I've heard of several contractors that run 12/3 from the panel to the farthest room from the panel and split the circuit,red for one circuit and black for another.I understand that you wouldn't want these on the same phase but where my problem begins is now they have added a room addition on to the house and a DIY just attached to an existing circuit and now is overloaded.Actually it's not my problem but now the homeowners are upset about paying this DIY for all these problems,and he won't return there calls......imagine that!
No,the overloaded circuit was on the 12-3 wire and I'm sure the other side of the 12/3 is at it's max as well.The circuit in reference has 22 plugs,Broan hvl(1600 w),6 recess cans(75w per),whirlpool tub and an outside plug and the owner called me to replace a bad breaker and after investigating other than at the panel I found the loaded up circuit.Are there others that do this and what are all the pros and cons?
The cons are heavily loaded circuits have more voltage drop and inadequate room for expansion.
No, what are you asking? There is nothing wrong with running a double-pole circuit from a breaker with the handles tied. It is two 20 A circuits with a shared neutral, and in my opinion, has slightly less voltage drop for normal loads than when not having a shared neutral.
The problem is that two circuit is obviously not enough.
You just describe at least a 50-70 amp load. There are two circuits where five are needed. Run some more cable. Two more runs of 12-3G would be a good start. If the distance is over 50' (wire length), use #10 for the heavier loads.
I have over 17 years in residential and have seen this a time or two mainly in older kit circuits but as a young apprentice was exlained that it wasn't kosher.So as I was trained I moved on to doing things the way I was taught.I'm starting a 3700 Sq ft house and I'm going to have 4 circuits on the far side of the house,so would I just run 2 12-3 runs from the panel to the far side of the house. I know not to put the same wires on the same phase and to put on a 2 pole breaker.What my concerns are what kind of problems might I encounter by doing this as long as I don't overload the circuit.
If you are going to run 3 wire to a receptacle box and split it there you have to connect all neutrals together and go to the receptacle with a tail. You must not use your receptacle to connect the neutrals. Everything else you seem to know.
What Bill is saying is that if you use the first receptacle box to split into two circuits, then you must pigtail that receptacle so that the neutral for the other circuit is connected back to the panel by a wire nut (rather than daisy-chained using the screws on the receptacle itself).
And if you run three wire to every receptacle box, then this applies at every such receptacle to make it less likely that the receptacles could be energized at 240 V.
I use a multiwire circuit (12/3) to the kitchen. One side feeds the countertop outlets on one side of the kitchen, the other feeds the dishwasher disposal (on the same side of the kitchen). Also, I've run a 14/3 to supply two forced air gas furnaces next to each other.
By the by, the only time the code requires a handle tie or common trip breaker is when the two circuits are on the same yoke (like a split outlet). Some inspectors have insisted that I put in a handle tie because the two circuits are in the same box. It is a little safer for some goof who starts poking around in the j-box, and checks only one side of the multiwire...