Can I Run Romex Wire Between Joists In Photo?

[The Computer Audiophile]

Hi Guys - Does anyone know if it's safe to run Romex electrical wire through the joists pictured below? The insulation seen in the photo is from 1941. The wire would run on top of the insulation.

 

This is so I can put in another electrical outlet that runs to my dedicated sub panel for my audio system.

 

[esldude]

https://www.sterling-kansas.com/DocumentCenter/View/146

 

Here in a simple PDF is a copy of the 2011 NEC (National Electrical Code).  You can download it, do a control F for joists and it will take you to the pertinent part.  Which will be page 70-136 (pg 139 of the 879 page PDF).  You'll see if you read on in other sections they more or less prefer you run wire in bored holes in joists and studs.  This protects the wire from incursion from nails. In other instances they require some protection though there are various other conditions.  Boring a joist for Chris' purpose is just fine and dandy.  Their only requirement is the hole be minimum of 1.25 inches from the edges of the joist.  Which btw is mainly to prevent nails or screws contacting the wire. The other ideas in my other links about hole size and position are being extra careful and good ideas, but not even part of the code.  

 

There are the 2014 and 2017 versions of the updated NEC, but they aren't different from this one in regard to boring holes in joists.  This version was easy to download and access.  

 

So you've got your answer.  How do you think houses are wired anyway?  They have to bore holes in studs, headers, and joists.  They don't want you notching edges without other precautions.   With exposed crawl spaces or attics you can staple over such framing features if they are not accessible to other use on a regular basis.  But in a case where Chris needs a hole to get to the wire destination drill your hole and move on.  There is nothing to worry about. 

[Speedskater]

31 minutes ago, davide256 said:

Sounds like a code violation to me....

What's the code violation?

15 Amp circuits require 14AWG or larger.

20 Amp circuits require 12AWG or larger.

Some situations, like long runs, high ambient temperature or high conduit fill may require oversize wires.

 

Note that most receptacles are limited to 10AWG or smaller.

 

While one step oversize is always good, larger than that is quickly diminishing returns.

 

[esldude]

42 minutes ago, One and a half said:

With the new rules, the actual testing procedure is more streamlined. Once the fixed wiring is installed and all compliance with that occurs, the next stage is electrical testing.

Results are recorded.

 

So the IR or Insulation Resistance test is performed as a normal part of testing, like for polarity and earth fault. 

Yes, but that is Aussie and New Zealand code.  It would be all upside down for where Chris is in the USA.

 

Just kidding guys. 

 

What Chris is wanting to do is pretty basic.  I don't see any death defying aspects to it. 

[wgscott]

Those protruding wood screws are what scare me the most about Romex.

 

I'm not an electrician, so my opinion doesn't count, but I'd at least ask someone knowledgeable if armored BX, or wire inside a metal conduit, would be safer.

 

Also, make sure DIY wiring doesn't void your homeowner's insurance policy.

[Account Closed]

I would get your electrician friend involved and check the local code. As mentioned above, insurance is the big concern.

[Ralf11]

yes, the city or state code will tell you - you can usually look it up in city ordinances

 

most places have simply adopted the NEC, US Nat'l Electrical Code but always possible they altered it when adopting

 

did you get a permit for this work?  the inspector will let you know

 

also, you may wish to exceed code - I have used conduit in my house even when not required...

[sandyk]

7 hours ago, The Computer Audiophile said:

Hi Guys - Does anyone know if it's safe to run Romex electrical wire through the joists pictured below? The insulation seen in the photo is from 1941. The wire would run on top of the insulation.

 

This is so I can put in another electrical outlet that runs to my dedicated sub panel for my audio system.

 

 

https://www.thespruce.com/what-does-romex-or-nm-mean-1821530

 

" ….. For homeowners and professional electricians running new circuits or extending old circuits inside walls and ceilings, NM cable is the material normally used."

 

Chris

 Personally, I don't see a problem given the use of high quality connectors and good workmanship, as the USA regulations governing this type of thing are very different to most 230VAC 50HZ countries. I would expect that you already have a decent DMM and know how to use it. You could also install an Earth Leakage Breaker for added safety. 

Neither should you need to use metal conduit, as you could also run vulnerable areas in plastic conduit for added protection from rodents, possums etc. if you were at all concerned.

 

 Regards

Alex

 

P.S.

Quote

Also, make sure DIY wiring doesn't void your homeowner's insurance policy.  - wgs

 

[One and a half]

Drilling holes through supports which hold a building together is not a great idea. If old timber is any guide as in my place, the longer it's in use, the hardwood ends up like hardened steel, of which swords can be spawned, it's THAT hard, drilling large holes can be a lengthy exercise. 

Generally, cable can be thrown on a surface and left provided there's little chance of someone standing on it, or it being disturbed. Local rules apply however.

[sandyk]

16 minutes ago, One and a half said:

Drilling holes through supports which hold a building together is not a great idea. If old timber is any guide as in my place, the longer it's in use, the hardwood ends up like hardened steel, of which swords can be spawned, it's THAT hard, drilling large holes can be a lengthy exercise. 

 

 Not much fun either when you are in a confined ceiling space !

I would also turn off the main circuit breaker while working there, and test the  new wiring thoroughly with a decent  DMM before switching it back on.

[One and a half]

1 minute ago, sandyk said:

 

 Not much fun either when you are in a confined ceiling space !

I would also turn off the main circuit breaker while working there, and test the  new wiring thoroughly with a decent  DMM before switching it back on.

Any modification to fixed wiring needs to be tested with an IR tester 2 x working voltage to be clear about methods. For 230V systems, 500V, 400V, 1000V. Now there's some debate as to how long the IR tester needs to test, for high voltage 1 minute is common, since a short test of 5s is enough to pass, but longer times insulation can break down and becomes apparent, especially if there's moisture or some tracking due to carbonising.

For AC cables I make for home, and for safety in mind, the IR tester is used to check the polarity of the connections and how good the insulation is. The cable is tagged with a date, credentials, there's an AS for that for commercial/industrial use, but not necessary for domestic.

[One and a half]

20 minutes ago, sandyk said:

 

 Not much fun either when you are in a confined ceiling space !

I would also turn off the main circuit breaker while working there, and test the  new wiring thoroughly with a decent  DMM before switching it back on.

Switching off the main supply is a great idea, isolating the upstream is even better since unmetered mains cables can be anywhere. I don't climb in the roof any more, not agile enough.

[sandyk]

6 minutes ago, One and a half said:

Any modification to fixed wiring needs to be tested with an IR tester 2 x working voltage to be clear about methods. For 230V systems, 500V, 400V, 1000V. Now there's some debate as to how long the IR tester needs to test, for high voltage 1 minute is common, since a short test of 5s is enough to pass, but longer times insulation can break down and becomes apparent, especially if there's moisture or some tracking due to carbonising.

 Garry

 Agreed that this is desirable, but Chris would be using brand new high quality mains cable, and his experience in other areas would undoubtedly help in the workmanship area too.

 

Alex

[wgscott]

If the structure dates back to 1941, the potential (pun intended, as always) for an unpleasant surprise in wiring is non-negligible.

 

[One and a half]

1 minute ago, sandyk said:

 Garry

 Agreed that this is desirable, but Chris would be using brand new high quality mains cable, and his experience in other areas would undoubtedly help in the workmanship area too.

 

Alex

Doesn’t matter , old or a new install, an IR test is necessary, just passing the info about AS rules, which btw will change with new ones introduced this year and effective Jan 1 2019.

[sandyk]

34 minutes ago, One and a half said:

Doesn’t matter , old or a new install, an IR test is necessary, just passing the info about AS rules, which btw will change with new ones introduced this year and effective Jan 1 2019.

 Garry

 We are talking here about the USA where they seem to be able to many things electrically that are a big NO, NO, Downunder.

Even the Kiwis are able to do some electrical stuff themselves.

 

Alex

[sandyk]

40 minutes ago, wgscott said:

If the structure dates back to 1941, the potential (pun intended, as always) for an unpleasant surprise in wiring is non-negligible.

 

 Bill

 There is always the possibility that the Ceiling  Insulation is laid on top of some old electrical wiring, which is part of why I suggested turning all power off while working there.

 

Alex

[esldude]

https://www.familyhandyman.com/floor/how-to-drill-through-floor-joists/view-all/

 

 

[esldude]

In my above post the article linked is more permissive.  The video is following IET standards. 

 

Keep holes minimum of 2 inches from the top and bottom of the joist.  Keep the hole diameter at or less than 25% of the joist height.  Put the hole as close to the middle as you can vertically.  Don't put it near a load bearing wall under the joist.  It is best to avoid the center third of the joist span for such holes.  

 

 Romex really wouldn't need any protection other than as someone mentioned rodents.  You could use thin wall emt or plastic conduit if you wished.  You are NOT supposed to run Romex thru conduit.  You should use THHN wire if you go with conduit. 

 

Calculations I've seen show even a hole 33% of joist height directly in the middle of a joist only reduces strength by 4%.  

[moko]

my Elecrtican (certified 40yrs and still working) said its fine to lay it on top of the insulation....even that old houses....its rated for that.

 

and I'm at carpenter for 30 yrs....the plumbers and electricians having been drilling holes in joist ,just like said above....location and hole size must be correct

[Superdad]

What wire gauge is your Romex?  If it is for your audio system I’d try to stick with #10.

[The Computer Audiophile]

5 minutes ago, Superdad said:

What wire gauge is your Romex?  If it is for your audio system I’d try to stick with #10.

Using 12 AWG from the sub panel to the outlets.

[Speedskater]

I have a1939 home in the USA.  There are several Romex® runs just like pictured.  It's done all the time. But there are a few locations that don't permit it.  It won't be in the old insulation, so that won't be a concern. 

[Account Closed]

Chris, You may want to consider a shielded Romex. I found this just as an example. I agree with the 10 Gauge as well.

 

http://www.lessemf.com/wiring.html

[4est]

22 hours ago, esldude said:

In my above post the article linked is more permissive.  The video is following IET standards. 

 

Keep holes minimum of 2 inches from the top and bottom of the joist.  Keep the hole diameter at or less than 25% of the joist height.  Put the hole as close to the middle as you can vertically.  Don't put it near a load bearing wall under the joist.  It is best to avoid the center third of the joist span for such holes.  

 

 Romex really wouldn't need any protection other than as someone mentioned rodents.  You could use thin wall emt or plastic conduit if you wished.  You are NOT supposed to run Romex thru conduit.  You should use THHN wire if you go with conduit. 

 

Calculations I've seen show even a hole 33% of joist height directly in the middle of a joist only reduces strength by 4%.  

The rodents should not be under estimated. Modern wire insulation is often "tasty" to them. I'd use metal clad(MC) cable. In my shop, I had a mouse eat the insulation on a machine that was 30'/10M from any exterior wall and 5' off of the ground. I also recall a client complaining because his daughter's pet rabbit ate through live wires in a crawl space while AWOL for a couple of days. I seem to recall mention of the plastic having some soy in it.

[Speedskater]

16 hours ago, bobflood said:

Chris, You may want to consider a shielded Romex. I found this just as an example. I agree with the 10 Gauge as well.

http://www.lessemf.com/wiring.html

Shielded NM (Non Metallic cable) is not needed.  Stick with real SouthWire brand Romex®.

Stay away from those weird people at the above link.