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Wiring Overload? Keep K&T wire or run new NM off junction box?

Wiring Overload? Keep K&T wire or run new NM off junction box?

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  #1  
Old 06-10-11, 11:58 AM
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Wiring Overload? Keep K&T wire or run new NM off junction box?

Is it better to keep 4 K&T wires that runs to a bulb fuse or to run 4 new NM wires off of 1 BX wire from the bulb fuse to a junction box?

This is what is going on:

I currently have a bulb fuse panel with old K&T. Each fuse on the old panel has about 4 set of K&T wiring running to it.

An electrician used BX wire to connect a junction with a bulb fuse. From that junction box, he split added 2 new outlets in the house over NM wire.

My question is, would it be better to route the other exiting outlets on K&T into the junction box ? With this I will have a ground and be on new wiring. However, I would adding quite a few more wires to the junction box.

I am stuck if will this overload the BX and NM wires? The electrical told me that keeping the multi K&T to fuse is better than running a bunch of NM off of the 1 BX wire. But my logic is that no matter how many devices or outlets you have, once it goes to 15AMP, the fuse would blow anyways. Therefore, there can't be more current on the wire than what it can handle.

All BX and NM wires are 12 gauge wires (able to handle 20AMPs)
My old panel is a 30AMP main, 2 15AMP with 1 20AMP fuse.


Thanks
 
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  #2  
Old 06-10-11, 12:44 PM
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Originally Posted by vdozer View Post
would it be better to route the other exiting outlets on K&T into the junction box ?
No it is best to replace K&T completely, but if you cannot do that then it is best to leave it as-is. There's really nothing you can do with it legally other than leave it alone.

Your thought regarding the 15A fuse blowing based on total load regardless of how many wires are connected is essentially correct as long as all of the wiring is at least 14 AWG. The issue though is that very old wires have very fragile insulation and connections. When you mess with them the insulation breaks off and the connections loosen up leaving a more dangerous situation than when you started.

With this I will have a ground and be on new wiring.
The K&T is still ungrounded. The BX should be considered ungrounded unless it is reasonably modern.

However, I would adding quite a few more wires to the junction box.
In the first place, I would not recommend adding any thing to a 4 circuit 30A service. Second I doubt that any new circuit installed to this panel would be legal as there is no AFCI protection and sketchy, if any, grounding. You should really consider having a service replacement done.
 
  #3  
Old 06-10-11, 01:06 PM
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thanks, what i actually meant by "would it be better to route the other exiting outlets on K&T into the junction box ?"

is not to reuse the K&T wiring but run new NM wires to the junction box connected to the panel by the BX wire. The BX is new and is grounded to the panel.

i am just wondering what is safer? using outlets connected by K&T wire to the fuse or outlets connected off of the heavily junctioned BX wire that connects to the fuse

it sounds like running off the BX is still safer.

i agree, complete overhaul is being looked at as well. thanks!
 
  #4  
Old 06-10-11, 01:24 PM
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I don't think it really matters a whole lot; I can't think of a reason one would be safer than the other. I would probably run the new NM cable directly to the panel and leave some extra cable looped nearby so that when you replace the panel you can run the new cables directly to their own breakers.
 
  #5  
Old 06-10-11, 01:35 PM
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ah interesting. i thought with the old K&T that they might have a higher chance of fire given they are old. essentially running NM wire would reduce that risk. as a side benefit I would have a ground wire too.

ok, besides the ground wire. would i reduce the chance of electrical fire by running new NM? if not, there really is no value add and i might just add a ground wire for peace of mind. thanks!
 
  #6  
Old 06-10-11, 01:44 PM
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Maybe I'm not quite understanding your question. Are you thinking about adding new wiring to places in the house where there currently is none? Or are you thinking about replacing old K&T wiring with new wiring?

Basically my point is that there is little difference in safety between modern NM cable and modern BX cable. Either one of those options is much better than K&T.
 
  #7  
Old 06-10-11, 01:56 PM
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sorry this is one hard topic to explain.

YES! basically replacing the K&T wire. i am evaluating which is better, leaving the K&T for an outlet OR run a new wire to that oulet with NM wire and not use the old K&T wire. The only problem I have been told is that I might overwire that junction box with that 1 BX feeding multiple outgoing NM. see the ilustration below, moving the load to NM wires instead of using K&T. see before i have 4 K&T going to the fuse and 3 to NM, after it will be 0 K&T but 7 to NM off of the 1 BX wire


BEFORE:
-------4 K&T----- [FUSE 15AMP].....BX(AWG14)...... {Junction box}______3 NM___(AWG14)

AFTER

-------0 K&T----- [FUSE 15AMP].....BX(AWG14)...... {Junction box}______7 NM___(AWG14)

(Not replacing K&T as that would just be a wire in between the walls. I am running the NM under the house in the crawl space)

Btw for wires, some wires have only a gauge rating like 12 gauge but some have AWG 14. I assume they are not the same? The NM have AWG14 and then I found some at Lowes with just a 12 gauge rating but no AWG.
 
  #8  
Old 06-10-11, 02:16 PM
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AWG stands for American Wire Gauge. 14 gauge would be used on 15 amp circuits and 12 gauge would be used on 20 amp circuits.

I am not expert on electrical, but I would not consider any K&T to be safe. I don't know for sure, but I think the thickness of the wire used for K&T is less than 14 gauge. That would make it dangerous to use on a 15 amp circuit. Don't add anything else to your house using the K&T. When it comes to that BX wire, you should be concerned with overloading the junction box. Each junction box has a maximum number of wires that can be inside of it. It all depends on the size. That BX wire will be fine.
 
  #9  
Old 06-10-11, 02:18 PM
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Oh okay, would it be possible to just ignore the BX box and run your new NMs directly to the fuse panel box? That would be the best option if you can do it. Seven cables in one junction box is a few too many.

Once the old K&T is disconnected from the power source you can safely abandon it inside the walls. It doesn't need to be actually pulled out.

AWG means American Wire Gauge, so sometimes it will just be called "gauge" or even just a # sign.
 
  #10  
Old 06-10-11, 03:23 PM
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by passing the BX is hard because there are physical wood panels blocking access and i think thus why the guy up a BX wire in there. i would have to drill a BIG hole which might be a problem.

is the risk factor with the junction box a physical risk factor? What if i feed anotehr junction box off the junction box, would that be safer? thanks, this helps alot guys!
 
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