Creative Technology

[bennie]

I know that I complain and critize a whole lot. I hope it does not bore or offend anyone. My only intent is to clarify and correct mistakes from the past. I may have grandchildren interested in becoming electricians, they do not need a lot of baggage left by past generations.

I would like to point out another "old wives tale"
(no offense intended to old wives), concerning the myth that 3 wire cables were used for panel feeds, range, and dryer wiring because of the copper shortage in War II.

Number one proof of the error is that no domestic home construction was done during the war. The war was only 4 years.

Number two proof of error; No appliances were manufactured during the war.

Number three validation of the error is; The 1940 Edition of the NEC permitted 3 wire cables to the above named equipment. The war started in late 1941.

The war excuse was the substantiation for adding the fourth wire, and separating the neutral ground at panels on the load side of the main.

Creative technology for marketing purposes?

 

[templdl]

Re: Creative Technology

To be honest it is of my opinion that sharing a neutral with a ground, that is grounding the appliance with the grounded neutral was considered to be OK because the possibility of a failed or compromised neutral was not considered to be a significant risk.
They also didn't recognize the danger of possible neutral current being turner loose of the appliance enclosure if the neutral connection failed. It assumes that even though a person who is grounded and touches the enclosure essentially places themselves in parallel with the grounded neutral conductor that 100% of the neutral current will take the neutral conductor path.
Has there been an studies that documents electrocution or shocks to show the possible danger of grounding an appliance with a neutral?
Our knowledge today illustrates the importance we place on the proper grounding of electrical equipment, that a neutral is a neutral, even though it is commonly grounded and is part of the electrical circuit which supplies power to the connected load, and the EGC is dedicated to grounding.
In my own home, who I'm the second owner of, the electric dryer plug was 3w. However, the actual cable run to the outlet was 3w, w/gr which made it easy for my to replace the 3w outlet with one that was the grounding type.

 

[templdl]

Re: Creative Technology

Oh yes, I forgot to mention the little importance that was place on ground rods an grounding water pipe, etc. How many grounding wires have corroded away from water pipes and failed? how many ground rod connections failed? Look at the little importance that was placed of grounding the BX cable exterior casing, that is expecting that tiny aluminum wire and all those BX connectors to carry through a ground. How many Aluminum wires have broken off, how many BX connectors have come loose? And what about all of the 2/w NM cable that's out there?
Was grounding and important issue? I think not.

 

[bennie]

Re: Creative Technology

Templdl: You hear the same drumbeat as I. I agree with you on everything, I hope my support does not make you an outcast. If it does, welcome to my world.

 

[pierre]

Re: Creative Technology

Bennie
I read somewhere that the reason for the range/dryer wiring was because of the depression. I read that not too long ago, I will try to dig up the article. I cannot remember if it was on the web or a magazine.

Pierre

 

[bennie]

Re: Creative Technology

Pierre: The depression had the opposite effect. The Rural Electrification Act (REA) started in 1935. Manpower and material was plentiful. This was part of the plan to break the depression.

The reason for the 3 wires is because 3 is all that's needed.

 

[Guest]

Re: Creative Technology

Originally posted by templdl:
<snip>In my own home, who I'm the second owner of, the electric dryer plug was 3w. However, the actual cable run to the outlet was 3w, w/gr which made it easy for my to replace the 3w outlet with one that was the grounding type.

Is the N-G still bonded within your dryer?

Here's what happened to Mike Holt:
Mike Holt purchased an electric dryer from Frigidaire.

[ October 06, 2003, 12:55 AM: Message edited by: awwt ]

 

[tonyi]

Re: Creative Technology

Originally posted by templdl:
expecting that tiny aluminum wire and all those BX connectors to carry through a ground. How many Aluminum wires have broken off, how many BX connectors have come loose?

The connectors are critical in an AC cable system, but then they're equally critical for any metallic conduit where there's no ground wire being pulled.

The alumium wire in AC cable isn't really a ground wire. It could break in numerous places along a run without seriously compromising the armor's ability to be a EGC. Consider what the net practical effect in reality of AC minus a bond wire would be - its really no different than individual conductor pull through Flex where no gnd is pulled - and we're allowed to use up to 6' of Flex as EGC (I always pull gnd, but its not required unless there's more than 6' in a run). A break in the bond wire only results in the armor carrying the complete fault current for a few spirals of armor (at most) where the break actually is. You'd have to have a LOT of breaks or remove the bond wire completely for it to become ineffective.

 

[templdl]

Re: Creative Technology

tonyi, I believe the NEC is still in transition as it has always been and will continue to be as safety issues are recognized and appreciated.

(I always pull gnd, but its not required unless there's more than 6' in a run).

As an example you pull a ground even though you don't have to because you have recognized that the ground that you have pulled is more reliable.

 

[tonyi]

Re: Creative Technology

Originally posted by templdl:
As an example you pull a ground even though you don't have to because you have recognized that the ground that you have pulled is more reliable.

Individual gnd connductors aren't necessarily more reliable than an armor gnd IMO. Loose gnd splices and crimps can compromise the system just as easily as a loose AC or Flex connector. I've pulled several Romex/plastic box setups apart where the ground wires were busted off inside due to rough handling during box stuffing.

The AC cable armor/bond is more complex system than a plain wire, but I don't think its any less reliable or less safe than say MC or Romex as long as good connectors are used and they're made up tight. With a GFCI or AFCI breaker, the ability of the armor to carry heavy fault currents would become a moot point anyway.

 

[templdl]

Re: Creative Technology

tonyi,
I see your point. If the installations was done 100% correctly then no problem. I realize that if all of the connections were tight, the screw of the connecter that secures it to the BX cable exterior, and where the connector is secured to the box with a nut, the EGC would be effective. Likewise when the grounded neutral doubles as an equipment ground is a 3w, 240v appliance supply. However, there's a lot more mechnical connections with the installation of 'BX' cable which presents more opportunity to have missed a connection, that is to tighten a screw or a nut. A simple cacle in/cable out of a single junction box requires (4) mechanical electrical connections.
It may be with what we know today about the importance of the EGC that we would take more care in assuring that the installation was secure if the same installation were to be done today. But that doesn't solve the EGC problems that often exist in those existing installations.
I have discovered too many existing installations of "BX" cable where the connectors were a little loose to very loose, and where the aluminum bonding wire was not intact. These are existing installations which are maybe 30 years old and older. It's hard to determine if the connection just was not tightened during installation or if it may have loosened over time.

 

[tonyi]

Re: Creative Technology

Originally posted by templdl:
tonyi,
...and where the connector is secured to the box with a nut, the EGC would be effective...

This is why on new AC work I generally don't use connectors that need a locknut unless its a 90 degree situation and I've got no choice, or those ultra sleazy (IMO) snapin-pushin things that use the little springy fingers to hold the cable and the connector to the box...those things scare the hell out of me. I like connectors that look like this:

 

[templdl]

Re: Creative Technology

New products are great because they recognize the deficiencies in older products. What bennie and I were discussing is that grounding and bonding has been recognized as being much more important than it was in the past. Old techniques are prone to failure. With todays requirements and products the installations are much safer as the picture of the product you poster illustrates.