I keep hearing that adding a 220V circuit for a table saw is expensive. As I am adding one myself I thought this might be interesting to share:
Siemens Q230 30A 2pole breaker -US$9.48
2#10 Romex with ground 100 feet -US$80
Leviton #55054 30A 2pole -US$10.91
With a few dollars added for cable supports and tax this would still come in under $120. For something no more complex than adding a 120V 20A dedicated outlet I would not bother with local authority approval or inspection (Scratch this sentence – I now understand inspection is required and for the low cost involved it is certainly worth it)
For my small one-man shop I’m considering adding other 120V circuits so could put in a load center (Siemens 125A MLO $22.94) 50A 2P feeder breaker (Siemens Q250 $9.48) 100 feet #8 Romex (Southwire $175) plus say $100 for 4 branch breakers, 4 outlets and branch wiring (only one circuit is 30A 2pole) within the workshop would cost about $310 for material.
Well that is not so cheap! I might be simpler to put in the 30A 2pole table saw circuit plus a dedicated 20A circuit and have all the power I will need for around $150
There is no need to run a 100A feed to the load center as it’s feed is sized based on connected load plus load factors and allowances out of the National Electrical Code, and not on a sum of the breakers it contains. Three 120V 20A dedicated outlets = 4500VA, 3hp say 3500VA, +25% of 3500= 8875VA = 38 amps at 230V, well within 80% of the 50 amp feeder.
Edited 4/15/2006 7:42 am by GaryPC
Replies
Don't forget the building permit and inspection fee. For me, that was about $20 IIRC.
EDIT: I'd not noticed you said you wouldn't bother with the inspection. To each his own, but there are two reasons I recommend it. 1) If you don't, and there's a fire, your fire insurance may well refuse to pay. 2) If you're not an electrician, and you make a mistake, you may make a mistake that causes a fire -- see #1.
Edited 4/13/2006 4:32 pm by John_D
Yes I agree about inspection for adding a subpanel, and I no doubt it wouldn't hurt for even a single outlet. I have no idea what the inspection fee would be for such a small scope of work but if it is $20 count me in!
Your post is rather confusing to say the least.
You start by explaining you want to add a 220v circuit and then refer to 120v circuits in the remainder of your post.
Regardless, if you already have the space available on your main panel to add in all the circuits you need, and the runs aren't too long from the panel to the shop, you are correct, it's not too expensive.
Keep reading the Electrical Code book, you will probably find it telling you that you are allowed one plug per 220v circuit. If you want/need three 220v plugs for your shops saw, DC, jointer et al, that alone equals 60 amps and six free slots on your main panel just for the 220v. circuits alone.
This is why most of us need to upgrade our main panel to 200 amps and have a shop sub panel of at least 100 amps.
You are correct in your calculations, as long as an inspector doesn't see it. You are picking and choosing what you want from the electrical code to suit your needs, but hat doesn't make it up to code however. If you run your saw and DC at the same time on the same circuit, enjoy the many "trips" to and from your panel.
Electricty sucks.
Santa Barbara,CA
Edited 4/13/2006 4:44 pm ET by SantaBarbaraSawDust
I wasn't very clear was I.
Fortunately I only need one 220V outlet for a table saw, everything else is 120V presently fed by a single circuit. While adding the TS outlet I considered a subpanel as it could provide additional 120V circuits over the one already there. This could come in handy when my planned 120V 1-1/2hp dust collector arrives and I use it with a 120v tool
However seeing the higher cost for a subpanel I'm leaning towards simply adding a dedicated 120V 20A circuit in additon to the 220V outlet. This is enough for me in my small one-man shop
I've never tried to put (2) 220V outlets on a single circuit -all the same where in the NEC are you reading that it is not allowed? I'm not saying it isn't there, however 2002 NEC 210.23(B) almost suggests otherwise...
(B) 30-Ampere Branch Circuits. A 30-ampere branch circuit shall be permitted to supply fixed lighting units with heavy-duty lampholders in other than a dwelling unit(s) or utilization equipment in any occupancy. A rating of any one cord-and-plug-connected utilization equipment shall not exceed 80 percent of the branch-circuit ampere rating.
Having said that I have designed the electrical systems for many workshops and always have one circuit and outlet per machine. Even the 120V stuff I allow for all machines being used at one time. But this is in large workshops up to 40,000 sq.ft. For a one-man shop in a residence wouldn't it be good to share the circuit. That the machines we are talking about are plug-in type and often considered somewhat portable why should they be treated differently that 120V?
I didn't find a requirement in the NEC that 220 circuits can only have one receptacle. But my inspector said it was a requirement in my city.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
If you have wired 40,000 square foot shops, you wouldn't be on this board asking questions.
If you need only one 220v outlet, and your panel has 2 available slots, by all means, go for it.
As far as putting in multable 120v outlets in a "one man shop" with one tool in use at a time, you can space them 4" on center if you like.
Terry
Santa Barbara,CA
I haven't wired any, I design electrical systems for a living. My original post wasn't a question I was simply sharing something. And for this effort on my part I have already learnt that maybe having inspection of my installation work of even just one outlet in my residence is probably not an expensive proposition. The second thing that might be valuable if ever needed I got from your comments - if I want other 220V outlet(s) I might be able to extend from the one outlet already installed. Brilliant stuff!
>if I want other 220V outlet(s) I might be able to extend from the one outlet already installed. Brilliant stuff!
OK, I understand what you are doing, and I understand you very well could have enough power from one 220v circuit to power two 220v tools, per your calculations.
What you fail to grasp per the Electrical code, is the need to allow for the nimrod property owner after you are gone.
We can all do the calcs, but the codes allow for the guys after you who don't understand.
Terry
Santa Barbara,CA
Terry - I make a good living because of my grasp of the National Electrical Code. I request that you look at offering or at least present a little more respect for other posters who per chance might acutally know what they are talking about.
Yes that last sentence was a dig. My apologies, sarcasm is a life long weakness of mine, and I enjoy it way more than I should.
Gary
Edited 4/14/2006 7:55 am by GaryPC
Last time I got a electrical permit to wire a shop it cost me $15.00 for the permit, no ADDITIONAL charge for (two) inspections (made mistake requiring a second inspection). I am NOT licensed electrician, my dad was & who taught me, but I obtained permit and did work as homeowner. My contractor buddy talked me into getting the electrical permit/inspections, explaining if next owner had electrical fire with work I did, I was legally liable & could be prosecuted if I didn't get permit & have my work inspected and bought off. He said he'd rather build without permits, than wire without permits, less liablility...I didn't want to risk jail...
Jeff
I've heard about that but I'm not sure where. It might be in the paperwork associated with the selling of a residential property where the seller promises that all work has been permitted to their knowledge. $15 -what a great price to protect against some future problem. I've heard of inspectors charging for re-inspection it sounds like you got a good deal. I will definitely look into this for any work I do, come to think of it I installed a GFI outlet for a fountain that could use some looking over!
I just checked the Labor & Industries website here in the state I live in, they handle electrical permits and inspections for most of the state (some cities have their own inspectors and policies, if you live in these cities they are the local authority).
In general, permit/inspection cost for a new or modified 200 amp service (it's priced by total amperage of the service) can be done for about $65-$75.00 and the permit can be purchased online at the L&I website. How hard is that?? I don't know where you live, but check with your state Labor & Industry dept. if you decide to go this route.
Jeff
I'm in Northern California -as I start to explore this on the net in Nevada County it is not looking too much different from what you describe. I am used to seeing thousands spent on permits by contractors because of the commercial projects I do electrical engineering for (it's my job) and mistakenly assumed the costs for small project inspection would at least be in the hundreds - more than the work itself! -but I'm real glad to be wrong about that.
So ... I will definitely go this route and get everything inspected ...thanks
Gary
Gary,
I at times am too blunt with how I say things, please accept my sincerest apoligies to you, I didn't mean to insult your intellegence.
Please also know that I understand the calcs you put forth and for the most part, I agree with what you want to do regarding the power needs to your shop.
I'm not taking exception to how you are doing your elec., I was refering to what the code provides, in order to keep the Hilton sisters (or anyone else that has a straight line brain function) from sticking a hair dryer into a 220v plug without killing themselves. And yes, I have seen this happen, as well as another fool pugging in a bare wire Java Lamp cord into a 220v plug (he said the plug was "goofey") and in turn burned his house to the tune of over $10, 000.
The fact is, the Electric code, at least in L.A. County where I work, doesn't care about anyones formula. The code is written to protect the Paris brain dead Hilton's of the world safe who will try screwing in a burned out light bulb with a Monkey Wrench.
With that said, I'm done.
Terry
Santa Barbara,CA
Hey Terry thanks for your response that was generous of you. Yes last I heard there are 40,000 fires a year in the US caused by faulty electrical systems -it sure is something not to be taken too lightly. None of us can ever understand enough to be completely safe, so we all do our best. kind regards- Gary
Can anybody explain the reasoning for only one 220V plus per circuit?
It appears that the NEC allows more then one, but the local bylaws restrict it. Where I am we are allowed multiple plugs per 220V circuit, and I was wondering if there is a specific danger related to it.
My shop has two 220V circuits the first has 3 plugs (jointer, table saw and lathe) and the other has 2 plugs (dust collector and an alternate location for the DC). I had an electrician install the wiring, and it was inspected by the city so I know it's up to code. (Note: I do live in Canada, so the codes are clearly different).
Local codes may have more stringent requirements than the NEC.I ran afoul of this some years ago when I ran several lines from the breaker box to the rear of the shop, called for an inspection and discovered the county required the next gauge up from the NEC for a run that length.Lesson learned: Speak with local inspector first if you're not a pro. Leon
If you Google "voltage drop calculator" there are online calculators where one can see how far a particular gauge wire can be run.
To get the amps, for a single outlet on a dedicated circuit the rule is 80%, i.e. 20A = 16A and 30A = 24A. According to my software, and using 3% as the limit, #12 copper is good for 59 feet at 16A/120V; and #10 is good for 120 feet at 24A/230V. But if an outlet is dedicated to a particular piece of equipment and this equipment were less than the 80% you could use the lower number. For example a 14A unisaw could be fed by 205 feet of #10 copper. For multiple general convenience 120V outlets each outlet is worth 180VA (1.5A). 6 of these outlets =9A, this with #12 copper is good for 105 feet. I've run longer circuits than this by not following the code recommended voltage drop, afterall voltage drop is generally a code recommendation and is not an actual requirement. But most people do not think of this so it is a hard one to convince inspectors on, but it can be done! Another way to get greater run for your copper is to calculate the voltage drop from the point of service. With 5% total loss being the recommended maximum (that most inspectors enforce) if you can show that vpdrop prior to your panel is 1%, you could use 4% as your limit for the branch circuit.
http://www.ecmweb.com/mag/electric_calculating_voltage_drop/index.html is a good primer on this stuff
Generally I don't find that local codes are more stringent than codes. Actually there really aren't any local codes, just local interpretation of State and national codes. It is more likely that someone involved (inspector or electrician or engineer) didn't understand the code fully.
Hope this is somewhat useful?
Gary
AS I understand it the concern is that the circuit is overloaded. But there would not be any real danger provided the breaker trips when it should
I assume your normal circuits are 120V? In some countries 220V is used for regular household circuits
Hey Terry, Is it true that you can only have one plug on a 220amp circuit? I'm in an industrial park and I have like 4 outlets on one 220 amp circuit. Only one piece of equipment is running at a time though.
Thanx, Lou
Leon's right, sometimes local code (or enforced practice, nod to GaryPC) is more strict than the NEC requires. There's no joy in being "right" about the NEC's requirements, if the inspector still makes you rip it out and do it the way it's done in your town. :)
The best and only authoritative answer on this issue will come from your (city) inspector. As many have pointed out, there's nothing magical about 220 that makes multiple outlets bad. But more than one person in this forum has found that their locale requires homeruns for every 220 in residential installs.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
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