Number of outlets?

[LRod]

My understanding is that in residential there are no limitations, but in commercial there are. My source for that is Rex Cauldwell in his Taunton Press book, "Wiring a House."

[Mike M]

I'm too lazy to look it up, but the general rule is your allowed 180VA per duplex receptacle for circuit calculations assuming its a general purpose receptcle circuit. Depending on the amperage of the cirucuit this would allow 10 on a 15 amp and 13 on a 20 amp. If you have loads that draw enough then they must be dedicated.

Mike M

[russellseaton1]

No. Simple example. Bench is along one wall. Using the mini lathe and shop vav. Mini lathe sits on the bench while using it, shop vac is connected to a large funnel positioned behind the lathe to help get the sanding dust at the source. All plugged into the outlets along the one wall. You have two battery chargers sitting on the shelf beneath the bench plugged into the outlets along that wall. You have the TV going near the bench so you can hear the game or something, not watch it while working. You have a two 150 watt incandescent lamps to cast shadows on the piece you are turning and to help you see. These are also plugged in right by the bench because you are working by the bench. And you have one of those ceiling mounted air filters plugged into the outlets along the bench wall too. Seems to me like you need multiple circuits.

Really only one electrical device is runnig at the same time? Look around and I'll bet you see lots of other electrical devices going at once.

So you did exactly what I said to do. You ran multiple circuits all over your shop. In the above sections you have general use circuits A and B and stereo, air cleaner, and exhaust fan. FIVE circuits. Plus the 220 circuits for the compressor and the saw/jointer/planer and dust collector. Two 220 circuits. And you said several lighting circuits.

You did exactly what I told you to do. Multiple circuits spaced out all over the shop.

[B A R R Y]

Kind of, but with a purpose.

I read your post as making sure that every box has a dedicated circuit. That's a waste without some forethought. If I misunderstood, I apologize.

[LRod]

Setting a suggested value for calculating circuits is not the same as mandating the resultant number as a maximum. I don't doubt that the value is what you say, but I don't believe that it translates to a rule.

I'll continue to wait for a specific cite (although I'm confident the wait will be a long one).

[Pat Barber]

I would use ALL external boxes mounted on the wall using plastic conduit. Shops "never" turn out the way they start and your requirements will change down the road. With the external mounting, things can be changed with little trouble but if the boxes are in the wall, you are screwed.

[e-mail] wrote:

[Tim Douglass]

Three phase is a horse of a different color, and I'm not expert on it at all, but in a normal 2 phase panel (U.S.) you have 240 volts coming in as two 120V legs that are 180 degrees out of phase. In a 240 volt circuit you then have a 240V differential across the two legs. A 120V circuit consists of one hot leg and a neutral, giving a 120V differential. When you do two 120V circuits with a common neutral the two hots have to come from opposite legs so that the neutral never carries more load than one hot. If they come from the same leg the loads add together on the neutral and can easily overload that wire. While this is a common wiring practice and meets code, it is also one that is denigrated among electricians who do repair work, as it makes adding a circuit very difficult.

-- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"

Tim Douglass

[Oughtsix]

If your running metal conduit you will definitely want to run stranded wire. A wires current carrying capacity is based on how much current the wire can substain without melting the insulation. I am pretty sure you will find different current ratings for stranded tth wire and romex in any electrical code book. Stranded in metal conduit can carry more amps than romex in conduit. I also believe that romex in conduit is rated for a lower load carrying capacity than romex in air because of the tendancy for conduit to store heat rather than disipate it into the air.

In any case running two hot legs, a neutral and a ground makes for easily mixing 110v and 220v circuits. In some cases I believe you don't have to run a ground in metal conduit and you can use the conduit for the ground. I am unsure of this though and would reccomend running an uninsulated copper ground. Seperate stranded 12g is a lot easier to work with than romex.

[Mike M]

I stand corrected as far as dwellings and quest rooms per NEC rules. I haven't done anything but commercial in 20 years. Your local jurisdictin may have their own rules. If your building a stand alone shop it may not be classified as a dwelling unit so you have to check with your local inspectors.

(J) Dwelling Occupancies. In one-family, two-family, and multifamily dwellings and in guest rooms or guest suites of hotels and motels, the outlets specified in (J)(1), (J)(2), and (J)(3) are included in the general lighting load calculations of 220.12. No additional load calculations shall be required for such outlets. (1) All general-use receptacle outlets of 20-ampere rating or less, including receptacles connected to the circuits in 210.11(C)(3) (2) The receptacle outlets specified in 210.52(E) and (G) (3) The lighting outlets specified in 210.70(A) and (B)

220.44 Receptacle Loads ? Other Than Dwelling Units. Receptacle loads calculated in accordance with 220.14(H) and (I) shall be permitted to be made subject to the demand factors given in Table 220.42 or Table 220.44.

(I) Receptacle Outlets. Except as covered in 220.14(J) and (K), receptacle outlets shall be calculated at not less than 180 volt-amperes for each single or for each multiplereceptacle on one yoke. A single piece of equipment consisting of a multiple receptacle comprised of four or more receptacles shall be calculated at not less than 90 volt-amperes per receptacle. This provision shall not be applicable to the receptacle outlets specified in 210.11(C)(1) and (C)(2).

[bf]

Suggestion.. I'd make a dedicated circuit for the dust collector. Decide if you are going to use a remote controller or not. I hate remote controls, because I always lose them. So I put 4 switches that control the DC power. It's easy to wire it so any switch can turn the power on or off.

Also, if you are putting two outlets per box, you might want to take the time to wire the right outlet with circuit A and the left with circuit B. That way if you ever want to run two things at the same time, you can plug them in seperate circuits.

Oh yeah, put in about twice as many lights as you think you need. I'm a big fan of those 8' shoplights. They are a little pricey, but they are better than the cheapo 4' ones that have a short lifespan.

[bf]

My electrical inspector said there was no limit, it was up to the installer to estimate the load and install the appropriate amount of outlets.

I wish there was a limit though. My lazy builder wired the 3 rooms of lights, plus the outlets for 2 rooms all on the same circuit.. Kind of a bummer to turn on the printer and have three rooms of lights dim.. Had to run some new outlets myself.

[Pat Barber]

[Mike Marlow]

And the last I knew NEC had a limit of 12 per branch circuit. I have to admit that I don't have an up to date copy of the NEC, so that may be dated information.

[Lew Hodgett]

RE: Subject

See my earlier post, "Electrical Distribution For The Shop"

Lew