Comments?

- ThinkGood

Think Good:
Another good reason not to "back stab" receptacles.
Looking close...is that a little bit of green corrosion on the black conductor??

Looks like THW insulation, metal box, so a guess it's BX. Self-grounding receptacle (look at the top yoke), appears to be "newer" as it's probably been replaced.
Thinking further, the wire may have been bad, or starting when the device was replaced. Finally, the circuit may be over-fused, and/or having a "heavy" load on for extended time. (Electric heater, cooking appliances, etc)

Lastly, also could be excessive "heat" from the male attachment plug.
John

I know that UL and ANSI and others work on putting the standards (minimums) together, but the guys in the field run into this all the time. I think it is time for this standard to be revisited and revised (upwards).

Pierre

Hi, John.
Long time...etc.

I can tell you do this for a living!

This is from a neighbor's kitchen that was recently redone.

The photo didn't show the green very well, but the hot did have green on it.

The conductors were from BX. It's too late to find the conductors to check, but the insulation was thicker than what is found in Romex (Is that THHN?). There was no grounding conductor in the cable. Does that confirm THW?

P. S. If this was not in an area being renovated, assuming the overload protection was the correct rating and the device was replaced with a GFCI (as this was in a kitchen), would the BX be considered safe to use? (Does that browned area cause the whole run to be questionable?)

P. P. S. How reliable is a ground on a "self-grounding" device? The box was somewhat corroded.

Pierre:
Do you mean the 75ºC rating?

[This message has been edited by ThinkGood (edited 06-27-2003).]

Hello Thinkgood

I meant the 'backstabbing', what UL and manufacturers call 'pushin'. I get calls all the time relating to this. It is funny how all say they would never do this, who is doing it then?
BTW - I live by the Tappen Zee Bridge, is that pretty close to you?

Pierre

ThinkGood,
Mama's got something good cookin' there, mate!.
It's sure been hot in there.

Got to love those backstabbers.
The insulation in the cable is most likely type TW (60°C). Type THW has a much thicker insulation, and was generally used in conduit, rather than cable.
Would the green patina be from the conductor getting wet??...S

Steve,
What is back-stabbing, in relation to this posting?

Trumpy, "back stabbing" is when the wire is inserted into a hole in the back of the device. The electrical continuity between the conductor and the device is derived by a springy(?) clip that pushes against the wire. The connection is no where close to being as good, as the wire being under a screw. The initial result of course is heat build-up.

Trumpy,

I think it's a similar connection to what the Wago connectors use if you are familiar with those.

Bill

Early frost-free refrigerators and 94¢ 'poke-wired' receptacles behind them were a bad combination.

Listings changed a while back to #14 only being able to be 'backstabbed' into devices, (where it had been #12 also)

somewhere a rationale exists for this, yet to me it must be inclusive of some study resulting in less of a body count with #14 installs

Q~ is such a cheesball design allowed elsewhere in the world?

just wondering...~S

Guys:
Just a quick note.
Came across a "homeowner special" last week with my AHJ hat on...
Finished basement, no permits at original job; owner selling house; needed to get a permit and inspection. Had the H/O pull all the plates and devices to "see" the wiring. Damn if this guy didn't backstab #12 (NMC), and to top it off, he managed to backstab #12 THHN stranded from some wiremold runs. Couldn't take a pic, but it was close to TG's fry job.

TG: I hope you get the drift; a "bad" or questionable termination/connection WILL eventually show it's face. DEpendent on the load, and the duty cycle, it may be real soon, or a long time.

IMHO, If the area was being renovated, and the original cable passed muster, then it could be re-used. It must be properly protected by a CB. There are opinions as to doing this, but the "rehab" code in NJ allows it, to an extent. It is not a "standard" practice with most ECs to re-use old cable; most times in a kitchen reno, the "old" is #14, and the "new" has to be #12.

A penny saved sometimes, can lead to many dollars spent in the future.

I'm gettin of my soap box, and back to work.
John

We don't use it here in the U.K. -- All receptacle and switch terminals are screw types, although they use a different arrangement to American types. (They're more like the way you would place a conductor under the end of a screw in a neutral bar rather than being wrapped around under the head.)

The "push-in" contacts are found in some appliances though, such as the trigger switch on power tools.

Paul:
I have to ask; the devices that you described, may be "available" here also, in our face and voltage configerations.
Are you refering to the conductor going "straight" into a "hole" at the back of the device, and then you tighten the screw which compresses the "hole" tight??

That may be a very poor choice of words, but I call those devices "spec" grade. They are available here, and they are more costly than the binding screw post, and the back stab devices. I like them, my men like them, and we use them most of the time. Ya get what ya pay for.
John

Those are the good ones. The crappy ones have a little spring clip inside to grab the wire. The screws on the side don't do anything here. Imagine the small amount of contact from the wire to the device, similar to that if a pair of wires are touching in one spot only. That small contact area can get really hot. Also makes for lights dimming and staying dim when a heavy load switches on.

That sounds a fair description. Here's a typical device:



You can't see the line & neutral terminals for all the plastic surround, but they're the same type as the exposed grounding terminal.

Some of the more expensive versions have a "square" hole and instead of the end of the screw itself clamping the conductor in place, it compresses the wire(s) under a small square plate.

(No, the plate on the device isn't actually blue, it's just poor color rendition!)

[This message has been edited by pauluk (edited 07-02-2003).]

This is what I've learned from a couple of wiring devices catalogs.

The devices that allow the stripped solid wire to be poked in the hole and held in place with a spring-loaded contact are called "BACK STAB"

The devices that clamp the wire in place under a screw are called "BACK WIRE".

I really really like back-wire devices. Bending hooks and looping over a terminal screws can sometimes be a pain....

[This message has been edited by SvenNYC (edited 07-02-2003).]

Paul & Sven:
It all boils down to $$$$$
The "good ones"; "Backwire" "Spec" are pricier than the el-cheapo's, but IMHO well worth the additional cost. (Receptacles and switches)

Paul:
If yaou look at TG's photo on the top of this thread, our devices look like that; you insert the stripped conductor & tighten the screws, no looping required, although some die hards still loop them.

I gave up trying to send the picture. Maybe someday, time permitting, I'll master the digital camera, CD, and e-mail thing.
John

I have a box of hospital-grade Hubbell 5-15 receptacles which appear to have the same facility: Insert wire through hole on back, then the screw tightens a small clamp onto the conductor.

It's still a somewhat different design to the British equivalent though. These Hubbell devices will accept only one conductor per terminal. The British terminals pictured above will take two or three.