I see that Anchorage has a lower limit of 4000 hrs as a Home only Electrician or under 200 Amps. Is this License as a journeymen all across the US?
I found this to be interesting!!!
http://www.iaei.org/magazine/1999/03/electrical-inspector-certification-program-in-the-united-states/
Crap again there is no one in SSM On.
http://www.iaei.org/certifications/list-of-canadian-cei-inv-investigation-inspectors/
But we do have an Installer that I have as contact.
http://www.iaei.org/certifications/list-of-canadian-cei-el-electrical-installation-inspectors/
Rob,
I am really rusty with this math but I come up with 200 amps at 120 volts being about 7 thousand BTU/H. The flame from a Bic lighter for one second will equal about one BTU.
Copper melts at around 1900 degrees F.
Now to the real world; If anyone has ever cut through a live cable they know what happened to their cutter, a hole was left in their tool but the cable did not curl into the shape of a sine wave. Nothing pulled loose at a termination point.
The clearing time of a 15 or 20 amp circuit breaker used in residential wiring systems would never let 200 amps pass for any length of time, just as the breaker tripping when the cable was cut. Under a dead short or ground fault most residential circuit breakers will clear their self in about .033 seconds or about two sine waves.
Jump into large overcurrent devices such as 2000 amp then there will be a strong pull on the termination points in the event of a short or ground fault. Roping of the conductors is strongly suggested. I have even did this roping on large motors (800 HP) at water treatment plants.
Now back to the subject matter of securing cables lying across ceiling joist. In 44 years of installing NM cable in attic spaces I don’t ever remember stapling them unless I was in the area of access to the attic space, the allowance of not stapling these cables in studs or when being fished in the wall speaks for itself.
Granted I don’t leave extra cable lying around such as was in the picture but instead the cables are pulled tight from place to place. I do staple cables when installed as shown in the third picture but doing a home inspection I would not call out the cables just lying there.
The Home Inspector is not a Code Enforcement Official but instead is looking for safety issues such as no bonding around hydro massage tubs, lack of GFCI, open joints, missing covers, and such. In most areas around the country the Home Inspector is not allowed to point out code violations unless they hold an electrical license.
The 200 amps comes from something we learned in apprentice school back in the 80’s. I’m unsure of it’s accuracy.
I know I beat this drum every time (and I have refrained until now :D), but I always pull covers when I see metal j-boxes used on NMC. 9 times out of 10 there will be no bond to the egc.
So besides securing the box, I will be suggesting that the bond be established or the metal-box be replaced with a plastic-box.
Good point Jeff. I once had an electrical inspector open a 1900 box which contained an A/C service receptacle in a dirty attic to check for the bonding jumper. :roll:
You got me Robert - I don’t know if I understand where you’re going…
My dear friend I would suppose that my calculation would be about as accurate as using a sewing thimble to measure out one gallon of water. I to remember something along this line back when I was in Tech school a few years before you.
How many years before you, well, let me say that we used a slide rule instead of the new fang dangled calculators. Our instructor used one of them Chinese button calculators. Hand held calculators cost too much back then.
You suggest many things that concern me.
First, you state you are an instructor. As such, do you suggest that doing something wrong for 44 years makes it correct? NM cable should always be secured when ran across joists in an attic. Always. It is mandatory. Your attempt to justify this by mentioning the exception for installations in finished walls is unprofessional. This is not in a finished wall. Exceptions are exceptions and in no way justify failure to adhere to applicable code articles. I can not believe you as an instructor would suggest this.
Next, I did not say cables under fault would pull loose or “curl up” as you claim. I stated fault currents will place a strain on the terminations and the cable WILL ATTEMPT TO take the shape of a sine wave.
Also, you mention clearance times for a 20 amp breaker not allowing large fault currents to pass. In your statement immediately proceeding this you mention cutting an energized conductor and the resulting hole it creates in the tool. Interesting you mention that because those two statements are direct contradictions. I also use this example of cutting into an energized conductor when I am teaching and it proves that your statement regarding low fault currents on a 20 amp breaker is certainly incorrect.
Sublimation is the correct term. Sublimation occurs when matter is changed from a solid state to a vapor without first changing into a liquid. It takes an immense amount of energy to accomplish. Basically, you are boiling a solid into a gas WITHOUT it melting first. When an energized conductor is cut, the cutting edge is instantly vaporized and results in the hole that is formed. Keep in mind this is tool steel no less. THink about this. Think how hard it would be to instantly turn ice into steam. Now we are talking about turning tool steel into vapor instantly. There is far more current involved than 200 amps. If it is really necessary, I can calculate it, but I hope that by now you are convinced. If not, toss your linemans in a pan on the stove and see how long it takes to boil them.
You are correct that home inspectors are not code inspectors, but we are liable for errors and ommissions.
I am greatly concerned when individuals claim professional competency and yet their statements suggest other wise.
Your signature says you are an instructor. Are you an electrical instructor?
Sorry for the confusion I was merely stating that I even had an electrical inspector open up a 1900 box with NM cable to see if the bonding jumper was installed to the box.
I’m agree with you that they’re required but often omitted.
For 12 years now I have stood at the front with marker and text book in hand.
Now let me see if I understand what you are presenting. Are you saying that the cutters turn to gas from a solid or are you saying they are melted just as a rod in the stinger of a welder?
Copper melts at a lower temperature than Steel (copper 1900 and boils at 2300, steel 2800) and when copper turns to gas it expands about 67000 times its size. This would mean that when this steel of the cutters turned to a liquid the area of coverage of a #14 conductor would be 931 square inches or it would reach out to a distance of 30 inches. Why are we not being burned by this copper?
No my friend not thousands of amps. The breaker on a 15 amp circuit would open at 90 amps in .033 seconds. Most breakers in a residential panel would come apart with thousands of amps flowing through them for even a millisecond.
Here is a good place to start. At the bottom of the first page they melt a copper conductor with less than a thousand amps.
You aint gonna give it up. What is the symmetrical fault current rating of a residential breaker? Why?
Why the need for NFPA 70E? And by the way, 67000 times is exactly referenced in the training of that standard.
Was I supposed to or something?
This would depend on the type of service that was installed. Most single pole breakers used in residential will have a RMS symmetrical rating of 10,000 amps.
This is the withstand ampere rating of the device and in no way means that it is how much current it will take to cause it to open
Safety in the workplace.
Wonder if that means that I might have been involved with this book at some point in my life?
Yes this is one of the courses that I teach.
Ok guys this has been fun but we are here to learn Home Inspection Electrical Safety.
So I am in the opinion to recommend a running board up the middle and of course a “Certified Electrical Contractor” to evaluate the spaghetti factory.
What should every Inspector say in his report when they encounter this kind of work?
William,
Mr. Whitt and I have traded commentary a few times. He is a knowledgeable individual. He is an instructor. In fact, if I recall correctly, his education is aimed at those who want to become competent in the NEC or become electrical code inspectors. I believe he is recognized as a NEC authority and may be a NEC-certified instructor. Mike will need to explain it
While the discourse is entertaining, I would like for both of you to get back on point. The way I see it, and have seen it in a practical sense, many NM cables in attic spaces are simply not installed neatly, or in a “squared off” and symmetrical manner. Many cables are not fastened to joists and simply lay on top of them. J-boxes are secured to joists, either on top or along side, depending on whether there is plywood flooring installed.
It appears that staples or fasteners are required about every 4 feet (3 joists) though we rarely see this.
When I inspect, I make recommendations as a matter of good practice, and never as a code requirement. I do not determine what a violation is. I only determine what a crappy installation looks like. If joists were bored and cables fished through, I would not be concerned with any fasteners. If the cables and boxes were installed in a neat and professionally workmanlike manner, I keep that in mind throughout the inspection process.
As to copper melting, my understanding is that the temperature needed to melt a copper conductor is around 1900 degrees Fahrenheit. Copper not only efficiently conducts electricity, but conducts heat as rell. This is the reason that holding a lighter or lower-temp torch on a conductor takes a long time to melt the conductor.
In a short circuit, the breaker will trip before the conductor melts. No so, though, where higher current flow causes excessive heat. Typically, as the copper starts to super-heat, and melts away its insulation, the ignition point of things around it is less than the conductor’s melting point, which results in a fire. Even insulation around a conductor can become a reason for an electrical fire. Simply coiling an extension cord around itself and covering it with a blanket can cause a fire. MANY factors can lead to an electrical fire. I am unsure if an electrical fire could be attributed to the sloppy wiring depicted in the initial photo, as there is plenty of air circulating around each cable to allow for proper heat dissapation. Same goes for fastening the conductors to a joint.
But, for a clearer understanding of how an electrical fire can erupt and the reasons for it, check THIS out:
http://www.interfire.org/features/electric_wiring_faults.asp
Kevin, please provide me with a list of “Certified” contractors so that I may pass it out to my clients - oh, that’s right, contractors are not CERTIFIED.
Why on earth would you call for “evaluation” of this condition? Either it needs correction, or it does not need correction - IT DOES NOT NEED “EVALUATION.”
So once again, in your report you will have provided nothing to the client.
Fixed wiring on the top! Nice thanks for the link Joe.
Oh I should say that you can call a “Licensed Electrical Contractor” also as they are the same. However someone who is just “Qualified” to install may not be a choice you want to use as I have seen “Licensed Electricians” do the spaghetti thing in attacks also.
In your previous response you state:
Obviously, your first assertion above was correct. Your previous assertion was incorrect. A residential breaker CAN pass several thousand amps of current without failing. That is the purpose of the symmetrical fault current rating. I agree it does not necessarily mean that is the amount of current that is required to cause the breaker to operate. It is the amount of current the breaker can safely pass without a catastrophic failure before interrupting the event. Also, there would be absolutely no reason for the breaker to be able to withstand that much fault current if it was impossible for the system to deliver current of that magnitude as you claimed. The first 1 to 2 cycles of fault current far exceed the trip rating of the device. Also, should the breaker fail to operate, those currents will now need to exceed the time/trip characteristics of the main.
I asked about why the need for the NFPA 70E standard. Your response:
Why would we need this standard if fault currents did not reach the magnitude they do?
I also have taught this as well but I have went even further. I have developed the electrical safety programs for several companies. Part of this included work with PE’s in determining and calculating available incident energy in electrical systems throughout industrial plants. This included 13.8, 4160, 480, 240, and 120 volt systems. As you are aware, many factors either contribute to or reduce the available incident energy and typically lower voltages do not present as great of risk, but yet the risk is still there.
Please keep in mind the main reason I first responded was to ensure that inspectors who might not have a strong electrical knowledge are properly informed.
Kevin,
Call it as you see it.
If you want to recommend further evaluation, it is perfectly reasonable to say something like this:
Remember, you are being paid for your opinion. Based on your observation, the installation is an abomination. You can just say that. You can say it looks like flying monkeys did the installation.
Exactly why I was concerned. As an instructor, his assertion that not adhering to code is ok because he’s “done it for 44 years” like this is not proper or professional. In absolute total honesty, in running work and projects all over the country, I have hired VERY FEW competent eletricians.