Ungrounded Outlets

[fan-of-fans]

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.

 

[gizmo]

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?

 

[DADoES]

 
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.

 

[adam-aussie-vac]

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

 

[Chetlaham]

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.

 

 

 

 

[Chetlaham]

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.

 

[Chetlaham]

Australian Adapter

The modern AUS adapter fits perfectly in Chinese and old non NEMA US versions- 

 

[Chetlaham]

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.

 

[Chetlaham]

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-Straight-Receptacle-Suitability-Industrial/dp/B08HSYF96M/ref=sr_1_27?crid=L1XFT6TPREM2&keywords=nema%2B10-50&qid=1681089053&sprefix=nema%2B10-50%2Caps%2C119&sr=8-27&th=1

 

[adam-aussie-vac]

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

 

[Chetlaham]

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.

 

[Chetlaham]

2 Prong Combo Light Socket

This I came across on Amazon at a reduced price. When I saw it I had to get it.  

 

[sudsmaster]

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.

 

[Chetlaham]

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...

 

[Chetlaham]

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. 

 

 

Split-phase electric power - Wikipedia

en.wikipedia.org

 

[circlew]

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]

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

 

[Chetlaham]

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.

 

[donprohel]

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)

 

[Chetlaham]

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/