Backstabbing 15a receptacles and switches

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
The POCO metering device generally uses CT's at the service entrance point to measure how much $$ is passing through, the greater the voltage drop at the point of use, the more current the device uses (generally, but not always) to achieve its rated output. Ever notice a motor that has a two amperage ratings, one for 230V and and one for 208V? The same is true for most loads, as voltage drops, current goes up, not to mention incidental heating of the structure, something we don't need in the south!.
I must disagree with that generalization. Motors do indeed attempt to be constant-power loads and behave as you described (current varies inversely with voltage), but the vast majority of residential loads tend to be constant-impedance loads (current varies proportionately with voltage).

With incandescent bulbs, for one example, if the voltage sags, so does the current. Only if a larger bulb is substituted would the user cause an increase in $$ as a result. With electric heat, the heat will run cooler, but will need to run longer in compensation to keep the thermostat satisfied.
 

kwired

Electron manager
Location
NE Nebraska
Thanks for the responses. To M_J_C's last post, yes I understand the NEC is a minimum standards guide, not a design guide, and also the function of UL listing. I'm not a licensed electrician. I went to home depot and bought the preferred receptacles by Leviton and wired them in my house. If we are talking about circuits larger than 15A with high load, then I would agree backstabbing may not be best practice. But for 15A receptacles with cell phone chargers, TVs, lamps etc, even a heater for that matter, pulling less than 12A, I do not see the issue with using the quick connect ports that the manufacturer provided and UL approved, nor inefficient energy transfer, etc with such small loads.

Yes, there is always going to be something better with everything in life, but for the amount of comments on the web stating that back-stabbed receptacles are less than adequate, doesn't seem to line up with manufacturer and UL.

Screw connections can loosen and fail as well if not installed properly. Even if you pigtail around the screw, the connection can still loosen, and resistance can build up. And we also don't know what any given receptacle was exposed to in it's past life...was the faulty backstabbed receptacle in question connected to a fully loaded surge protector with 6 devices on it, etc.

Thanks again for the posts.
Heater is exactly the kind of load that runs for long enough periods that heating effects in any poor connection last for long enough cycles that the connection begins to degrade much quicker than for lighter loads or even heavy loads that never have much duration. Doesn't matter if it is a backstab connection, screw terminal, plug to connector pressure, etc.
 

kwired

Electron manager
Location
NE Nebraska
The POCO metering device generally uses CT's at the service entrance point to measure how much $$ is passing through, the greater the voltage drop at the point of use, the more current the device uses (generally, but not always) to achieve its rated output. Ever notice a motor that has a two amperage ratings, one for 230V and and one for 208V? The same is true for most loads, as voltage drops, current goes up, not to mention incidental heating of the structure, something we don't need in the south!. Here are some references:
https://www.ecmweb.com/electrical-testing/minimize-voltage-drop-upsizing-your-conductor-size
https://www.copper.org/environment/...y-efficiency/education/archive/onesizeup.html
https://www.energy.gov/sites/prod/files/2014/04/f15/motor_tip_sheet8.pdf
https://iaeimagazine.org/magazine/2009/07/16/energy-loss-global-warming-and-voltage-drop/
Ever multiplied the amps by their respective volts - you still get same volt-amps, which after you consider power factor is going to give you watts - you are billed for energy used as watt-hours.

Where increase in wire size for VD gives you any savings is because of lost watts in the circuit conductors. But what was earlier mentioned means a large industrial motor with significant VD losses on the conductors is going to lose many more watts over a 24/7 time frame than some item that has losses on lesser scale and especially if it doesn't get same run time.

Yes heat lost into the structure is also creating more energy demand because now the cooling system needs to remove that heat. Depending on the load served this may not matter much though. If it is a heat producing load you are adding heat to the structure anyway. If you make toast in the morning in your kitchen, heat from both the toaster and any heat lost in the circuit to your toaster are both still lost to the inside of your house and the cooing system needs to remove that heat, but there is a huge difference in amount of heat from making that couple slices of toast vs having same wattage of space heater running inside the house all day long.
 

kwired

Electron manager
Location
NE Nebraska
I must disagree with that generalization. Motors do indeed attempt to be constant-power loads and behave as you described (current varies inversely with voltage), but the vast majority of residential loads tend to be constant-impedance loads (current varies proportionately with voltage).

With incandescent bulbs, for one example, if the voltage sags, so does the current. Only if a larger bulb is substituted would the user cause an increase in $$ as a result. With electric heat, the heat will run cooler, but will need to run longer in compensation to keep the thermostat satisfied.
With electric heat as long as line losses occur inside the area to be heated you didn't lose anything for operation costs.
 
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