The receptacle pictured above (reply #28) is a 20 amp 120 volt device (NEMA 5-20). These are installed mainly in kitchens and laundry rooms, as a few appliances have plugs that require these. Also seen in workshops and garages, as some tools require them. Most commonly used in commercial buildings.
Ungrounded Outlets
- Thread starter Chetlaham
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My question is
In regards to the Nema 620, if someone were to import compliance from a 220 V single phase country and connected to the 220 V split phase found in the USA, would that appliance work happily with that? excluding the usual suspects like motor powered clocks and microwaves or things that use the AC frequency for time
In regards to the Nema 620, if someone were to import compliance from a 220 V single phase country and connected to the 220 V split phase found in the USA, would that appliance work happily with that? excluding the usual suspects like motor powered clocks and microwaves or things that use the AC frequency for time
whitewhiskers
Well-known member
re: reply# 24
Chetlaham, thank you for posting the link to the 1956 Wiring Simplified. My copy is the 39th edition from 1999, purchased in the electrical department of Home Depot. Even though a lot has changed from 1956, some things stay the same. Notice how the 1956 receptacle diagram uses ungrounded outlets while the 1999 diagram has the ground hole. The ground wire isn't shown though.
Chetlaham, thank you for posting the link to the 1956 Wiring Simplified. My copy is the 39th edition from 1999, purchased in the electrical department of Home Depot. Even though a lot has changed from 1956, some things stay the same. Notice how the 1956 receptacle diagram uses ungrounded outlets while the 1999 diagram has the ground hole. The ground wire isn't shown though.
Working Happily
Much indeed. As long as said appliance can handle 60Hz, which most can, even if listed for only 50Hz, can't tell the difference. Schuko plugs aren't even polarised so the fact any leg could/is live is taken into account safety wise.
I do this in my own home. I refuse 120 volts when I can avoid using it. I find the added engineering effort of bootlegging an impractical half voltage out of a system so odd/dated/absurd/risky. Extra effort and material just stepping backwards.
Much indeed. As long as said appliance can handle 60Hz, which most can, even if listed for only 50Hz, can't tell the difference. Schuko plugs aren't even polarised so the fact any leg could/is live is taken into account safety wise.
I do this in my own home. I refuse 120 volts when I can avoid using it. I find the added engineering effort of bootlegging an impractical half voltage out of a system so odd/dated/absurd/risky. Extra effort and material just stepping backwards.
Being honest even the new additions of the book come across as dated, but, at the same time, as long as the graphics are revised to follow the lasted addition of NFPA-70 it suites its job well in teaching people.
There is one important thing that I want to clarify about that book and most other wiring books. When they use the term"ground" "going to ground" "traveling to the ground" or "grounded" in relation to clearing a fault they are referring to the path electricity takes back to the utility transformer and not the earth or soil itself. Very common misunderstanding. A typical ground rod comes in at 25 ohms and will not trip a breaker, where as a typical service neutral rarely exceeds 0.1 ohms. Fault current travels back to the main panel (or disconnect) via metal conduit or grounding conductors, to the grounding terminal in the enclosure, through the main bonding jumper, to the neutral bar and up through the service neutral going back to the transformer. It is one closed loop. The soil, earth or terra firma makes no difference in that regard.
There is one important thing that I want to clarify about that book and most other wiring books. When they use the term"ground" "going to ground" "traveling to the ground" or "grounded" in relation to clearing a fault they are referring to the path electricity takes back to the utility transformer and not the earth or soil itself. Very common misunderstanding. A typical ground rod comes in at 25 ohms and will not trip a breaker, where as a typical service neutral rarely exceeds 0.1 ohms. Fault current travels back to the main panel (or disconnect) via metal conduit or grounding conductors, to the grounding terminal in the enclosure, through the main bonding jumper, to the neutral bar and up through the service neutral going back to the transformer. It is one closed loop. The soil, earth or terra firma makes no difference in that regard.
polkanut
Well-known member
Our house is a mixture of grounded & ungrounded. The original part of our house was built in 1925, and the addition was built around 1962. Funny thing though, the man who owned the house before us was in the electric motor repair business for over 50 years. You would've thought that he would have updated the electrical over the years, but this was not the case. In fact, we upgraded to a 100-amp service with a breaker box vs the old 60-amp service with only 4 fuses for the entire house.
Reply 33, I would absolutely love to see a thread on 220 V
Appliances and how you got your system to work
Plus I do hope you have a 220 V coffee maker, if you don’t I can happily supply one
Appliances and how you got your system to work
Plus I do hope you have a 220 V coffee maker, if you don’t I can happily supply one
fan-of-fans
Well-known member
Re ungrounded with centered slots on Amazon
That is interesting. I do know at Home Depot the outlet on the display has the slots centered, but if you look at the ones for sale in the bin, they aren’t centered.
As for other brands, I believe Pass and Seymour/Legrand may still sell ungrounded ones with centered slots. But since Lowes switched to Cooper/Eaton here, nobody seems to sell P&S around here, so I cannot confirm.
The horizontal blade 20 amp plugs are also used on some small commercial cooking equipment that requires a 20 amp circuit. I can’t think of anything that I’ve seen sold toward residential use that does though.
The 20 amp outlets are usually seen in kitchens and baths of houses around here built in 80s and later, although even n the grandmothers 1978 home had them in the kitchen. I don’t know that there’s any code that says they have to be used specifically.
That is interesting. I do know at Home Depot the outlet on the display has the slots centered, but if you look at the ones for sale in the bin, they aren’t centered.
As for other brands, I believe Pass and Seymour/Legrand may still sell ungrounded ones with centered slots. But since Lowes switched to Cooper/Eaton here, nobody seems to sell P&S around here, so I cannot confirm.
The horizontal blade 20 amp plugs are also used on some small commercial cooking equipment that requires a 20 amp circuit. I can’t think of anything that I’ve seen sold toward residential use that does though.
The 20 amp outlets are usually seen in kitchens and baths of houses around here built in 80s and later, although even n the grandmothers 1978 home had them in the kitchen. I don’t know that there’s any code that says they have to be used specifically.
That 5-20R with 1 horizontal, one vertical slot is interesting. Do they always have a ground pin?
Without the ground pin it looks the same as our ELV (Extra Low Voltage) plug and socket in Australia, used for low voltage DC wiring - they are 2-pin only, one horizontal and one vertical pin.
They are somewhat unusual these days, used to be for 32V DC remote area homes with a 32 volt DC home battery system, powered by a wind generator and/or a diesel powered home lighting plant. You could buy vacuum cleaners, washing machines, irons and lights that ran on 32V DC with these plugs. They have come back into use in the solar era, mostly for 12V DC, now sometimes used in RVs for a more reliable connection than a 12 volt cigarette lighter plug.
I have them in my home, our place is wired dual-voltage, standard Australian 240V AC power outlets throughout the home and 12V DC outlets in a couple of strategic places only - mainly to run small devices direct from the DC batteries without the inverter. They don't get used much, our usage has changed. Our battery system is 24V DC and there is a DC
C converter to provide 12V from the 24V batteries.
Could be spectacular if someone plugged an Australian 12V or 32V DC appliance into a US 120V 20A AC socket...
Without the ground pin it looks the same as our ELV (Extra Low Voltage) plug and socket in Australia, used for low voltage DC wiring - they are 2-pin only, one horizontal and one vertical pin.
They are somewhat unusual these days, used to be for 32V DC remote area homes with a 32 volt DC home battery system, powered by a wind generator and/or a diesel powered home lighting plant. You could buy vacuum cleaners, washing machines, irons and lights that ran on 32V DC with these plugs. They have come back into use in the solar era, mostly for 12V DC, now sometimes used in RVs for a more reliable connection than a 12 volt cigarette lighter plug.
I have them in my home, our place is wired dual-voltage, standard Australian 240V AC power outlets throughout the home and 12V DC outlets in a couple of strategic places only - mainly to run small devices direct from the DC batteries without the inverter. They don't get used much, our usage has changed. Our battery system is 24V DC and there is a DC
C converter to provide 12V from the 24V batteries.Could be spectacular if someone plugged an Australian 12V or 32V DC appliance into a US 120V 20A AC socket...
fan-of-fans
Well-known member
Horizontal slot with ground?
My guess is yes, likely they would always have a ground prong. All the plugs I’ve seen with them did. Just being that most of that type of equipment is made of metal and possibly used in wet environments. And most items with those 20 amp plugs I’d guess would be made in the era that grounding was common.
Now what interests me also, are those old receptacles with both slots being T slots. From my understanding there were some early 15 amp plugs made that had two horizontal slots instead of the parallel ones. But I can’t ever encounter finding one of these.
Also, I have some older receptacles in my collection, including a crows foot receptacle that was used for early grounded appliances prior to the 1950s!
The crows foot slot pattern looks similar to the ones to the right of your picture.
My guess is yes, likely they would always have a ground prong. All the plugs I’ve seen with them did. Just being that most of that type of equipment is made of metal and possibly used in wet environments. And most items with those 20 amp plugs I’d guess would be made in the era that grounding was common.
Now what interests me also, are those old receptacles with both slots being T slots. From my understanding there were some early 15 amp plugs made that had two horizontal slots instead of the parallel ones. But I can’t ever encounter finding one of these.
Also, I have some older receptacles in my collection, including a crows foot receptacle that was used for early grounded appliances prior to the 1950s!
The crows foot slot pattern looks similar to the ones to the right of your picture.
right side of my picture
Right side of my picture is a regular 240 V 10 A Australian power outlet (we call them "power points.") They are required to be individually switched here. 240V x 10 A = 2400W max. per socket.
I remember seeing them, or something that looked like them, in a hospital in Chicago in 1982 - but unswitched. I guess they were used for some 240V medical equipment?
Right side of my picture is a regular 240 V 10 A Australian power outlet (we call them "power points.") They are required to be individually switched here. 240V x 10 A = 2400W max. per socket.
I remember seeing them, or something that looked like them, in a hospital in Chicago in 1982 - but unswitched. I guess they were used for some 240V medical equipment?
A piece of network equipment at the Internet service where I worked required 120v 20a. The APC UPS unit for it had an optional backplane with two of the required receptacles.
Oh, you’re probably thinking about the 6–10 Nema
It’s electrically compatible with Australian stuff but that plug-in outlets up are rated for 15 A at 120 and 10 at 240
It’s electrically compatible with Australian stuff but that plug-in outlets up are rated for 15 A at 120 and 10 at 240
Chinese Version
I have a few of these. This was one of several socket types I experimented with until I settled with schukos. Some models have a socket switch others do not. Some come with a parallel combo NEMA 1-15 / Euro plug.
I have a few of these. This was one of several socket types I experimented with until I settled with schukos. Some models have a socket switch others do not. Some come with a parallel combo NEMA 1-15 / Euro plug.
Old US non NEMA Version
I personally wish this was the dominant outlet in the US for many reasons, and it was supposed to be so, unfortunately someone must've traveled back in time screwing with critical events resulting in the after-thought NEMA 1-15/NEMA 5-15 we are stuck with today.
I personally wish this was the dominant outlet in the US for many reasons, and it was supposed to be so, unfortunately someone must've traveled back in time screwing with critical events resulting in the after-thought NEMA 1-15/NEMA 5-15 we are stuck with today.
Australian Adapter
The modern AUS adapter fits perfectly in Chinese and old non NEMA US versions-
The modern AUS adapter fits perfectly in Chinese and old non NEMA US versions-
NEMA 10-50
This is a NEMA 10-50 range receptacle rated 50 amps and considered "ungrounded" in NEMA standards .
I personally wish the NEMA 10-20, 10-30 and 10-50 were re-classified as grounding types (as has been done in some parts of the world) plus reintroduction of the old US crow foot.
This is a NEMA 10-50 range receptacle rated 50 amps and considered "ungrounded" in NEMA standards .
I personally wish the NEMA 10-20, 10-30 and 10-50 were re-classified as grounding types (as has been done in some parts of the world) plus reintroduction of the old US crow foot.
Chinese Getting It Right
The Chinese are building these as grounding versions (technically incorrect by US standards) where the neutral pole is the grounding pole with a bonding strap to the yoke of the receptacle, pole Y as the hot and pole X is the second live or neutral when used in a 230/400Y system.
Very smart, and common sense. The round ground pins on other NEMA and NEMA-esque receptacles are essentially after thoughts, and do not make surface gripping contact the way flat contacts do.
https://www.amazon.com/Sintron-Stra...89053&sprefix=nema+10-50,aps,119&sr=8-27&th=1
The Chinese are building these as grounding versions (technically incorrect by US standards) where the neutral pole is the grounding pole with a bonding strap to the yoke of the receptacle, pole Y as the hot and pole X is the second live or neutral when used in a 230/400Y system.
Very smart, and common sense. The round ground pins on other NEMA and NEMA-esque receptacles are essentially after thoughts, and do not make surface gripping contact the way flat contacts do.
https://www.amazon.com/Sintron-Stra...89053&sprefix=nema+10-50,aps,119&sr=8-27&th=1
As an Amazon Associate we earn from qualifying purchases.
Reply 44
Oh wow I would love to get my hands on one of those outlets, speaking Of outlets, there’s also this one as well which I actually use on a daily basis, And yes it actually does fit USATwo gang electrical boxes, and it even has those little tabs that you can break off to separate an outlet into to outlets
Prepare to be amazed or horrified
Oh yeah the second photo is the cord that I use on the Two prong outlet with the Center screw as ground
Oh wow I would love to get my hands on one of those outlets, speaking Of outlets, there’s also this one as well which I actually use on a daily basis, And yes it actually does fit USATwo gang electrical boxes, and it even has those little tabs that you can break off to separate an outlet into to outlets
Prepare to be amazed or horrified
Oh yeah the second photo is the cord that I use on the Two prong outlet with the Center screw as ground
Amazon is the key. Try the US version, among others, that have on/off popups with Chinese sellers. Ebay for the old stuff.
In Japan they'll do that, where the cord has a separate ground wire and separate ground screw on the socket. Not something I approve of, but common there it seems.
In Japan they'll do that, where the cord has a separate ground wire and separate ground screw on the socket. Not something I approve of, but common there it seems.
2 Prong Combo Light Socket
This I came across on Amazon at a reduced price. When I saw it I had to get it.
This I came across on Amazon at a reduced price. When I saw it I had to get it.
sudsmaster
Well-known member
Technically speaking, the 10-50 and similar 240 volt receptacles are NOT fully grounded. This has been explained elsewhere in this thread (I think). For the safest ground, a separate path for the ground is needed; the 10-50 and similar outlets compromise this with the neutral wire. It's no safer (and perhaps less safe) than a 120 volt outlet with just two paths. One for hot, the other for neutral/ground.
That said, my laundry area in the main house, as well as the 240 volt outlets in the workshop, have only three prong outlets. Since I rarely use any of these (the dryer is gas), I'm in no hurry to change them to the latest and safest version. Some day!
Oh wait... there is a 240 volt air compressor in the workshop that I use whenever I need to fill tires. It also has a 3 prong plug. Oh well.
That said, my laundry area in the main house, as well as the 240 volt outlets in the workshop, have only three prong outlets. Since I rarely use any of these (the dryer is gas), I'm in no hurry to change them to the latest and safest version. Some day!
Oh wait... there is a 240 volt air compressor in the workshop that I use whenever I need to fill tires. It also has a 3 prong plug. Oh well.
Correct
Under NEMA they are classified as non grounding H-N-H.
However, my line of thinking is have everything go straight 240 volts. No internal 120 volt components. Have everything be 3 wire, H-G-H, and just reclassify the 10-XXs and 18-XXs as grounding types. Have the crow foot become dominant. Ditch all the other NEMA types.
At least in my world...
Under NEMA they are classified as non grounding H-N-H.
However, my line of thinking is have everything go straight 240 volts. No internal 120 volt components. Have everything be 3 wire, H-G-H, and just reclassify the 10-XXs and 18-XXs as grounding types. Have the crow foot become dominant. Ditch all the other NEMA types.
At least in my world...
Reply 36
The US residential system is split phase, a center tapped 240 volt winding. Each home receives two hots and one grounded neutral. The system is TN-C-S or rather technically PME. Both hot legs are 180* out of phase, so between each hot and neutral (of ground) we get 120 volts, but between each hot wire we get full 240 volts.
https://en.wikipedia.org/wiki/Split-phase_electric_power
The US residential system is split phase, a center tapped 240 volt winding. Each home receives two hots and one grounded neutral. The system is TN-C-S or rather technically PME. Both hot legs are 180* out of phase, so between each hot and neutral (of ground) we get 120 volts, but between each hot wire we get full 240 volts.
https://en.wikipedia.org/wiki/Split-phase_electric_power
There are already grounded receptacles for equipment that operates solely at 240 volts. For example, the NEMA 6-50 is rated for 50 amps, no neutral - just the equipment ground. That said, I've seen installations that used the 10-50 for that purpose.
ozzie908
Well-known member
UK outlets
May leave some people agog but they are all switched and all earthed/grounded even light fittings are grounded.
No matter what you choose to connect there is no extra wiring needed apart from Stove's and showers.
All plugs are three prong too and each plug is fused for safety they may be bulky but it makes life safer and easier
May leave some people agog but they are all switched and all earthed/grounded even light fittings are grounded.
No matter what you choose to connect there is no extra wiring needed apart from Stove's and showers.
All plugs are three prong too and each plug is fused for safety they may be bulky but it makes life safer and easier
Reply 54
I know
I'm saying ditch all 120 volt components and just reclassify the NEMA 10 and 18 as grounding types. Fewer receptacles moving forward.
Regarding the UK, I think they have on of the best systems in the world.
I know
I'm saying ditch all 120 volt components and just reclassify the NEMA 10 and 18 as grounding types. Fewer receptacles moving forward.
Regarding the UK, I think they have on of the best systems in the world.
UK plugs
I am not at all sure that the fuse make UK plugs much safer: the fuse in the plug is required because of the very peculiar way electric circuits are made in the UK, and the fuse is there to protect the wirings in the wall.
I feel much, much, much safer with the Residual Current Devices I have now than with fused plugs.
And it is true that all the plugs have three pins, but that does not mean that any device is grounded: sometimes the ground plug is just plastic and the device is not grounded at all (for instance, plug-in power supplies are not grounded)
I am not at all sure that the fuse make UK plugs much safer: the fuse in the plug is required because of the very peculiar way electric circuits are made in the UK, and the fuse is there to protect the wirings in the wall.
I feel much, much, much safer with the Residual Current Devices I have now than with fused plugs.
And it is true that all the plugs have three pins, but that does not mean that any device is grounded: sometimes the ground plug is just plastic and the device is not grounded at all (for instance, plug-in power supplies are not grounded)
The wiring in the wall is already protected via MCB. The fuse protects to cord itself and also reduces the amount incident energy released at the point of short circuit, if the cord became shorted. With a 32 amp MCB the cord may melt before the MCB trips (adiabatic limit of the cord's conductor exceeded), or just arc/sputter at the point the cord is damaged, but with the fuse (in the plug) a fault in the cord instantly blows said plug fuse before anything bad can happen. The fuse responds faster, at a lower current, than the 32 amp MCB can.
Ring circuits, at least back in the day, allowed much more power to be supplied to a building level via less copper. The load diversity also helped maximize the savings as it is not likely everything would be on at once. A whole residential lower level could be fed from a single 32 amp circuit, a second 32 amp ring socket circuit for the upstairs, then one or two 6 or 10 amp radial lighting circuits. A 40 amp for the cooker, maybe another circuit for the boiler.
There has to be a ground pin on the plug even if the appliance is double insulated as the safety shutters in the plug will not open. Ingenious idea as the shutters provide both child protection and rejection of a plug missing its ground pin. In the US missing equipment ground pins on metal tools like drills made for the bulk of electrocutions.
Attached Image courtesy of "Fatally Flawed"
https://electrical.theiet.org/wiring-matters/years/2020/80-may-2020/socket-outlet-protectors/
Ring circuits, at least back in the day, allowed much more power to be supplied to a building level via less copper. The load diversity also helped maximize the savings as it is not likely everything would be on at once. A whole residential lower level could be fed from a single 32 amp circuit, a second 32 amp ring socket circuit for the upstairs, then one or two 6 or 10 amp radial lighting circuits. A 40 amp for the cooker, maybe another circuit for the boiler.
There has to be a ground pin on the plug even if the appliance is double insulated as the safety shutters in the plug will not open. Ingenious idea as the shutters provide both child protection and rejection of a plug missing its ground pin. In the US missing equipment ground pins on metal tools like drills made for the bulk of electrocutions.
Attached Image courtesy of "Fatally Flawed"
https://electrical.theiet.org/wiring-matters/years/2020/80-may-2020/socket-outlet-protectors/
"whole residential lower level"
Placing everything on any particular floor level or major area of a building on one circuit is very poor design. In the event the circuit breaker trips or fuse blows, that entire area is left in the dark. Some friends moved into an old house wired like that, and a fuse blew leaving the entire first floor dark except the bathroom. The 2nd floor was also on one circuit. They soon had the house totally rewired. Also, kitchen appliance circuits should never serve any other rooms except a dining room or pantry.
Placing everything on any particular floor level or major area of a building on one circuit is very poor design. In the event the circuit breaker trips or fuse blows, that entire area is left in the dark. Some friends moved into an old house wired like that, and a fuse blew leaving the entire first floor dark except the bathroom. The 2nd floor was also on one circuit. They soon had the house totally rewired. Also, kitchen appliance circuits should never serve any other rooms except a dining room or pantry.
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