# Watch Out For This Problem



## Joe Tedesco (Mar 25, 2007)

http://ecmweb.com/nec/whats_wrong_082404/

Cover was missing or removed at some time either after or during installation. 

PS: See anything where the twins are used? :whistling2:


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## MDShunk (Jan 7, 2007)

Yeah, that's about the worst paint contamination picture I've ever seen. It also looks like they might have both conductors of the same multi-wire branch circuit terminated on the same twin breaker (same leg).


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## macmikeman (Jan 23, 2007)

MDShunk said:


> It also looks like they might have both conductors of the same multi-wire branch circuit terminated on the same twin breaker (same leg).


I used to consider that an automatic no-no until sombody else got hashed for saying so over at you know where every paragraph of the code book is good for about 8 pages of discussion. I would never ever want to do it, but if the load on the both circuits individually does not cause an excess current draw above 80% continuous or a 100 % non continuous of the rated ampacity of the neutral conductor in question there is no code violation until the 2008 comes out and mandates handle ties. At least as far as I know. If I am wrong about it, I will be happy to get corrected, so feel free if I am. Thats one way I learn stuff.


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## Joe Tedesco (Mar 25, 2007)

Read this for more information:

http://www.inspect-ny.com/electric/multiwir.htm


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## macmikeman (Jan 23, 2007)

Good article Joe, I have been quite aware of all the problems associated with improper use of multiwire branch circuits and how to not open up the neutral since I was a first year apprentice. What I pointed out was that there is not an automatic code violation as far as I know, until you ramp up the load on the circuits in the very questionable practice of landing them on the same leg. However there is no code to cite about it unless you take an amp reading of the neutral wire and show that you are above the rating of the overcurrent device and the ampacity of the neutral conductor. I bet Ryan Jackson could come up with something or other though......


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## Joe Tedesco (Mar 25, 2007)

macmikeman said:


> Good article Joe, I have been quite aware of all the problems associated with improper use of multiwire branch circuits and how to not open up the neutral since I was a first year apprentice. What I pointed out was that there is not an automatic code violation as far as I know, until you ramp up the load on the circuits in the very questionable practice of landing them on the same leg. However there is no code to cite about it unless you take an amp reading of the neutral wire and show that you are above the rating of the overcurrent device and the ampacity of the neutral conductor. I bet Ryan Jackson could come up with something or other though......


 

You can't have a *multiwire branch circuit* unless it meets this simple elementary definition!

Branch Circuit, Multiwire. 

A branch circuit that consists of *two or more ungrounded conductors that have a voltage between them*, *and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.*

*NECH:*

For the 2002 edition, this definition was editorially modified by substituting the word voltage for the term potential difference. 

See 210.4, 240.20(B)(1), and 300.13(B) for specific information about multiwire branch circuits.


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## macmikeman (Jan 23, 2007)

Joe Tedesco said:


> You can't have a *multiwire branch circuit* unless it meets this simple elementary definition!
> 
> Branch Circuit, Multiwire.
> 
> ...



LOL, I was going to put that same wording into my first post,(albiet without the fancy colors or additional links) . Joe, while I applaud you and MD pointing out the practice as unsafe, , what I was refering to is the subtle fact that you cannot redily give us a code violation for the practice, unless the conditions are guaranteed present that I pointed out in my first post in this thread.


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## Joe Tedesco (Mar 25, 2007)

*210.11 Branch Circuits Required*

*OK. let's try this for a "balanced load" :thumbup: *

*"210.11 Branch Circuits Required*

Branch circuits for lighting and for appliances, including motor-operated appliances, shall be provided to supply the loads calculated in accordance with 220.10. In addition, branch circuits shall be provided for specific loads not covered by 220.10 where required elsewhere in this Code and for dwelling unit loads as specified in 210.11(C).

(A) Number of Branch Circuits The minimum number of branch circuits shall be determined from the total calculated load and the size or rating of the circuits used. In all installations, the number of circuits shall be sufficient to supply the load served. In no case shall the load on any circuit exceed the maximum specified by 220.18.

*(B) Load Evenly Proportioned Among Branch Circuits* 

Where the load is calculated on the basis of volt-amperes per square meter or per square foot, the wiring system up to and including the branch-circuit panelboard(s) shall be provided to serve not less than the calculated load. 

*This load shall be evenly proportioned among multioutlet branch circuits within the panelboard(s).* 

Branch-circuit overcurrent devices and circuits shall only be required to be installed to serve the connected load."


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## macmikeman (Jan 23, 2007)

Ok ,, I surrender. Now look again real close at your picture of the panel. The hack who did the job did proportion his hack loads evenly. Look at the two sets of twin 20 amp breakers at the top left corner. He did the same thing twice on opposing legs. Now ignoring the lousy and unsafe practice of landing both hots on the same leg each time, he did evenly divide them to two sides. If all 4 hot wires are carrying lets say less than 5 amps max, then you still would not have any violation here yet. :laughing: But anyway Joe, if I was the inspector I would never ever have let that one pass in any event. Keep up the good work:thumbsup:


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## Joe Tedesco (Mar 25, 2007)

*One more time*

Let's look at this again, I found the larger image for us to review. :thumbup: 

The black and red wires from the same cable assembies are connected to the twin breaker in space 1 and 3, and in space 4.

_I need a job, can I work in Hawaii as an electrical inspector? :laughing: _

Here's an old book from 1904, it has some good discussion on the neutral.

http://books.google.com/books/pdf/M...AJ&output=pdf&sig=JVZvshWfNNzW4DdZysnKQgwpnpg


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