The multiwire circuit can be shut down with a double pole switch. The thing that makes this legal is using a double pole breaker in the panel. (exception 2) Then you can feed line to line and line to neutral circuiits from the same circuit.
210,4(C) Line-to-Neutral Loads. Multiwire branch circuits shall supply only line-to-neutral loads.Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device.
You, you can actually split out both of the 120v "hots" to run 2 120v circuits. Maybe put the lights on one and the GFCI receptacle on another. As long as the GFCI string starts after the split it will work OK. You can feed regular receptacles after the GFCI and provide protection if you connect to the "load" side.
As I said way up thread, you will have about 11a to work with if your
240v heat is 2000w. Of course in the summer you would have both circuits at the whole 20a each.. You get a lot of bang for the buck with a multiwire circuit and it even helps your voltage drop problems if the 2 sides are somewhat balanced since the effective load is based on 240v instead of two 120v loads. You don't see the return path voltage drop since the neutral is only carrying the unbalanced load.A multiwire circuit does only count as a single branch circuit so you can skip most of the rules about sub panels. If you want to be on the safe side you could drive a rod and connect it to the ground wire but it is not required. A double pole disconnect switch is still required and a good idea, just so you can work on the wiring without thinking about someone lighting you up from the house. It can just be the regular wall switch type with 2 poles.
hmmm... well appreciate the input. I have done some reading on multiwire, and I guess it wouldwork fine, but from my perspective, I can't see it as being safer than just two circuits. There are some inherent dangers with multiwire, evidently, and never having wired one, I feel more comfortable with the two separate circuits. Guess I could do a subpanel....
Well, mostly becasue I already spent $ on the 12/2 w/g wire. I will waste $45, which isnt a big deal, and about 2-3 hours in labor.
I am stillthnking subpanel, but was thinking just a 30A, using 10/3 w/g. I would think that would be sufficient for my needs, but I guess it will not give me any expandabilityy. Waht wire for 50A? 8awg?
I don't understand the resistance to running a 3-wire,
240V, 50A run to a sub-panel, and dropping a local ground.Why put so much thought and effort into finding a safe, legal way to do it wrong?
it is approximatley 75 feet
You can use much of the 12-AWG for wiring inside the shed, so it's not a total loss. you said somewhere that the run was around 70', so I think that 8AWG wire will get you 40A (well, 46, but I don't think they make
45A breakers) Anyway, a 40-Amp 2-pole breaker gets you a nominal 9600 watts, to divide up into 240V and 120V circuts however you want.
to be GFCI protected. There are code issues when running multiple circuits to an out building like disconnects, so probably the most sensible thing to do is install a thirty or forty amp feeder(10/3G) or (8/3G) and small panel in the shed
will be GFCI-protected at the house-when the wiring exits the house, I simply added an outdoor GFCI outlet, and put the shed load out of this outlet. So all the outlets, and lighting in the shed will run off this circuit. Easy enough...
heater. I am assuming I need to GFCI-protect this line as well, but maybe I don't. I know the heater itself has a breaker in it (dunno if that is GFCI or not?),but do I need to protect the line from the house (buried 12-24" down in the ground)? I would think I need to, but maybe in-wall heaters do not need to be on GFCI circuits, and/or maybe the buried cable does not need to be protected with GFCI? Thanks for the help
Running two branch circuits between buildings is a violation of "225.30 Number of Supplies. Where more than one building or other structure is on the same property and under single management, each additional building or other structure served that is on the load side of the service disconnecting means shall be supplied by one feeder or branch circuit..." This provision of the US NEC is meant to prevent elecctrical accident caused by multiple sources of current to a buiding.
-- Tom Horne
Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you.
-- Tom Horne
Well we aren't no th>>
RBM wrote:
will be GFCI-protected at the house-when the wiring exits the house, I simply added an outdoor GFCI outlet, and put the shed load out of this outlet. So all the outlets, and lighting in the shed will run off this circuit. Easy enough...
heater. I am assuming I need to GFCI-protect this line as well, but maybe I don't. I know the heater itself has a breaker in it (dunno if that is GFCI or not?),but do I need to protect the line from the house (buried 12-24" down in the ground)? I would think I need to, but maybe in-wall heaters do not need to be on GFCI circuits, and/or maybe the buried cable does not need to be protected with GFCI? Thanks for the help
to be GFCI protected. There are code issues when running multiple circuits to an out building like disconnects, so probably the most sensible thing to do is install a thirty or forty amp feeder(10/3G) or (8/3G) and small panel in the shed
Would you mind quoting chapter and verse for the code language you believe requires GFCI protection for 240 volt cord and plug conneccted devices?
-- Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison
I'm afraid it does not apply to you because the voltage to ground on both circuits is 120 volts. You can run a multiwire branch circuit that can carry both loads but that would still mean changing the line to three wire plus ground.
If you were trying to avoid the installation of a grounding electrode system at the garage it is a bad idea even were the code permits it. A multiwire branch circuit is a single branch circuit for the purposes of the code so a building supplied by one of those circuits does not require a grounding electrode system at the building supplied.
-- Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison
What is the total length of the circuit from the service equipment to the garage? With that information I can find the voltage drop for the circuit.
-- Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison
Yes but it is still a code violation and as one of the guys that crawls into the buidings that all of you sane types have run out of I would ask that you cut us a break and follow the code. That includes providing a single disconnecting means that will deenergize the entire structure as required by the code. If you really want to be nice to us then you could mount the disconecting means outside the building.
"225.31 Disconnecting Means. Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.
225.32 Location. The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall be permitted to be utilized."-- Tom Horne
Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you.
The higher voltages cannot be derived from the same circuit without installing a transformer so the code language permits you to avoid that bit of expense and complexity. The code language on which you are relying is meant to allow separate circuits for such purposes as powering a large item of equipment that requires a completely different voltage such as 240 volt delta three phase with one phase grounded to run a large refrigeration unit. You need the 240 / 3 phase power for the refrigeration unit and you need 120 volt power for service receptacles and lighting. Since 240 volt delta is much cheaper to install as corner grounded delta the cost effective way to provide both voltages is to run two circuits. Another example is a guard house for an industrial complex that has 480/277 volt air conditioning and lighting together with 208/120 volt power for receptacles. In short those exceptions are only intended to be applied were a single branch circuit or feeder cannot supply the needed power.
-- Tom Horne
Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you.
Goedjn wrote
OK OK I have decided to run a subpanel. BUT cripes, while the subpanels are cheap, man, 8/3 AWG is PRICY. OK so using substantially cheaper 10/3 AWG gives me a 30A subpanel. I would think this would be sufficient:
2000W heater, plus antoher 1000W for outlets and such, gives me ~15A, assuming full useage? 30A seems like it would be sufficient, and a LOT cheaper. Comments? thx
#6 AWG aluminum wire carrying fifty amperes would have a voltage drop of 2.1 %.
-- Tom Horne
Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you.
You were doing OK tom and we love the firemen but if you boys are counting on a single disconnect you might get it trouble. It could be SIX separate switches. They just have to be grouped.
225.33 Maximum Number of Disconnects. (A) General. The disconnecting means for each supply permitted by 225.30 shall consist of not more than six switches or six circuit breakers mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard. There shall be no more than six disconnects per supply grouped in any one location.
That is not what the code says. In fact the handbook shows a combo NEMA 5-15 and 6-15 device in the example. (a duplex receptacle with a 120 and a 240 outlet)
SO your thinking 30A would be sufficient to serve my needs? I mean, I could add a 3000W device(s) and still be under...
I got a 100A sub-panel, the grounding bus, will NOT bond the neutral, and will eventually add a gounding rod outside. But do I really need a disconnect?
Get a 2/4 disconnect and install one 15a 2 pole for the heat and two
20a single pole for the 120v loads. Put a GFCI receptacle for the first receptacle on each circuit. You can put the lights on the non-GFCI side. "Diversity" will keep you out of trouble. Be sure to get the suplimental grounding bus, don't install the bonding screw, drive a rod (goes to the grounding bus).210.4(C) ex2 The article I cited when I said the OP could feed his 240v heater and two 120v circuits with a single multiwire circuit.
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