KNOB AND TUBE WIRING

[websparky]

Re: KNOB AND TUBE WIRING

Roger,

Please! You're embarrassing me!

Whatever I can do within my ability to help is freely offered to anyone who asks.
Thanks for your kind words.

Bennie,

Funny that you should mention Oregon.... I have kin livin' there. My lovley bride would dearly love to move there when we retire. Her mother's side of the family resides in Hillsboro, Bend and Prineville. Very beautiful part of our country!

As far as the computer stuff, I think you have figured out the most important part, making it a useful tool!

Thanks Guys,
Dave

 

[jxofaltrds]

Re: KNOB AND TUBE WIRING

Karl

Topic - National Electrical Code
Subject - Proposed Changes for the 2005 NEC Date - 05-28-2003


This is Mike Holt's May newsletter. It has the changes in Adobe.

He has a link in the newsletter.

Click here to download the Report on the actions of Code-Making Panels 1 through 20 proposals for the 2005 NEC.

The hyperlink did not paste. so you can not click on the above. Maybe someone else can paste it here.

Mike P.

[ July 15, 2003, 08:03 AM: Message edited by: jxofaltrds ]

 

[don_resqcapt19]

Re: KNOB AND TUBE WIRING

Roger,
300.3(B) says that all of the conductors of the cirucit must be in the same raceway or cable unless otherwise permitted in accordance with 300.3(B)(1) through (4). 300.3(B)(3) is a clear permission to run part of a circuit in one cable and the other part in a second cable as long as both cables enter any ferous encloure vie a single cable connector. I think this is poor code and was not permitted in the '96 code. I have not had time to look at the '99 ROP and ROC to see why this change was made.

 

[roger]

Re: KNOB AND TUBE WIRING

Don, you and I are in agreement that parts of "a" circuit,(singular) whether leg to leg, leg to grounded conductor, phase to phase, phase to neutral, or whatever, as long as we are talking "one" circuit, can be installed per 300.3(B)(3),

300.3(B)(3) is a clear permission to run part of "a" circuit in one cable and the other part in a second cable

this does not allow parts of "two" circuits to be used to create "a" circuit.

Now back to Karl's post,

What now prevents you from running "two" NM circuits to some loads and using the hot from one cable and the neutral from the other cable,

I simply don't see where permission is given to share current carrying conductors of different circuits (multiple) to make one. (singular)

Roger

[ July 15, 2003, 10:21 AM: Message edited by: roger ]

 

[karl riley]

Re: KNOB AND TUBE WIRING

Wow! A lot of discussion since I last logged in.

Roger, where does the NEC prohibit using the hot from one NM and the neutral from the other? We are saying the 1999 change allows this. You would have to quote an article which prohibits it, as did the 1996 300.3(b).

Dave and all, thanks for suggestions about downloading the 2005 stuff. Dave, actually I was primarily interested in whether anyone had proposed to change back 300.3(b) to disallow the exception for NM cable. So if you have that reference, maybe you could just tell me.

And about magnetic fields due to separating conductors of a circuit, consider this crazy fact: next month a Portland,OR software company is going to the expense of flying me from Boston to Portland and paying my fee and a hotel and a rental car so that I can trace the source of a magnetic field that is coming from a circuit in their office. The local electrician can't do it.

Now that is fine with me, since I enjoy the trouble shooting process, and I get a free August vacation (I'll take a rental car tour through Idaho before flying back). I know the cause of the field will either be from an incorrect connection of a neutral OR from a three way switch circuit done incorrectly but, now, legally.

Since I will die before too long (due to pure age) it would be nice to know that electricians start to recognize the power of magnetic fields due to separation of conductors and learn how to trouble shoot the cause.
Karl

 

[bennie]

Re: KNOB AND TUBE WIRING

Karl: I am 15 minutes from Portland, give me a call, I will buy the coffee. I will email you my cell phone number.

Note...This is number 1500, what a lot of BS

[ July 15, 2003, 11:22 AM: Message edited by: bennie ]

 

[roger]

Re: KNOB AND TUBE WIRING

Bennie, does that stand for "Bennie's Stuff"?

Karl, I'm obviously not translating very well. From the movie Cool Hand Luke, "what we have here is a failure to communicate."

In your last post you said,

Roger, where does the NEC prohibit using the hot from one NM and the neutral from the other?

I have not said this was prohibited in any of my post.

We are saying the 1999 change allows this.

and not only do I agree, I absolutly agree.

What's happening is, the words "cable" and "circuit" keep getting crossed over or changed from one post to next.

Roger

 

[don_resqcapt19]

Re: KNOB AND TUBE WIRING

Roger,
If the wiring method is nonmetallic, there are no restrictions on how you install the conductors for the circuit(s) other than the rule in 300.20(B).
Don

 

[roger]

Re: KNOB AND TUBE WIRING

OK, so you guys are saying that there is no concern beyond 300.3 with for example, a two pole 240v circuit feeding a dryer in it's own cable and a single pole 120v circuit feeding a washer in it's own cable, sharing a grounded conductor.

For the above these circuits are on their own breakers, one single pole 30A breaker and one double pole 30A breaker, we aren't talking about a super neutral in this situation.

Now let's forget 300.3 and for starters look at 110.10, do we comply here? Now if the grounded conductor actually gets shared between the two conductors on say leg #2, aren't we going to possibily overload the conductor? If the circuits are specific to utilization equipment (forget the dryer and washer and say maybe one is already at 50% of a branch circuit say a room A/C ) there could be more violations.

This is my point, a circuit is specific. I agree more than one cable can be a circuit and vice versa, but we can not share conductors of circuits to serve each others needs. If we were to indiscriminatly make these kinds of connections it is also possible to violate 240.8

These examples aren't all inclusive.

Roger

[ July 15, 2003, 02:11 PM: Message edited by: roger ]

 

[don_resqcapt19]

Re: KNOB AND TUBE WIRING

Roger,
In my opinion, the current code would permit someone to install two circuits using two MN cables with the hot for circuit 1 and the neutral for circuit 2 in cable A and the neutral for circuit 1 and the hot for circuit 2 in cable B. This is not a good practice, but it is permitted by 300.3(B) starting with the '99 code.

 

[roger]

Re: KNOB AND TUBE WIRING

Don,

Roger,
In my opinion, the current code would permit someone to install two circuits using two MN cables with the hot for circuit 1 and the neutral for circuit 2 in cable A and the neutral for circuit 1 and the hot for circuit 2 in cable B. This is not a good practice, but it is permitted by 300.3(B) starting with the '99 code.

once again we are in agreement.

Now, let's say we have two three phase booster heaters. These heaters have two large elements that the circuit is sized for, and one small element in them. There is a three conductor cable and a two conductor cable available. We feed booster heater #1 with the three conductor cable. (Phases A,B,C, C is the small element) Now We feed booster heater #2 with the two conductor cable, (Phases A&B) we still have the small element not served in this Booster heater so we grab C phase from the three conductor cable. Now the three conductor C phase is serving two loads and on a seperated breaker from booster heater #2's two pole breaker. If some one opens booster heater # 1's breaker and removes it, and is holding C phase in their hand and booster heater #2's thermostat closes, wouldn't they have a good chance of getting hammered? :roll: So,let me ask, would you say this installation is legal?

Roger

[ July 15, 2003, 04:38 PM: Message edited by: roger ]

 

[websparky]

Re: KNOB AND TUBE WIRING

Karl,
Here are the two codes you mention. I added the bold to 2002 code to show the added text from the 1996 code.

NEC 2002 300.3(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (4).


NEC 1996 300.3(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors shall be contained within the same raceway, cable tray, trench, cable, or cord.

I guess I'm still confused as to how the 1996 code permits your point.

Thanks,
Dave

 

[websparky]

Re: KNOB AND TUBE WIRING

Karl,

Maybe I wasn't paying attention! Sorry!

This is what you were referring to;

In 300.3(B)(3)

(3) Nonferrous Wiring Methods. Conductors in wiring methods with a nonmetallic or other nonmagnetic sheath, where run in different raceways, auxiliary gutters, cable trays, trenches, cables, or cords, shall comply with the provisions of 300.20(B). Conductors in single-conductor Type MI cable with a nonmagnetic sheath shall comply with the provisions of 332.31. Conductors of single-conductor?type MC cable with a nonmagnetic sheath shall comply with the provisions of 330.31, 330.116, and 300.20(B).

This was added in the 1999 code and because it was, you are saying it is giving us permission to wire circuits improperly?

Am I on the right track?

Dave

 

[don_resqcapt19]

Re: KNOB AND TUBE WIRING

Roger,
Your installation may or may not be a code violation. It would depend upon the details of the installation, but there is nothing there that would be a violation of 300.3(B) which is the topic of this thread.
Don

 

[roger]

Re: KNOB AND TUBE WIRING

Don,

Roger,
there is nothing there that would be a violation of 300.3(B) which is the topic of this thread.
Don

The actual topic was whether K&T is legal.


In your post of 2:59 you are describing individual circuits from more than one cable not overlapping circuit conductors.

Now, I still ask for someone to explain how 300.3(B)(3) modifies other code sections or allows overlapping circuits. I have not seen anybody sell me on this being permitted yet. Sharing conductors from more than one cable is a given.

This is my last post here. (I hope )

Roger

 

[karl riley]

Re: KNOB AND TUBE WIRING

Don, you say it as clearly as it can be said.

Roger, I would love to hear that this way of running conductors is not permitted. But it does seem to be at present.

Bennie, I will certainly give you a call in Portland.

Karl

 

[karl riley]

Re: KNOB AND TUBE WIRING

Oops! I replied without reading page 3 of this thread.

Dave, yes, that is what I was saying. I would like to go back to the 1996 Code which would not allow the kind of wiring I was describing.

Roger, I realize there would be ways of using conductors from two cables which would violate other sections of the Code. I don't know that the example I gave involves any violations.

And how did this all relate to K&T? I was saying that under present Code one could wire a light circuit in the old K&T way (without the porcelain insulators) by using two separate NM cables, one for the hot and the other for the neutral. This would produce the high magnetic fields that K&T does.

Maybe this thread has run its course! Communication can be hard through typed words. But a lot gets cleared up anyway.
Karl