Ok, here goes.... I know that 30-104(a) states that "Luminaires, lampholders and lighting track shall not be connected to a branch circuit protected by overcurrent devices set at more than 15A IN dwelling units". Yet 30-104(c) states "20A in other than dwelling units where the input voltage does not exceed 347V nominal".. So for example if I have a garage thats attached to my "dwelling unit" the lights can't be protected by more than a 15A overcurrent device, yet if I have a detached garage, garden shed, gazebo or even a dog house with some form of luminaire within it I am allowed to use a 20A overcurrent device??
I am just curious as I asked one inspector a while back and he said it would pass according to what the code states, but we both asked another inspector and he said it would not pass because such buildings are on the same property as the dwelling..
Dwelling unit is defined as having certain facilities. Although the bathroom isn't in the definition, it isn't reasonable to say the bathroom is excluded. The same would apply to an attached garage.
Using a farm as an example, the dwelling unit is on the property, but the shop might be a truck ride away and clearly isn't a dwelling unit. To require a legal subdivision to get around all dwelling unit rules in the shop isn't a reasonable application of the definition.
Inspector 2 would need to make up another rule to make his application of the definition reasonable in more circumstances. Since he can't do that, he must be wrong.
I suppose by strict interpretation the detached garage is not a dwelling unit but is very likely fed from a dwelling unit. so by extension if the circuits are fed from a dwelling unit and the circuits must comply with those rules regardless of the sub panel. OK that is 1 side of my thought process. What about the garage requires a 20 amp lighting branch circuit? What about a barn fed from a dwelling unit? Where are each of the outbuildings fed from? What activities are going on? A commercial garage on a residential/ commercial property. I think it is likely that unless the garage has a special need for a 20 amp lighting branch and it is on a residential property fed from a dwelling unit I might not approve the use of 20 amp branch circuits. If the building was actually large enough to need 20 amp lighting circuits I would consider it but those buildings are almost non existent in this city so it might be moot here.
The other thing I am curious about is the rational for limiting the branch circuit capacity. In commercial applications there are lots of problems with the large number of luminaires that can be connected to a 347 volt lighting branch. The problem is revealed every time the electrician wants to turn off the power to change a ballast he must turn 20 to 30 fixtures off which usually leaves too many people in the dark including the sparky changing the ballast.
I agree that a detached garage is not a dwelling unit but some electrical code rules and building code rules do make a garage on a residential lot part of the wiring requirements for dwelling units like 26-714 requires an outlet and branch circuit for a garage that is part of a single dwelling unit. Attached or detached it is still considered as part of a dwelling unit. By extension then, a detached garage could be considered as part of a dwelling unit.
Ahh see this is where it gets a bit messy I guess. The question originted not so much by the need for a 20 A lighting circuit ( garage was an example) but the fact that a small garden shed exists with a 20A circuit supplied to it to feed a couple of 20A T-slot GFI's. It is now requested that a light be installed in the shed and according to code its not "In the dwelling" so I was thinking legally I can supply the fixture from this circuit without having to change the breaker in the panel to a 15A rated device as well as the GFI's. Also I am curious, would rule 30-104(a) not apply to portable lighting such as a table lamp or a trouble light? Just seems that if I plug in a trouble light to a normal 15 A receptacle its code compliant yet if I plug it into my T-slot 20A receptacles in my kitchen its a violation is it not?
I would put a 4 cct sub panel in the garage, then the plugs can stay 20 amp. It just isn't worth the argument. Having said that, it would be code compliant to add the light to the existing circuit. In fact, the light probably presents less of a hazard than the receptacles. To be really safe, you could protect the light with the load side of the GFI.
Here is my usual rant: Electricians need to be able to take the rules at their normal meaning.
Where I am, we once had to track where inspectors worked, because they "interpreted" the rules differently. I even had to explain to one customer that her wiring had to be different than her friend's, because the inspectors were different.
Because the inspectors "interpreted" the rules differently, if one was away, no other inspector wanted to answer questions about work being done in that inspector's area, and there tended to be a lot of questions.
Even when inspectors agree on a nifty application of a rule, it puts everyone in a position where they need to phone an inspector when something new comes up. By the way, some inspectors don't like the number of questions they get, either. He didn't actually say that, though. What he actually said was "go ahead and ask your question, everyone else does."
When the rules suck, CSA should re-word them. That's their job. If my work were as sloppy as some of the rules, the inspectors would reject it, just as they should reject sloppy rules. I'm absolutely against sloppy applications of sloppy rules.
It's pretty cool to be able to phone an inspector with a question. It isn't cool to ask the definition of a dwelling unit, when it's clearly defined in the front of the book.
If it complies with a strict interpretation (or any other kind of interpretation) of the code, and it isn't an unreasonable hazard, it must be must be what CSA intended, or they would amend the definition.