Code related questions


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Old 03-16-07, 06:34 PM
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Angry Code related questions

A friend of mine submitted a permit request for building a sunroom.
The local township raised a couple of questions regarding the electrical mapping. Some of them are quite obvious, but we do not understand the following two.

1. The amount of free conductors at front of box.
2. The amount of jackets within the box.

What box they refer to? Outlet box?, what are free conductors and jackets?

Thank you.
 
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Old 03-16-07, 06:45 PM
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There needs to be a minimum of 1/4" of NM cable jacket (sheathing) within the box. Meaning don't strip too much sheathing off the cable so that only the conductors are entering the box.

Free conductor length is the amount of wire in the box. This must be minimum of 6" from where the sheathing is stripped off and at the same time no less than 3" outside the box opening.

This being said, they actually brought these points up during a plan review??? What is up with that? They want to know that you plan to do this?
Heck, they could also cite about 10,000 other code issues that you must plan to do.
 
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Old 03-16-07, 08:13 PM
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Are these politicians or technicians? Or maybe politicians pretending to be technicians???
 
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Old 03-16-07, 08:26 PM
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Thank you. You both are right. They brought the issue while reviewing the plan. It might be better for us to know beforehand than to redo it during the project.
I still does not quite understand the word jacket. It is not clothing, does it mean how many lines get into the box?

After digesting Speedy's reply, I began to understand. Cable Jacket is the plastic (vinyle) wrapping outside the Romax cable. It should not be stripped too
hard. As for the free conductor length, I found the answer also at NEC forum that

300.14 Length of Free Conductors at Outlets, Junctions, and Switch Points should be at least 150 mm (6 in.) of free conductor, measured from the point in the box where it emerges from its raceway or cable sheath,
 

Last edited by lzhang; 03-16-07 at 08:42 PM.
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Old 03-17-07, 05:00 AM
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To be frank, this is stuff you should already know BEFORE doing any electrical work. These are "Electric 101" basics.

This is why I am surprised they even bring it up at a plan review. I guess your town gets a LOT of homeowners/handymen doing their own work or this would not even be an issue.
 

Last edited by Speedy Petey; 03-17-07 at 05:57 AM.
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Old 03-17-07, 05:27 AM
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It sounds to me like these items are from thier list of common recient violations. It is actually nice of them to warn you ahead of time.
 
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Old 03-18-07, 03:35 PM
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I quite agree with you. It is better to know before hand. Thank you all.
 
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Old 03-18-07, 03:57 PM
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Here is my take on this, even though I am not licensed and you can take this with a grain of salt:

*I* think they were satisfied with the "map".

*I* think they feel that many people know how to connect wires to outlets and switches.

*I* think that THEY think that some people who think they can wire switches and outlets might not know the rule about how much wire to have in the box.

When I did MY first outlet and switch, I never gave it a thought as to some need for how much wire you had in there. And this isn't going to start a fire just because you don't know that.

But I have had to replace outlets that are from some millenium out of the past where I have had to work on my back, practically, on baseboard outlets on the old 2-wire system where there wasn't hardly enough wire to pull the outlet away from the box! Aaargh! It is if the electricians back then thought they'd save wire by first wiring up the outlet and then pullking the wire in the wall back into the wall to save wire!..not thinking that someone down the road might have to change out the outlet or switch.
 
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Old 03-18-07, 05:38 PM
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Originally Posted by DaVeBoy
When I did MY first outlet and switch, I never gave it a thought as to some need for how much wire you had in there. And this isn't going to start a fire just because you don't know that.
For a single outlet box, can we put into 3 wires, or 3 connections as the maximum? For ceiling light fixture box, can we have 4 circuits get into?

Thanks
 
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Old 03-18-07, 05:50 PM
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lzhang, the answer to all of your questions is "maybe". The rules are not as simple as you present them. We need all the details to know. We need to know what's in the box (e.g., a duplex receptacle), how many cubic inches the box is (even within single-gang boxes, they come in a lot of different sizes), what type of box (metal or plastic), how many wires, the function of each wire (hot, neutral, grounding), and the gauge of each wire (#12, #14, ...).
 
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Old 03-19-07, 11:36 AM
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Yes, there are many possibilities.

For example, we all buy the smallest plastic boxes from for NM Romex cables with hot, neutral & grounding:

1. a 15 Amp duplex receptacle using all #14/2 cables
2. a 20 Amp duplex receptacle using all #12/2 cables
3. a single switch using all #14/2 cables
4. a 3 way switch using all #14/2 cables

5. a plastic light fixture box with a string cord using all #14/2 cables

Sorry. I do not know their cubic inches. Thank you, again.
 
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Old 03-19-07, 12:05 PM
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We can do nothing without the cubic inches. It'll be stamped somewhere on the box. Let us know.

And we need a real number, not just the word "all".

And from now on, always buy the biggest boxes you can find.

P.S. If you want to know the algorithm in general, and not just the answer for particular situations, pick up a book on home wiring. Almost all of them tell you how to calculate how much can be put into one box.
 
 

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