Discuz! Board

 找回密码
 立即注册
搜索
热搜: 活动 交友 discuz
查看: 5|回复: 0

Ungrounded duplex outlet

[复制链接]

9万

主题

9万

帖子

29万

积分

论坛元老

Rank: 8Rank: 8

积分
293221
发表于 2021-9-1 23:14:29 | 显示全部楼层 |阅读模式
Morning all!Why is this still available?

Even in a house or building with a two wire electrical system why not just use a standard grounded duplex outlet?I know it would not be grounded but it would keep you from having to use one of these which wouldn't be grounded either!


Reply:

Originally Posted by rexcormack

Why is this still available?
Reply:I have to study, We don't want people to believe an outlet (receptacle) is grounded when it isn't. Last Code cycle, it was legal to replace a worn out two wire receptacle. Alternatively, you could use a GFCI & label it NOT GROUNDED.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:

Originally Posted by BaTu

I can't Imagine....Where was this "still available"?
Reply:

Originally Posted by Willie B

I have to study, We don't want people to believe an outlet (receptacle) is grounded when it isn't. Last Code cycle, it was legal to replace a worn out two wire receptacle. Alternatively, you could use a GFCI & label it NOT GROUNDED.
Reply:It was somewhere in the 1960s that grounded receptacles were first required. As many applications code isn't enforced, it went on years after that code was ignored, or "electricians" didn't know of the new requirement. There are miles of ungrounded NM cable still in use, earliest manufactured in the late 1930s It was cloth jacketed, and BULKY. I'd guess the insulation & jacket was linen impregnated with rubber. Strip a bit of it your hands look like you just cleaned out a boiler! By the 1950s NM had become plastic insulation, fabric jacket. Like the earlier stuff, it included a lot of paper filler. Knob & tube is the earliest wiring method I have worked with. In a rural area lots of old homes had it & still do. villages got power lines from 1900 to 1920. Farms were much later. Prosperous farms had Delco Systems. A DC generator charged huge glass batteries. They too had knob & tube wiring. Until amateurs tamper with it, or insulation gets blown into a house its fire safety record is enviable.By 1938, Roosevelt initiated RURAL ELECTRIFICATION. Houses & farms too spread out to be profitable for power companies to build lines to them got power all the construction paid for by the Federal Government. Greatest hazard with this innovation was the soldered connections were abandoned. Twisted connections were the norm. These were taped with some questionable products. As time went on the copper at these connections oxidized, oxide is less a good conductor. As electrons struggle to jump from one piece of wire to the next the resistance generates heat. Heat melts compounds from the tape. These further resist flow of electrons, causing more heat. If not repaired, it results in a lot of heat. If air & fuel are present, fire results. BX is another story. DO NOT USE BX AS A GROUND CONDUCTOR! BX is prone to short circuit. The jagged jacket cuts tend to cut the insulation in typical installations. The spirals of jacket steel tend to serve as inductance coils, generating heat while not conducting enough current to trip a breaker. IF YOU HAVE BX, GET RID OF IT!When we talk about electrical safety we usually talk about fire safety & electrocution. While I don't know of anyone who died from electrocution for lack of a ground conductor in their receptacle, I know of thousands of buildings that burned for bad connections. I don't understand the emphasis on grounding & ground fault circuit interrupters. I see greater hazards to consider.Last edited by Willie B; 04-28-2021 at 04:11 PM.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:

Originally Posted by BaTu

But are there, non metallic,  "2 wire" applications (where the Bond isn't connected thru the mounting screws) really out there?I mean, a plastic box that's what? Cabled with BX? Romex without a Bond - did that even ever exist?The application at ALL doesn't make sense to me and Certainly not enough for Lowes to carry it (and would most likely be purchased by homeowners who don't know any better....)This was clearly a mistake by a purchasing agent who should lose his job


Reply:Every big box store sells them and they are a legal replacement for a two wire ungrounded receptacle. It is not always possible to provide GFCI protection to every location so we sometimes use those where we can't provide GFCI or grounding. It is illegal and poses a shock hazard to install a 3 prong receptacle on an ungrounded, non-GFCI protected location. The reason is (and I have seen it happen) if a short of the hot conductor to the box occurs it energizes the metal strap which in turn energizes the grounding hole which in turn energizes the metal parts of what ever is plugged into it with a 3 wire cord. It can happen easier than you think when people go messing with old, brittle wires to change the outlet, insulation falls off and bare wire contacts the box when they shove it back in. The one I remember was a college rental, the kids were getting shocked every time they went barefoot to the fridge to get a beer. Luckily nobody got killed but there was another one where it was a freezer in a garage and a guy with no shirt on sat on the floor and leaned his sweaty back against the freezer and it killed him. That was one of the death certificates produced when the CMP was adding the garage GFCI requirements.Last edited by bigb; 04-28-2021 at 08:50 PM.Miller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:Must be them special ones for wiring with zip cord. It's only 2 wire. LMAO !!! It is a joke.
Reply:

Originally Posted by danielplace

Must be them special ones for wiring with zip cord. It's only 2 wire. LMAO !!! It is a joke.
Reply:

Originally Posted by Willie B

The jagged jacket cuts tend to cut the insulation in typical installations. The spirals of jacket steel tend to serve as inductance coils, generating heat while not conducting enough current to trip a breaker. IF YOU HAVE BX, GET RID OF IT!
Reply:

Originally Posted by BaTu

I think that's a bit of an overreaction....

Every house built before the mid 70's around me is wired with BX (as is My house) and it's not a cause for concern for them all I'm sure. When I wire, I will use BX today if the circuit is being extended from a BX box (new wiring is, of course, NM). Properly cut & sleeved BX isn't any kind of hazzard really, I can see before the Roto Tool (when you had to use a hacksaw & dykes to cut it back) and maybe guys skipped the protective sleeve it created issues, and certainly any Wet placement (where you're combining steel, zink, aluminum, and copper) is a Terrible idea! But, you want to add a ceiling fixture to an existing room and the sw box is metal, with the BX "double sided, single screw, clamp" in the back, converting it all to NM seems unnecessary to me. I'll put 10ft of BX on to it anyday


Reply:

Originally Posted by Willie B

No, there is great confusion between BX, and MC And AC. BX is steel jacketed with fabric inner insulation. It fell from favor in the late 1930s when steel was needed for the war effort. As designed, the jacket served as a ground conductor, but current path was not linear, it tended to flow as the jacket ran in a spiral. this formed a magnetic impedance, limiting current. Literally an inductive heater, it could get red hot without tripping a breaker. If box sizes were adequate, it wasn't always going to short, but boxes were tiny (typically 9 cubic inch). I've seen as many as 5 BX cables plus a light in one. Conductors are smashed into these boxes. Newer armored cables each have some means to prevent inductive heating in a short circuit. Some have ground conductors, others a bare aluminum strand inside the jacket.
Reply:

Originally Posted by Willie B

Don't laugh! My father didn't start his electrician career until late 30s. Prior to that, Mother's brother "wired" my grandmother's house. A pre existing outlet was near the kitchen table. He plugged into it and ran throughout the house with #18 lamp cord. They used to sell receptacles you screwed half to the wall, lamp cord passed & you screwed the other half on, piercing the insulation. There must have been 500 feet of this junk! It ran across ceilings, and under rugs. 60 years later new owners bulldozed the house. No it never burned.
Reply:

Originally Posted by danielplace

Willie,Yes they still sell those zip cord outlets and lamp sockets that pierce the zip cord. Crazy how things made do back in the day. Now just about every dang circuit in a house needs AFCI protection.Talk about not catching on fire.I would never be so lucky. I was maybe 6 or 7 and had some DC electronics running on speaker wire on other side of room powered by a hefty RV type power supply. Don't you know something at far end went dead short and wire lit every thing on fire around the room. I managed to get it shut off and fires out. First bout with fire.Second was doing something at local park with friends and fire at about the same age and I ended up starting a fire that got out of control. We were gone when fire department got there and it spread to dry woods and they fought fire all day and into the night. Of course they didn't know who did it so what the heck I went to help. Ended up on a fire truck for several hours with some firemen AND on the front page of the news paper. "This little boy helps stand guard over hot spot from fire today in Boynton Beach".  True story. I just had some titanium of my mill catch fire from WD-40 soaked mill shavings that ignited from a angle grinder. Crazy it was popping and shooting off the table glowing and on fire. In seconds I had already snatched the entire mill table and all and drug right out the overhead door(back still hurts, lol) Grabbed the air hose and blew all remaining Titanium off the mill that was still on fire out onto driveway. Then raced back in to extinguish little fires that were starting or still going inside. Jimmity Christmas never a dull moment.
Reply:

Originally Posted by Willie B

BX is no longer manufactured, and other armored cables don't pose the same risk.
回复

使用道具 举报

您需要登录后才可以回帖 登录 | 立即注册

本版积分规则

Archiver|小黑屋|DiscuzX

GMT+8, 2025-12-19 20:50 , Processed in 0.070610 second(s), 18 queries .

Powered by Discuz! X3.4

Copyright © 2001-2021, Tencent Cloud.

快速回复 返回顶部 返回列表