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Thread: Electric Service

  1. #1
    Join Date
    Jan 2012
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    Bumpass, VA
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    35

    Electric Service

    The new shop is going slow but well, foundation is in, and floor has been started, I have pictures and will post in the shop tours in the coming weeks.

    This weekend I met briefly with the electrical consultant, now he hasn't seen the plans yet, he's coming out to the house next week to look at them and the site. But he was questioning why I was looking at 150 or 200 AMP service. Now my old shop had 100 AMP service and I had no issues with power. It's a one person shop where the most I'm going to have running is a tool, dust collector and lights and heat pump. The dust collector, cabinet saw and heat pump are the only things running off of 220, all of them only require a 20 Amp circuit. The running AMPS on the saw is listed as 13, Dust Collector at 13, and Heat Pump at 6.7 Amps. Not sure what the AMP draw for the fluorescent lights are, but I can't imagine that I would be drawing more than 40 AMPS off the panel at once. That gives me plenty of breathing room. Now these three items are the only tools that were not in the old shop. Everything else runs off 110 and was in the old shop. The old shop before trying to cram everything in a one bay garage was 432 square feet. I had a contractor's saw in there, and heated with space heaters and cooled with a window unit. As for the heat pump in this shop it's one of the DC Inverter heat pumps. I have a smaller unit installed in my office even though my office is in a converted attic on the third floor, it will freeze you out in the dead of summer without even trying.

    The cost of getting 150 AMPS out to the shop from the house is nearly double what it would cost for 100 AMP service. 150 AMP is essentially a service feed and not a subpanel feed, so not just the wire being more expensive, but I'll have to add disconnects and other components, assuming I can find a 150 AMP main breaker for the box in the house. The house only required 200AMP service, but I had them put 400AMP when they built the house, but the electrician thinks that's an awful lot to pull off the house panel. At either 150 or 200 AMP he stating the cost would be high enough that it may justify a second meter. That's going to get into costs and headaches I'm not sure I want to go with, namely I'm going to have to go back to the county and redo the permits for a separate electrical source instead of feeding off the house and there is a minimum charge for electricity use each month that I may never hit, so I'll end up paying a higher electric bill than I would need to. I don't plan on doing production work, at 640 square feet room is not that big for tools that would draw extreme amounts of Amperage. I know the reason to increase the power now is in case I change my mind and want to upgrade something later, but I'm thinking stay with 100 AMP for now and if I do make a change, just apply for a service upgrade permit and have the utility company come later and put in 200AMP service off the main power grid.

  2. #2
    Join Date
    Nov 2012
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    Wapakoneta, OH
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    611
    I would say that's a good plan. It's also the one I'm using with my shop, I have 100 amps from the house panel and if I need more (which may be soon) I'll add a second meter. But the increased need isn't from my shop, I have a pole barn about 150' away that only has a 15 amp cirsuit from the shop panel. It's not even enough to run an air compressor I keep there so I'd like to have a panel in it as well, if I do that I'll add a service to the shop and run a sub panel to the barn. Anyway, back to the lights; I have in my 750 sq. ft. shop 10 fixtures with 4-32 watt lamps and 1-2 lamp fixture and they are all one one dedicated 15 amp circuit. So I'd say you estimate of the current draw for the lights is overly generous.

  3. #3
    Join Date
    Feb 2008
    Location
    East Freeetown, Massachusetts
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    If you are drawing 40 amps for lighting I would say you are lighting a small factory - NOT a one man shop.

    I have a 30 amp breaker as a main for my shop of almost 700 sq-ft.
    I have jointer - Planer - table saw - DC - CNC machine - lights - lights - router table - lots of hand tools - radio - computer - a/c

    I will run the CNC my dust collection - lights - radio - 2 window A/C units and a power tool or 2 like a tablesaw - AND, a ROS or something. WOW - how may tools can I have going at one time.

    My ENTIRE house including shop is 100 amp. So - summertime - in addition to the shop running I have 3-4 window A/C units, computers, lights, TV. Maybe even the electric dryer.

    I have NEVER popped the 100 amp breaker. For that matter I have never popped a breaker due to too much load.

    Sooooo -- to ME ----- you do not need a 150 for the shop - at least NOT for the load.

    ALSO - you do NOT - repeat - you do NOT need dedicated circuits for your band saw - table saw or anything else.
    I OFTEN will be running my table saw AND my Jointer both under load (when my friend is in the shop with me). I have done that on purpose just to see.

    ALSO - you do NOT need a 30 amp 220 breaker to feed a 9 amp draw 220 band saw. Still do NOT need a dedicated circuit.

    Also - you CAN feed several 220 devices on one 220 breaker.

    Now - the ONLY reason to go 150 or 200 is to have a larger circuit box with more breakers.

  4. #4
    Join Date
    Jul 2011
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    The Gorge Area, Oregon
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    Quote Originally Posted by Leo Voisine View Post
    Also - you CAN feed several 220 devices on one 220 breaker.

    Now - the ONLY reason to go 150 or 200 is to have a larger circuit box with more breakers.
    Some inspectors/jurisdictions won't allow multiple outlets per 220 breaker. There isn't any technical reason it won't work, but rules are rule are rules and sometimes its just easier to get it done without fighting the man

    I would put in an oversized breaker box if we can (there isn't any - again technical specific inspectors/jurisdiction may have other ideas - reason you can't put in a 200 "amp" sized panel with 100amp feed).

    For lights a T8 bulb only takes ~32-34 watts or about 0.3 amps (at 120v) per bulb (that's per bulb not fixture) but the bottom line is that you can put a whole lot on a single 15 or 20 amp circuit (and it likely won't be fully utilized unless you're shop lit up like the sun). Consider putting some lights on a separate circuit so you can have lights if you need to turn one off for maintenance.

  5. #5
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    Jan 2012
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    Bumpass, VA
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    Ok, I think I need to clarify my statement, the 40 amps was total, Cabinet Saw, Dust Collector, Heat Pump and lights, not 40 AMPS just for the lights. I'm fully aware that this is pushing all the tools to the maximum capacity, and not the normal usage.

    At the moment, the only 220 machines I have is the saw, collector and heat pump. Those three will probably be on dedicate circuits, but if I get more 220 machines, I would probably extend the circuit to other tools. The rest of the tools are 110, I do plan on splitting the 110 outlets in the shop into 2 circuits and possibly a third for outdoor outlets that I can shut off at the panel when not needed, still undecided on that one.

    GE Makes a 100 amp panel that will take 32 full size breakers, that's the same brand of panel they put in the house, I may go with that just to not have to worry only breaker space. I don't have that many circuits planned.

    Thanks for the insight, I'm feeling better about dropping down to 100 AMPS.

  6. #6
    Join Date
    Feb 2008
    Location
    East Freeetown, Massachusetts
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    I am not opposed to following rules.

    I would like to see the electrical code that states not to put multiple recepticals on one 220 breaker.

    I just see too many time where a home installation of a 30 amp dedicated circuit in installed to feed one machine that draws 9-10 amps - because - the installer "heard" that was what he was supposed to do.

    I am ALL for following code to the T.

    I don't have an electrical code book - but I would LOVE to KNOW the code on that point.

  7. #7
    Join Date
    May 2007
    Location
    Thomasville, GA
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    I have a fairly well-equipped shop that measures 36' by 24'. An 8000BTU window type A/C is all I need, when I use it. The electrical contractor I used ran 100A service from the distribution panel on the side of our house to a subpanel with 30 circuit breaker positions in the shop. I've calculated my worst-case current draw at less than 65A if I'm using my 3hp table saw, 3hp dust collector, A/C is on, all 20 two-lamp fluorescent fixtures are on along with a couple of box fans. I suppose I could turn on both bandsaws, my planer, jointer, sanders, etc., to see if I could start popping things, but.....

    If you add up the circuit breakers (220 and 110) in my shop panel, it totals 360A of protection but not everything is on at the same time. I've never come close to an overload situation with 100A service to my shop.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

  8. #8
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    The Gorge Area, Oregon
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    Leo - you're correct but sometimes that doesn't matter Dealing with inspectors is sometimes one of those times... Basically it boils down to whether the inspector decides its a "dedicated motor circuit" or not. Pretty clearly if its a 15 or 20 amp outlet you don't need a dedicated branch circuit above that it starts getting more complicated and somewhat depends on how you read the rules and which version of said rules you're following.

    Quote Originally Posted by Leo Voisine View Post
    I am not opposed to following rules.

    I would like to see the electrical code that states not to put multiple recepticals on one 220 breaker.

    I just see too many time where a home installation of a 30 amp dedicated circuit in installed to feed one machine that draws 9-10 amps - because - the installer "heard" that was what he was supposed to do.

    I am ALL for following code to the T.

    I don't have an electrical code book - but I would LOVE to KNOW the code on that point.

  9. #9
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    Quote Originally Posted by Ryan Mooney View Post
    Leo - you're correct but sometimes that doesn't matter Dealing with inspectors is sometimes one of those times... Basically it boils down to whether the inspector decides its a "dedicated motor circuit" or not. Pretty clearly if its a 15 or 20 amp outlet you don't need a dedicated branch circuit above that it starts getting more complicated and somewhat depends on how you read the rules and which version of said rules you're following.
    I would challenge the inspector against code all day long.

    Inspectors do not right the code or the law.

    I don't want to go political with this. I know CoC forbids political stuff.

    When I got my Contractors license the instructor of the class was a building inspector that shut me down on a job I was doing - then he talked me into getting my license. He said that inspectors will concede to code. In fact they respect that someone will quote the code to them. The problem is that there are too many people that don't know code and try to argue their way based on their limited understanding. He said - stand your ground if you clearly know what the code states.

    On another situation - a less than knowledgeable inspector was trying to get my friend to do something on his property that was clearly wrong. It was wrong based on the towns codes. My friend was NOT in violation. My friend got the mayor involved and the problem and citation went away.

    I don't mean to be argumentative Ryan - but it does matter. Do the work to code - KNOW, what you are doing. Do NOT ever let inspectors create their own laws.


    If we can have 2-3 or more machines on a 110 circuit. Why would that be different on a 220 circuit?

    Still I would LOVE to see the code on that stuff.

  10. #10
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    Quote Originally Posted by Leo Voisine View Post
    Still I would LOVE to see the code on that stuff.
    I'll do my best although I don't have access to full code books easily (I'd have to go lubricate some folks to let me have access to theirs and no I'm not buying them - expensive much ).

    There are a couple points of contention.

    First is section 210 which gives you a fair bit of leeway if you are putting in 15 or 20 amp circuits and would probably be your first point of rebuttal if challenged.
    210.23 Permissible Loads.
    (A) 15- and 20-Ampere Branch Circuits. A 15- or 20-ampere branch circuit shall be permitted to supply lighting units or other utilization equipment, or a combination of both, and shall comply with 210.23(A)(1) and (A)(2).
    (1) Cord-and-Plug-Connected Equipment. The rating of any one cord-and-plug-connected utilization equipment shall not exceed 80 percent of the branch-circuit ampere rating.
    (2) Utilization Equipment Fastened in Place. The total rating of utilization equipment fastened in place, other than luminaires (lighting fixtures), shall not exceed 50 percent of the branch-circuit ampere rating where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.

    A lot of the sticking points land around whether the circuit is "dedicated use" or not and if so what sort of dedicated use. Most of the interesting details are in NEC 430.24, 430.52 and 430.53 which define when and how a single branch circuit can be used for "multiple motors" at a single time (actually other parts of 430 apply in some cases as well). A lot of the contention here is if most of the stuff we use are considered fixed motors as motor circuits or not (if so they probably need to be individually fused - and if the fuse is on the motor itself you have the contention of demonstrating that that is the case vs having wired in fuses). If the tool is hardwired (i.e. there isn't a plug to remove) the discussion becomes a bit more difficult and you are mostly stuck with one circuit/machine unless you can demonstrate you meet some of the exceptions for allowing multiple motors/circuit (which has sizing and individual overload protection requirements - and there are some free passes for equipment "manufacturer designed" for multiple loads/circuit). The actual rules here are fairly complicated and require a bunch of math to determine if what you are doing is a-ok in the specific instance so I can understand why a lot of inspectors require one circuit per outlet unless you have _all_ your ducks in a row ahead of time.

    You'll also have to convince the inspector that they are "noncoincedental loads" (that is you ain't ever going to turn it all on at once). For something like a tablesaw and bandsaw on one circuit in a garage/one man shop - that could be a pretty compelling argument if rolled up properly. If its something like a dust collector and a air compressor (and combined they exceed the 80% fla rule) you'll have a harder time making the argument (heck I'd have a hard time making the argument to myself ). Part of the sticking point here is that a lot of 220v machinery is designed to use a fair chunk of the circuits capacity (at least on startup) and there is no reasonable way for the inspector to know what you'll actually plug into the circuit and if they could or could not be used at the same time so he is in somewhat of a rough spot (30a and up circuits - I think both 120 and 220v are mostly excluded from some of the convenient 15/20a exceptions on this).

    If you can get ahold of a code book look at those sections and it will soon be completely unclear and you'll soon start to question why you were ever interested in figuring any of this out anyway

    In practice as long as you size the wire and the outlets to match the breakers (wire can obviously exceed) you generally wouldn't have a real problem except nuisance trips. There is some small chance that you would have a bigger problem from a faulty breaker if you overloaded the circuit (back to the "noncoincedental loads" issue - a lot of the NEC is about dealing with "shouldn't ever happen edge cases) and the breaker didn't trip - this is somewhat more problematic at higher amps (thus the expiration of some exceptions above 20a) because well.. higher amps (more fire, more zap).

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