Behavior of Joule Heating in few contact points terminals and arcing

[ptonsparky]

Loose connections can cause arcing..why cant loose bus bar and chair lugs contacts (with only few contact points)?

That probably started as a glowing connection. No spark.

 

[kwired]

Loose connections can cause arcing..why cant loose bus bar and chair lugs contacts (with only few contact points)?

High resistance for the amount of current is the key. In that video clip, weak contact ultimately caused heating and made things worse, as Tom mentioned initially it probably was just increased heat at the connection, eventually things got worse to create what is there now. Same can happen with the chair lugs. If not sufficient contact surface for the current being drawn, heating will occur and that heating will eventually cause more deterioration of the connection.

 

[ptonsparky]

High resistance for the amount of current is the key. In that video clip, weak contact ultimately caused heating and made things worse, as Tom mentioned initially it probably was just increased heat at the connection, eventually things got worse to create what is there now. Same can happen with the chair lugs. If not sufficient contact surface for the current being drawn, heating will occur and that heating will eventually cause more deterioration of the connection.

Look closely...looks like aluminum wiring. Suppose the device was rated for Al? Torqued?

I know, I’m just twisting the knife.:huh:.

 

[kwired]

Look closely...looks like aluminum wiring. Suppose the device was rated for Al? Torqued?

I know, I’m just twisting the knife.:huh:.

Maybe, EGC looks too small to be 12 AWG to me though. Aluminum isn't supposed to be smaller than 12 AWG, don't know if there was any out there anyway or not.

 

[ptonsparky]

Maybe. Plus it's hard to torque those good stab in connections.

 

[tersh]

High resistance for the amount of current is the key. In that video clip, weak contact ultimately caused heating and made things worse, as Tom mentioned initially it probably was just increased heat at the connection, eventually things got worse to create what is there now. Same can happen with the chair lugs. If not sufficient contact surface for the current being drawn, heating will occur and that heating will eventually cause more deterioration of the connection.

Remember we have AFCI (Arc Fault Circuit Interrupter) precisely to avoid arc related fires. So arc forms when there is not sufficient wiring area for the current and there is a gap?

Also do you trust plastic screw nuts? Here in youtube I saw there is this loose wiring inside the wire nuts and even though AWG 14 can take the current with the 15A outlet. It burns due to the arc alone forming?

 

[hbiss]

My head hurts!!

Do you expect us to rehash all we have written about AFCIs and glowing connections for your "education"?? It's all there, just do a search!

And you ask professionals if they trust wire nuts? hmy:

-Hal

 

[tersh]

I've actually been reading a lot about this in the internet. It's something we were not taught in engineering 25 years ago. Field experience is different from textbook experience.

So glowing connections is cause of fire and takes time to develope by oxidation.

I'm goggling about instances where new connections were done temporary and the arcing (without oxidation) is enough to suddenly melt the wire nuts without even any oxidation forming?

 

[hbiss]

This is another witch hunt of yours because you have no understanding.

I'm Googling about instances where new connections were done temporary and the arcing (without oxidation) is enough to suddenly melt the wire nuts without even any oxidation forming?

Sure, if someone is that stupid to abuse them by not installing them properly what do you think is going to happen?

Wire nuts are the standard that we have used for almost 100 years. They have evolved and improved over that time but basically are the same. When installed properly I would say that they have a zero percent failure rate, and as long as the connection isn't compromised by corrosion or oxidation (where some other method should be used), will remain that way.

That video is just some of the garbage out there to fan the emotions of the general public by the pro AFCI people. That splice wasn't even made up, rather just two stripped conductor ends loosely stuck in a wire nut. Then the circuit was overloaded and when the splice got hot he threw saw dust on it. Gee, why did it burn?:roll: He says that the initial arcing would have triggered an AFCI which would have prevented the "fire". So why didn't he repeat the experiment with an AFCI in the circuit to prove that? Because the only thing that would prove is that they don't work.

-Hal

 

[tersh]

Ok. So arcing by itself is not harmful. It can only cause harm if there is oxidation and resistive heating that can ignite the surrounding of the box, etc.

The arc spark is not enough to heat the surrounding and cause fire, right?

Anyway. For Europeans. How did you setup your whole house AFCI protection? In the US, AFCI breaker is only mostly 15A and it's mostly outlets too. There is no 60A breaker version, so it's more difficult to setup a whole house AFCI protection.

For the Americans. So you have two outlets in series. One a GFCI outlet and an AFCI outlet? So if you don't use AFCI breaker, you install an AFCI outlet, and connect another GFCI outlet in series to it? Better would be combined AFCI/GFCI outlet.

For the rest of the world with 240v electricity. Please share how you setup a whole house AFCI protection.

 

[hbiss]

For Europeans. How did you setup your whole house AFCI protection?

Europeans don't use AFCIs. They use RCDs. AFCI is an American boondoggle.

Let me be clear here, and this is not just opinion. It's the consensus of electrical professionals who have experience with them and know the story behind them. AFCIs are one of the biggest frauds on the American people that there ever was.

Over 20 years ago manufacturers convinced the NEC that they had this product that will save lives and got AFCIs written into the Code so that we must use them. Then they got UL to come up with a bogus test involving neon sign transformers to say that they work. They didn't work back then and over twenty years later they still don't work. In all that time it's never been proven that AFCI technology has saved even one life. But the manufacturers are making money hand over fist because whatever they make we have to use.

Some states and jurisdictions have removed the requirement for AFCIs from the rest of the NEC. Class action lawsuits have been proposed, but the manufacturers have more and better lawyers who they will put to work because if they lose somebody will go out of business.

So suffice it to say I would advise you to not even go down that road because you don't appear to know the first thing about AFCIs.

-Hal

 

[mbrooke]

Ok. So arcing by itself is not harmful. It can only cause harm if there is oxidation and resistive heating that can ignite the surrounding of the box, etc.

The arc spark is not enough to heat the surrounding and cause fire, right?

Anyway. For Europeans. How did you setup your whole house AFCI protection? In the US, AFCI breaker is only mostly 15A and it's mostly outlets too. There is no 60A breaker version, so it's more difficult to setup a whole house AFCI protection.

For the Americans. So you have two outlets in series. One a GFCI outlet and an AFCI outlet? So if you don't use AFCI breaker, you install an AFCI outlet, and connect another GFCI outlet in series to it? Better would be combined AFCI/GFCI outlet.

For the rest of the world with 240v electricity. Please share how you setup a whole house AFCI protection.

Arcing by itself is can be very dangerous, however at 120 volts it is very difficult if not impossible to sustain an arc.

 

[tersh]

We're supposed to tourqe everything to manufacturers spec's , an old issue recently brought to the forefront of the NEC>>>>

110.14....


The truth being that the larger equipment is usually addressed before smaller terminations.

Our (at least my turf) AHJ's normally ask to see toolage, and leave it at that....

As an aside to this, much larger equipment instructs an annual retourqe , wich is seldom (if ever) done...


~RJ~

I'd like to inquire about using Torque screw drivers in breakers and panels. I read that:

https://www.ecmweb.com/contractor/do-you-have-calibrated-arm

"Torque screwdrivers are available, but very few electricians use them. Electricians indicated they were more likely to use a torque wrench on larger conductors, such as those found on
transformers or switchboards, but not on branch circuit connections. Only 36 of the 402 participants indicated they always use a torque wrench or screwdriver to make electrical connections, while 247 answered they sometimes use a torque wrench or screwdriver to make electrical connections."

Is it really true few electricians use them? In my country. I inquired all stores. They only have torque wrench for car wheels. No one carried any torque screwdrivers and no one use it.

But in my Siemens main panel with all GFCI breakers. I saw this:

In the main breaker. I saw the torque is 55 lb-in. In the individual breakers. It's 20 lb-in for AWG 10, also same for the Schneider Din rail breakers.

I plan to purchase a unit or sample to see how strong is 55 lb-in or 20 lb-in. Torque screwdrivers are selling in amazon for $200. May I know what is the best brand and model available there. It's a one time purchase only so need to make it right first and last time. I will also empower my electricians to use it all existing installations and recalibration to exact manufacturer's torques specifications.


​

 

[ptonsparky]

The damage I see from poorly made connections to a device or a wire connector have always been contained within the box.

We looked at one a few years ago where the power was still on to the 4” square box. No recognizable device, or connector was left, every thing was charred. The Cable jackets were intact and functional after they left the box. No damage outside of the box had occurred.

The basement was getting a remodel by the proud owners son in law, but they were having an issue with his new wiring in a basement bedroom. I was asked to investigate that while I was there. I showed her the red wire connector of the open splice pushed up against a 2x4 by the Sheetrock. (I happened to see the red at the joint of the untaped rock). I took her back to the previous room and explained how that box had saved her house and the importance of them. She declined my offer of exposing all the new wiring to investigate and fix the bedroom problem.

Summary, you can’t fix stupid.

 

[ptonsparky]

I'd like to inquire about using Torque screw drivers in breakers and panels. I read that:

https://www.ecmweb.com/contractor/do-you-have-calibrated-arm

"Torque screwdrivers are available, but very few electricians use them. Electricians indicated they were more likely to use a torque wrench on larger conductors, such as those found on
transformers or switchboards, but not on branch circuit connections. Only 36 of the 402 participants indicated they always use a torque wrench or screwdriver to make electrical connections, while 247 answered they sometimes use a torque wrench or screwdriver to make electrical connections."

Is it really true few electricians use them? In my country. I inquired all stores. They only have torque wrench for car wheels. No one carried any torque screwdrivers and no one use it.

But in my Siemens main panel with all GFCI breakers. I saw this:

In the main breaker. I saw the torque is 55 lb-in. In the individual breakers. It's 20 lb-in for AWG 10, also same for the Schneider Din rail breakers.

I plan to purchase a unit or sample to see how strong is 55 lb-in or 20 lb-in. Torque screwdrivers are selling in amazon for $200. May I know what is the best brand and model available there. It's a one time purchase only so need to make it right first and last time. I will also empower my electricians to use it all existing installations and recalibration to exact manufacturer's torques specifications.


​

Thats a step. The Klein screwdriver I purchased 20 years or so ago had a wide range of settings. A different brand newer driver require the purchase of two to get the ranges we commonly encounter.

My nephew works and teaches at a nuclear power plant. They test the torque settings of each tool before it is checked out of the tool crib. Each and every time.

 

[tersh]

Thats a step. The Klein screwdriver I purchased 20 years or so ago had a wide range of settings. A different brand newer driver require the purchase of two to get the ranges we commonly encounter.

My nephew works and teaches at a nuclear power plant. They test the torque settings of each tool before it is checked out of the tool crib. Each and every time.

you mean this $1648 Master Electrician Klein Torque set?

https://www.amazon.com/Electricians...2192&sr=8-9&keywords=Klein+torque+screwdriver

It's so expensive, lol. My maximum budget is $200.

What is the electrician favorite budget model? Many torque screwdrivers in amazon are for bicycles and other stuff. Which is the one for electrician use?

This $59 model looks good https://www.amazon.com/Products-Tor...50227881&sr=8-20&keywords=torque+screwdrivers

it has 2 to 8 N.m setting. Note din rail breakers use metric torque setting. The Schneider din rail C120N has 3.5 N.m which converts to about 30 lb in. (why do din rail breakers take more torque than the 20 lb in in plug in breakers?) 8 N.m is about 70 lb. in. Is it a electrician friendly tool? Will let my electrician use it and to show it to electrical contractors.

Most important is any torque screwdriver for electrical use must be Milspec accurate.

 

[romex jockey]

My nephew works and teaches at a nuclear power plant. They test the torque settings of each tool before it is checked out of the tool crib. Each and every time.

One of our ahj's ran w/that issue.....because we all stampeeded out and bought torque toolage >>>


https://www.homedepot.com/p/Capri-T...PIPHorizontal2_rr-_-204772217-_-206981635-_-N

meant little if they owner did not follow the certification ,usually indicating annual recalbration

a few local sparks found that there were little to few authorized entities available , and that the expense(s) involved resluted in a new purchase looking the economical route.

I can't fault my ahj , but i can say it's another good intent paving the road to perdition

As an aside , i found that installing the specified tourqe left me wanting to tighten things more than required. Apparently i had unwittingly overtouqued most installs as routine. So i have to ask, how have i harmed those many decades or work doing so? The spectre of liability robbing many an EC from a good nights sleep....:?

Further, there exists on the electrical market today many speed related electrical goods employing quick connect , or tool-less connections.

from devices....

lighting (recessed can JB)....

connectables.....

SQ D ,in the past also manufatured a 'backstab' style ocpd.

So it occurs to me that, i could wire the lions share of any given job w/o having to touque anything due to these products

~RJ~

 

[kwired]

One of our ahj's ran w/that issue.....because we all stampeeded out and bought torque toolage >>>


https://www.homedepot.com/p/Capri-T...PIPHorizontal2_rr-_-204772217-_-206981635-_-N

meant little if they owner did not follow the certification ,usually indicating annual recalbration

a few local sparks found that there were little to few authorized entities available , and that the expense(s) involved resluted in a new purchase looking the economical route.

I can't fault my ahj , but i can say it's another good intent paving the road to perdition

As an aside , i found that installing the specified tourqe left me wanting to tighten things more than required. Apparently i had unwittingly overtouqued most installs as routine. So i have to ask, how have i harmed those many decades or work doing so? The spectre of liability robbing many an EC from a good nights sleep....:?

Further, there exists on the electrical market today many speed related electrical goods employing quick connect , or tool-less connections.

from devices....

lighting (recessed can JB)....

connectables.....

SQ D ,in the past also manufatured a 'backstab' style ocpd.

So it occurs to me that, i could wire the lions share of any given job w/o having to touque anything due to these products

~RJ~

That receptacle pictured still depends on screw pressure on the clamp to make a secure connection, it is not one where you just push conductor into back of receptacle and the connection is done.

 

[kwired]

Remember we have AFCI (Arc Fault Circuit Interrupter) precisely to avoid arc related fires. So arc forms when there is not sufficient wiring area for the current and there is a gap?

Also do you trust plastic screw nuts? Here in youtube I saw there is this loose wiring inside the wire nuts and even though AWG 14 can take the current with the 15A outlet. It burns due to the arc alone forming?

Any connection has a higher possibility of failure if not used properly.

"Wire nuts" have a metallic spring coil inside that is what secures the conductors. Though they are somewhat a simple design, they still have instructions and list of combinations of conductors they are intended to be used with. Improper alignment of conductors before twisting the connector on can result in poor connection on one or more conductors. Experienced users, in particular those that have learned because of call backs because of failed connections, learn to at very least pull on each individual conductor after installing the connector, if any of them pull out - they weren't in very good in the first place and would have possibly failed if you hadn't checked.

The plastic cover is nothing more than an insulator for the connector inside of it, plus it's size and shape help to give some leverage when twisting the entire assembly onto the conductors.

 

[tersh]

earlier today i read that overtightening screws has effects of undertightening in long term because when the conductor vibrates it can become damaged and loosen. I couldn't find the information again after searching for half hour so if you know the details, please elaborate how true it is. This was what concerned me that only a torque wrench is worry free to avoid oxidation and burning in future. But there are different models of torque wrench. The good one is one where you can hear an obvious click. So what brand and model is that?