This thread may go the way of the "is a switch an outlet?" thread if we're not careful!
If a 15-amp circuit ls limited to supplying no more than 600 sq.ft., is the quantity of rooms, or more specifically, the linear wall space, relevant? Does it matter whether we're talking about one large room, say 20' x 30', or several rooms, say 4 rooms at 10' x 15' each?
Ignoring window and door openings (or assuming ideal positioning of these), one 20' x 30' room would have a total wall length of (2*20 + 2*30) 100 feet, requiring a minimum of (100/12 = 8.33) nine receptacles. One 15a circuit covers this easily, right?
The same area divided into four equally-sized rooms would have a total wall length of ((2*10 + 2*15)*4) 200 feet, requiring a minimum of (200/12 = 16.67) 17 receptacles. One circuit? Would this be code-compliant? Depends on who you ask, apparently.
I have not seen anyone claim that, to be compliant, you must have
both no more than 600 sq.ft. per 15a circuit
and no more than 13 receptacles. What if I wanted a receptacle every 2 feet? A 10'x15' room would require 2 circuits.
That would exceed the 600 sq.ft.-per-circuit requirement. Four such rooms would require a total of 8 circuits. But wait! I thought we could supply 600 sq.ft. with one 15a circuit. Well, is it area or quantity? It can't be both.
Apparently, it's not just a 13-receptacle-per-circuit limit, nor an area-based limit. It must depend on somethimng else, something much less arbitrary. How about basing it on expected use? What about lighting?
Does it matter if a circuit supplies both ceiling and receptacle outlets, or only receptacle outlets? What happens then? Do we use the outlet-quantity limit or the area-served limit? Is there a limit on ceiling outlets per circuit?
Or should we calculate each circuit's load using expected loading? I can see placing two or three bedrooms' receptacles on one circuit if the lighting is separate, or perhaps one entire room on one cicruit, but how big is a room?
There are general-purpose cicruits, and then there are specific loads that are ubiquitous, and may or may not be too much for a GP circuit. Bathrooms require 20a receptacle circuits, yet hair dryers are often used in bedrooms.
50 to 75 years ago, one or two circuits was enough for most of a house, since lighting was the major load, appliance circuits aside. Now, lighting is a fraction of an entire residence's load. What has changed over the yeras?
It seems that the quantityof receptacles per circuit is about the same; just the area served by each circuit has reduced. Why? We have increased our electrical usage by surrounding ourselves with appliances and electronics.
Who knows what the future holds? We could argue that efficiency of electrical use will increase, and we shouldn't have to supply electricity as "densely" as we do now. We just have to go by what we have now, even though most people don't use half of their service's capacity, just in case.
Okay, my fingers and brain are competing for blood supply, so I'm taking a break. Later!
