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kama 11-13-2008 01:32 PM

code details for boxes
Hello to all. We are renovating our basement which is our first big project to the home we are in now.

We have almost completed the framing in the basement which we have done with steel studs. We are now working on the rough in of the electrical and our last short wall before our insulator contractor comes in to spay in the foam.

We are looking for some help with the Canadian electrical code as we are having issues with the inspector and what he would like us to comply to.
They are not being very descriptive of what they want, which I think is done more to make you think that you are incapable of doing the work yourself, so when you ask them a question they have tended to evade any sort on concrete answer.

Basically we are trying to not only meet code, but also to exceed it in that the work will meet new code requirements down the road not leaving us with some expensive fix should we need to make changes down the road. IE running more breakers than actually needed as we have the pannel space to do so.

One issue is partly due to the foam insulation. As they are exterior walls they want us to use vapor barrier cups, even though the spray foam acts as its own vapor barrier. Foam is not commonly seen in homes here yet, but is just starting to become something people are considering using due to our climate. Because of this inspectors here know very little about how this fits in with the code of the day which deals with either rigid board, or batt insulation both of which still require the vapor cups on exterior walls.

Here is the issue. Steel studs require us to use specific metal boxes which have a long ear at the back that must hit the wall for stability. They don't fit into the cups worth a darn unless you place a small slit in the back to accomodate this, which in the means of a vapor barrier defeats the purpose completely.

How do we keep them happy in this scenario.

Next issue is the wires are all run on stand offs to act as the bracing that the staple would provide on the wood stud. (which can't be done on the steel) Code in Canada states that the wire can not be run parallel or on the steel stud. They must be either run on a small piece of wood attached to the stud, or run with stand offs. We chose the stand offs as it is much easier and economical.

Our question is what distance of wire should be left between the stand off point at 8" from the box and the box itself. Should it be 10" before it runs into the box, or 12"? We can't seem to get any specific answer. All they tell us it that it must have a gentle curve with some excess wire.

What purpose does this extra wire serve? We have noticed that in the US or at least in books published in the US they don't have to leave this at all.

We are just looking to do things right the first time round.

Thanks in advance for any answers you can give us.

220/221 11-13-2008 07:18 PM crazy Canucks :laughing:

I live in the desert and don't have anything of value to add.:jester:

We use regular boxes on steel studs, I don't understand what a vapor cup is and I have no idea why it would be a requirement to leave extra wire at a jbox.

Hope that helped :thumbup:

kama 11-13-2008 09:20 PM

code details for boxes
I have to laugh at your reply. Oh so true. That is exactly what we are thinking too! However you have to make the wheels turn the right direction or there is trouble to be paid down the road....So you just nod for the most part and go OK.

Codes for the most part have a use, but some of this stuff well is just plain crazy.

All we could think of is possibly extra wire is needed for earthquake issues?

Anyway thanks for your reply. It is much appreciated.


Termite 11-13-2008 11:24 PM

My assumption about their requirement for a little slack in the wire is to provide a little extra for future needs...Changing devices or whatever. Perhaps there's some seismic justification as well.

I'm with 220/221 on the vapor barrier cups. We see icynene-type sprayed foam on a fairly regular basis...And I'm no expert on the stuff...But I've never seen what you're talking about. Sorry, I wish I could be more help on that!

All model codes (CEC, NEC, ICC, etc) are written for a reason, and usually a very good reason. Often the codes seem unattainable, strange, or silly until you gain an understanding of the justification for the requirement. Where things sometimes get plain ridiculous is when individual jurisdictions tweak the code to suit their own opinions.

rgsgww 11-14-2008 10:52 PM


Originally Posted by thekctermite (Post 184671)
Where things sometimes get plain ridiculous is when individual jurisdictions tweak the code to suit their own opinions.

Just like chicago land...isn't oklahoma's code kind of odd...

rfrennette 01-29-2009 05:26 PM

I am doing the same thing in Canada

I too am finishing off my basement in London, Ontario, Canada. I used steel studs and am now installing the electrical boxes with the vapor barrier surround. How did you install the VB surrounds without cutting them and did you get the inspector to pass it?



rfrennette 01-30-2009 10:25 AM

Spoke to the Electrical Inspector in Canada
Vapor barriers around electrical boxes have nothing to do with the electrical inspector, it is a building code inspector who would be concerned. You can make the slits for the electrical boxes then seal them up with acoustical sealent. You could use plastic boxes on the steel studs then no vapor barrier is needed, just seal the wires entering box. Rule 12-510: Cable strapped 300mm or 11.8in of the outlet box and every 1.5m or 59in throughout the run. Rule 12-516: Cable has to be 32mm or 1.25in from face of stud to protect from nails, drywall screws. Use 16MSG steel plate if less over cable.You don't need wood on the steel studs to run wire parallel, us tie wire or cable straps. Cable straps have a spot for 2 nails but just fold it around cable and put 1 screw through both holes into stud to secure at 300mm from box etc.

Hope this helps

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