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V=IR 10-19-2008 06:35 AM

Help w/ items in Mullin's _Wiring Residential_ book?
I am reading the 2005 edition. Pg 29 says that in circuit diagrams, "Full slashes indicate ungrounded "Hot" (or switch leg) circuit conductors, half slashes indicate grounded neutral circuit conductors."

I know that sometimes it might be drawn the opposite way; that's not my question.

In every single cable layout example in the book, they use nothing but full slashes. For example, on pg 239 when A19 enters the room, there are two full slashes. Then it continues throughout the room with nothing but full slashes. I understand that a third slash is generally the switch loop wire.

Am I missing something, or did they do all the illustrations wrong?


The book does not talk at all about taps, except to give the rather cryptic definition from NEC. Where can I learn when it is acceptable & desirable to run one?


The book has no real how-to information; for example how to physically install boxes by choosing from whatever various clips & fasteners are available; what to use to fill gaps larger than 1/8" in the mounting hole, etc. Is there another book that goes into the sort of things you need to do efficiently during a remodel?


Is there a method to figuring out the way a circuit runs so I can know which outlet to replace when adding GFCI / AFCI to a 1960's home? How can I determine that there are no circuits with their neutrals connected somewhere?


Jim Port 10-19-2008 09:30 AM

I don't have the book so I can't explain those questions.

As far as the box mounting you use whatever works for your situation. Commonly the boxes are nailed onto the sides of studs. In furred out walls you typically use a front bracket due to the depth of the wall.

Repairing the 1/8" gap around the box should not be an issue if the drywall is done correctly. I have seen drywall compound used to repair excess gaps.

Multiwire branch circuits would be able to be seen in the panel. Look for a 3 wire + ground cable, black, red, and white. The black and red should be on vertically adjacent breakers typically, depends on panel brand, so as not to overload the white.

On the issue of GFIs it might be easier to install the breakers. No need to figure out where the circuit starts and the older boxes typically are small and it is hard to fit the receptacle into them.

BeastinBlack 10-19-2008 10:59 AM

What exactly are you trying to accomplish?

Billy_Bob 10-19-2008 12:20 PM

My experience is that I learn the most be reading 3 very different books by different authors on the same subject.

With some things, I don't "get it" with the 1st, but do with the 2nd. Then with a few things I finally get it with the 3rd or from the combined information from all 3 books.

Here are a bunch of different electrical books...

As to the mechanical fastening of boxes to walls, etc., I learned a lot by having a job at a hardware store when I was in high school - I learned all about the various fasteners, drills, tools, etc. Then working construction jobs when I was younger, I learned a lot from the other guys. Also they would order certain fasteners which you don't see in a hardware store, so I learned there are a lot more things out there than what is available in a hardware store - need to go to an electrical supply for example.

As for you learning this stuff, there are a lot of people on the internet who have this experience and knowledge. I would suggest asking specific questions for something like "Mounting electric panel on brick wall?" and then you will get a lot of information on how this can be done in many different ways. If you combine a bunch of questions in one post, many things will not be answered.

V=IR 10-20-2008 12:07 AM

()#&$*#& -- the board software allows me to type into the quick reply box, but then erases it, telling me I have to log in again after timing out. That's defective software !!!

1) I'm trying to figure out how to correctly read circuit plans.

Either I'm missing something fundamental, or the book is consistently sloppy; so why should I trust the rest of the book?

2) I just want to understand taps for completeness sake and the book doesn't talk about them.

3) installation details -- things like: a box needs to be attached either 1/2" or 5/8" forward of the stud for gypsum, or some other thickness for paneling. So how do you do it -- do the boxes have measurment marks on their sides, or do you use a ruler, or a calibrated finger, or what? And where can I teach myself about the useful brackets etc that are not on the shelf at the big box stores?

3) GFIs -- most of my breakers are already duplexed; the box is full.

That is another thing; I want to add 50A subpanel or replace the panel. I think I have 150A -- a 50A main, three 30A to range, drier, the rec room has baseboard heat.

Had a water leak that ruined the rec room so without walls & drop ceiling I can get to everything. Might re-arrange and add outlets too. Definitely want to re-arrange the light cans. Bedroom is above, so I can trace that circuit in the overhead for GFI placement.

Most important is to add a circuit for a 2.5gal water heater for the MBR hot tap. 15A would do for a 12A dedicated circuit.

Need to have an electrician look at the feed and tell me if the POCO would have to upgrade it to get 200A. Hopefully its good for something more.

4) multiwire circuits -- that's a useful tip. But on duplexed breakers, would they have put it on the Left and Right in the same knockout (so 16 Left and 16 Right instead of 16 and 18 ?)

And how does that divide into the two circuits --

Would they have run Black-Red-White-Bare cable to some junction box and then split into two Black-White-Bare circuits? Wouldn't that be two Taps?

I would need to understand if & how a GFI onto the common neutral of such a L-N-L run would work.

5) Built in the late 1960s and the rec room finished in the 1970's. I see fibrous, black & silvery cable as well as plastic white, off white or yellow and one green coming out of the breaker box. Need to see if I can read any markings on them.

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