>Apprentice<In school< gonna try to do a 365 electrical question thread.

[pancake808]

I am a 2nd year apprentice. I work my behind off @ work and in the class room. I take extra time to study the mike holt videos/work sheets and Follow the NEC.
I am going to post a question a day on certain things I run into at work or in the class room hence the "365". My teacher this year prefers to show us videos of his vacations rather then teach us anything.

Im still a little green but, I am not a dummy. Please correct me if I'm wrong and go into detail if needed on complex subjects. Please include NEC code references so I may Mark them down in my NEC.

I am currently working on meter stacks, electrical room, panels,main house panels,and feeders ect for large condo development. "The Fun stuff" I got the privilege to do this due to my hard work and constant strive to be the best.

I tried to ask questions to guys at work but they look at me like I'm speaking Chinese.



Please help me reach my goal thnx.

 

[jumper]

Welcome,

As a general rule we prefer that you post your question and your answer, including where you got it, and then members may decide to help you out.

We are disinclined to directly provide answers to homework questions. We prefer that you try and answer them first. You will learn more that way.

 

[pancake808]

I will NOT post any homework questions on here, that would be lame:happysad:. Just trying to sharpen my skills. Hard to do that where I work now.

 

[John120/240]

I will NOT ........... Hard to do that where I work now.

Find a NEW employer if that is feasible. Keep your head up & forge ahead.

 

[pancake808]

cable straping

cable straping

I was working on a parallel feed on a transfer switch/gear and came across a small sticker inside the enclosure. It showed a non detail picture of the electrical bus bar with the conductors that were attached to the bus wrapped in rope? tried to find more information and only could find this below. the sticker also had this information on it.


This section states in relative part that the electrical equipment shall be marked to indicate the "type of bracing to be added to the cables routed through the switchboard between the point of entry and the incoming terminals" and the marking "shall be located adjacent to the incoming terminals."
The marking shall state the following or the equivalent: "Wrap line cables together and, if provided, tap cables together with nominal 3/8-inch nylon rope or rope having a minimum tensile strength of 2000 pounds at (1) 6 inches and 12 inches from the line terminals with five wraps and (2) every additional 6 inches with five wraps or every 1 inch with one wrap.

Any more information, pictures, and or how to wrap conductors Etc would be appreciated. I did look into my NEC and also my mike holt "understanding the NEC hand book" and didn't find anything specific on this. Once again thank you for your time.





link below



http://www.dli.mn.gov/ccld/ElectricalCodesBulletinsCables.asp
Underwriters Laboratories, Inc. Standard for Dead-Front Switchboards 891, Supplement B, contains requirements for the construction of switchboards, current transformer compartments, cable termination cabinets, and similar equipment with a maximum 100,000 ampere short-circuit current rating for which a short-circuit test may be waived.
Electrical equipment which has been tested for a rating of greater than 10,000 RMS symmetrical amperes, and which required conductor bracing to be installed during the test, must be marked in accordance with Section SB5.1 of Supplement B.
This section states in relative part that the electrical equipment shall be marked to indicate the "type of bracing to be added to the cables routed through the switchboard between the point of entry and the incoming terminals" and the marking "shall be located adjacent to the incoming terminals."
The marking shall state the following or the equivalent: "Wrap line cables together and, if provided, tap cables together with nominal 3/8-inch nylon rope or rope having a minimum tensile strength of 2000 pounds at (1) 6 inches and 12 inches from the line terminals with five wraps and (2) every additional 6 inches with five wraps or every 1 inch with one wrap." In addition, it is recommended that the manufacturer include a drawing that shows the required cable wrapping.
The purpose of the bracing is to restrain the conductors from violent movement during fault conditions. Conductors not properly braced may pull out of their terminals and cause severe destruction of the electrical equipment, which in turn could result in fire or personal injury.

• Electrical equipment that has been tested with cable bracing for a rating greater than 10,000 amperes must be marked with the cable bracing requirements
• Electrical equipment that has been tested without cable bracing for a rating greater than 10,000 amperes is not required to be marked with cable bracing requirements
• UL 891 does not require, nor does it prohibit, any marking indicating that the electrical equipment has been tested without cable bracing for use on systems with greater than 10,000 RMS symmetrical amperes available
• For all installations, electrical equipment must be marked with a short-circuit current rating that equals or exceeds the short-circuit current available at the equipment
• For electrical equipment that is not clearly marked as to whether or not cable bracing is required, contact the manufacturers representative

 

[pancake808]

Arguement at work today. back of Luminaire to jb feed through.

Arguement at work today. back of Luminaire to jb feed through.

Arguement at work today. We are mounting 4ft, single lamp,t8 luminaries in a parking area. The lights are mounted over a JB that is flush with the ceiling "JB IS encased in concrete". One guy says you can make up wires in the JB, mount the light to ceiling "not to the JB" then feed the tails through a 1/2" knock out with a pass through bushing.

Another guys says you need a 1&1/2" minimum hole in back of luminaire.

I say you need a hole big enough to access the wires/JB as stated in NEC 410.24b as these light are mounted permanently. My question is the size of the hole up to the installer? Obviously big enough to access wires easily and still keep the installation safe and not ruin the light housing. I also looked around in Nec 314 area and couldn't find anything.

thanks, Aaron

 

[jumper]

The size of the access hole is not defined directly as to its dimensions.

410.24 Connection of Electric-Discharge and LED Luminaires.
(B) Access to Boxes. Electric-discharge and LED luminaires
surface mounted over concealed outlet, pull, or junction boxes
and designed not to be supported solely by the outlet box shall
be provided with suitable openings in the back of the luminaire
to provide access to the wiring in the box.

 

[K8MHZ]

Aaron,

It's GREAT that you came up with this idea. May I caution you (you may already know) not to get involved in the 'arguments' at work. There is just no convincing some people. Now, getting into discussions is different animal. I have seen guys argue about code stuff and actually get mad at each other about it. On the other hand, when I was an apprentice we had great instructors and the journeymen knew it. Many times a discussion at work would lead to me being asked to bring the issue up at school. Sometimes that led to a discussion about it at school.

When I was in school, our 2nd year was the hardest for most. That was the year we were doing lots of math and theory stuff. I was good in math and had been playing with electrical stuff since I was a kid, so 2nd year was actually one of my favorites.

I can tell you are serious about your apprenticeship and I commend you for that. Here is one bit of advice that I learned the hard way. This goes for pretty much all tests.

There will be times when the right answer and the correct answer differ. Your goal in test taking is to figure out what answer the author of the test expects as a correct answer. I pretty much mastered that, but find the fact that such questions and answers to be counter-productive. Really, when you think about it, second guessing an author in order to come up with the best wrong answer is exactly what occurs.

Now, this depends on your personality. I always brought the teacher to task when these questions came up. A couple times the teaching text was actually changed based upon my challenging of a test question. Sometimes I would write little notes on my tests like 'I know this is the answer you want, but it's not correct'. Adding a smiley sometimes helped.

I hope you are keeping a diary of sorts with each question and at least a summary of the answers you get. That would be a good read for many in the trade.

 

[mbrooke]

Ask what you need, I will help you as best I can. The education system sucks... its for the lowest common denominator. Fortunately you are in a places with exceptionally talented people, and I know many of them enjoy helping others.

 

[iwire]

Caution, unsolicited advice to follow.


Drop the <, >, @ and any other text / Facebook stuff in any work related communications.

 

[augie47]

Pancake:
A suggestion. If you follow you desire to post a question a day, this thread, with your questions and Forum answers and comments, is going to become laborious.
I would think the results will be far better for all if you simply start a new thread with each question placing it in the appropriate Forum with a header providing some clue as to the nature of the question.
There are a lot of folks with a ton of knowledge here but not all of them are going to scroll thru multiple pages or even look at a thread that does not have a header in line with their interest or skill.
Were I not a moderator I probably would not have looked at this thread today as there was little in the header to catch my eye.

It would also be a great idea to edit your profile to add which Code cycle is being enforced in your area.
Often the answers to your question will vary depending on the Code cycle in place.

 

[pancake808]

new threads.

new threads.

I will start posting in proper areas, as asked by admins. Thanks for everyones help. I will still post questions, but in proper areas of forum.