tighter than that relatively easy with a reasonable screw driver.
There’s some instances of undertorqued outlets, sure, but that isn’t the predominant factor here. The crap outlets are the issue.
Re: Don't use a $5 range outlet for EV charging
#30Earlier quoted context omitted.
Fully secured and tightened isn’t good enough. Per code, you need to use a torque screwdriver (or other approved means) to tighten the terminal screws to the torque value listed in the wiring device instructions. > NEC 110.14 (D) Tightening torque values for terminal connections shall be as indicated on equipment or in installation instructions provided by the manufacturer. An approved means shall be used to achieve…
I can assure you this often has nothing to do with torque. The Leviton outlet lists a torque of 40 inch pounds. You can hand tighten much tighter than that relatively easy with a reasonable screw driver. There’s some instances of undertorqued outlets, sure, but that isn’t the predominant factor here. The crap outlets are the issue.
True, you can easily hand tighten to 40 inch pounds.
After looking at some more evidence, I agree that it’s probably just a poorly designed receptacle, probably on par with a residential 5-15R which are made to a much lower standard than a comparable commercial 5-15R.
It looks like Leviton may have discontinued the receptacle that lots of people had melt on them so that probably is the case.