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circuit amperage for tools.

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  • circuit amperage for tools.

    I'm in the process of getting the shop in my garage up and running. I've already insulated it and installed my flourescent lights. This weekend I'm installing the heating system. The only thing left to do is wire the plugs. I'm going with a 60 amp subpanel since my current 100amp panel is almost out of room. My lights will remain on the circuit that they are currently on which shares a plug that I plan to use my dust collector on. For the rest of the tools, I need to decide wether to wire 15amp or 20amp. For the table saw (Ridgid 2412), I figured I'd use 20 amp. What about the rest of the tools. I own all Ridgid and have the bandsaw, planer, jointer, drillpress, 12" miter saw and osciallating sander. I figure I'll probably split all of the plugs in my shop onto two circuits, a 20amp and a 15amp circuit.

  • #2
    My two cents... don't even mess with 15 amp circuits. Make all outlets 20A with #12 wiring from the breaker to the outlet. The cost difference between the two is minimal. 15A breakers with #14 wiring should only be for lighting. I know the NEC allows you to use 15A receptacles but you will notice the voltage drop with #14 wiring each time you start a tool. If you are already adding the sub panel why not put some in 240V recepts and convert the tools over? There are several postings on the benefits of going 240V so we won't belabor that here.

    I am sure some of the Electricians will chime in with their thoughts but this is one Electrical Engineer's perspective.
    \"It is better to be careful 100 times than killed once\"<br />Mark Twain


    • #3
      I just finished my third garage shop and here is what I have done.
      Ran AWG 8 from a 40 amp breaker on the main panel to an 8 breaker pony panel in the garage. Run 12/2 for all the plugs (don't be stingy on the plugs). Now you can use a 20A breaker with 12 AWG wire but you should use 20A plugs as well and they tend to be expensive unless you need one for a small welder or compressor. the 20A 110V plugs look like -&#0124;&#0124; and the 20A 220V plugs look like &#0124;&#0124;-. If you use regular 15A plugs you should use 15A breakers, the purpose of the 12 gauge wire is to lessen the voltage drop when starting large tools the tools don't require a 20A breaker.
      I have 12 110V plugs and 7 220V plugs in the garage this may seem extravagant but for the cost of a plug put lots in, every tool is mobile and I can plug it in anywhere without the cord being in the way. I would suggest that you convert any tool that is capable to 220V as it will run cooler (changed my RAS to 220 and it runs much better). Don't forget atleast 2 plugs in the ceiling ( GDO and air filter). Another thing I have found useful is at least 25 feet of 12 AWG SJOW hard wired to an octogon box with a plug on the other end. Now you have an extension cord than can't be lost or borrowed. Don't scrimp on the light either I use 8 dual tube 4' flourecents in my 2 car garage, it is like daylight with very few shadow areas. As a final thought finish the walls with drywall, tape them and paint them with a white semigloss, great for light reflection and the dust tends not to stick to it. I lied one last point, do the floor in epoxy paint this is the first garage I have use it in and the stuff is wonderful all be it a PITA to prep and dry.


      • #4
        I think I will make the conversion to 220V for the tools that support it. My bandsaw, Jointer and dust collector support dual voltage. I'll run a separate circuit for the dust collector and keep the bandsaw and jointer on the same one. For the rest, I'll use 12 gauage wire. Do 20 amp plugs have a different interface than 15a plugs? I thought they were the same but the 20a just had the higher rating. My lighting is good. My shop is only 25 x 11 and I have a dual 8' and two dual 4'. Its like a tanning salon [img]smile.gif[/img] I'd rather need sunglasses in the shop than be straining my eyes from poor lighting.


        • #5
          I agree that 12g 20A circuits are the way to go, my 2 cents would be that the first outlet in each circuit should be ground fault interrupters. The 20A outlets that have a "T" sideways for one prong mean that the outlet is a 20A dedicated circuit, meaning that only that outlet is on the line all the way back to the box.Putting two or more of those outlets on the same circuit is a no-no, at least around here.
          \"Is it Friday yet?\"


          • #6
            the 20A plugs have the same screws on the side but the common (left from front) side of the recepticle will accept the standard verticle prong or the 110V 20A horizontal prong.
            While you are building perhaps add a hefty exhaust fan for when you run cherry though what you thought was a sharp blade or MDF to evacuate the dust/smoke


            • #7
              I'm settled on running all 12-2 BX for my wire. Even for the 15 amp plugs. I wish I could change my TS voltage to 220 but I can't (its the 2412). If I go to a 20amp circuit for this, should I change the wire on the motor and put a 20amp plug on it? Or will it be fine with what it comes with?


              • #8
                The plug and cord assembly on your saw is fine as is (unless there is some damage).

                CrookedCut brings up a good point on the GFCI outlets. Per code receptacles added to a garage shall be GFCI. You can put standard receptacles down stream from a GFCI receptacle but be carefull to limit them because if the GFCI fails then all down stream receptacles are dead.

                Question for CrookedCut .... why is a "T" pronged receptacle dedicated? Haven't heard that one before. My understanding for the "T" type is that it allows two different configured plugs to work in the same receptacle.

                A 20 A receptacle will fit a 15 or 20 amp plug. A 15A receptacle will only take a 15A plug. The neutral blade (white wire) on a 20A plug is rotated 90 degrees and that is why on a 20A receptacle you will notice the "T" shaped slot. When changing your tools over to 240V make sure you put in receptacles and plugs that have the hot leg (black wire) slot and tab rotated 90 degrees... that way you don't accidentally plug the wrong tool into the wrong outlet.

                Keeping your minimum wire size at #12 is great.

                The code requirements listed here are per the US NEC and Canada may have some differences so make sure to check with someone local that knows your local code requirements.

                Make sense?

                [ 01-14-2004, 09:58 AM: Message edited by: RSHugger ]
                \"It is better to be careful 100 times than killed once\"<br />Mark Twain


                • #9
                  Ol'CrookedCut... I think I answered my own question. If you have a 20A circuit, with a 20A rated receptacle and a cord operated device with a 20A plug, then you will probably have a load that maxes out the single 20A circuit. Therefor you don't want a bunch of other receptacles on the same circuit that would then push you over the limit and cause popped breakers.
                  \"It is better to be careful 100 times than killed once\"<br />Mark Twain


                  • #10
                    My lights will remain on the circuit that they are currently on which shares a plug that I plan to use my dust collector on.

                    You DO NOT want to do this. Make sure that your light circuit is not shared by ANY tool circuits. Not a good thing to trip a breaker and have the lights go out while a blade is still spinning. Just my .02
                    -Rob<br /> <a href=\"\" target=\"_blank\"></a> <br />Damn, I hit the wrong nail again. Ouch that hurts


                    • #11
                      The GFCI thing sounds familiar and makes sense to some degree if you are dealing with a moist climate. I'll have to check the code for Canada. I'd rather not bother with GFCI. My garage should be as dry as my house.

                      RSHugger, not sure I follow your logic on only allowing one T shaped plug on a circuit. Your argument would hold true for 15 amp as well. I mean if you have several tools plugged into 15amp plugs on the same circuit and they all draw close to 15amp then you will blow the circuit.

                      As for the lights on a separate circuit, yes that makes sense, but I figured the dust collector would have a fairly consistent load. Not like a table saw that has to work really hard when you try and jam some really hard wood through it. My dust collector was on the same circuit as the lights in my old shop and I never had any problems.


                      • #12
                        I should have allowed my grey matter to fully awaken before trying to carry on a meaningful response [img]redface.gif[/img]

                        Okay... since I mainly deal with big power projects I had to break open the code book to refresh on the receptacle loading. Still not sure what Ol'CC is talking about in regards to the "T" faced receptacle.

                        Just keep in mind that if you have a 15 amp receptacle that the largest load that you can plug into it is 12A. A 20 amp receptacle will allow you to plug in a 16 amp load. The combined loads (operating) for all of the plugged in devices on a single 20A circuit can not exceed 16 amps. You probably are not going to have all of the equipment in your shop running at the same time so you are only looking at your typical, running loads and it sounds like you are planning on minimal receptacles anyway per circuit.

                        The code book rationale for putting GFCI breakers in the garage is that since garages are at or near grade that you can get water on the floor and also that you could take and extension cord from the garage and run electrical appliances outside... personnel protection.

                        Have I thoroughly confused everyone
                        \"It is better to be careful 100 times than killed once\"<br />Mark Twain


                        • #13
                          Its clear to me. Just in reference to the home run 20A plugs, I did see that once in a warehouse computer room but the plugs were orange.


                          • #14
                            Just to try to clarify mine own experiences: When a plug has the one vertical and one horizontal prong on it, it is that way because it draws in excess of 15 amps as others have stated. The corrisponding outlet is also that way so that they can work together.(obviously) So, the equipment I install (Xerox machines) draw 16 amps. If the circuit is 20 amps and my machine draws 16, only one outlet should be on that circuit, thus a "dedicated circuit".
                            Maybe the code allows you to have as many of these outlets as you want on the same circuit, I don't know for sure, but I do know that it is very poor design to have one of these outlets in a wall, plug in your machine, and when turned on, have three complete offices and the overhead lights for them all go "POOF!!"
                            That is a true story. If someone is designing a office "copy room", those outlets always are dedicated as copiers cannot share the same circuit even if the amps are there, because the RF interference between their power supplies is noisy! (do your overhead lights hum and go "Boing"? theres a clue for you)
                            I also have seen the orange outlets, I'm sure someone else on this board knows better than I, but I believe they are used to show something special for computers like GFI or battery backup, etc.
                            I will state that I am not certified for anything electrical, I have taken several college classes to help with my job, so feel free to correct me, its been 20 years since those happened!
                            \"Is it Friday yet?\"


                            • #15
                              Hey a fellow toner eater! I do the printers for the competition. If you check the install and planning guide for the copier it will suggest a separate cct due to current draw just as it is suggested that fridges and freezers go on a separate outlet but it is not code to do so.