BenMinshall

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About BenMinshall

  • Rank
    Apprentice Poster
  • Birthday 07/27/1982

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  • Gender
    Male
  • Location
    Mason, MI
  • Woodworking Interests
    Furniture and cabinets.
  1. Exactly right. It's a reasonable interpretation for him to decide the DC is a "continuous load" per NEC definition and require the separate circuit. One could do some code gymnastics to decide otherwise but I think he made the right call. Some local jurisdictions would consider any building with three phase service to be commercial, so you might have gotten a bit closer look from the inspector than a typical residential shop might. In fact a lot of power companies will not even install a three phase service to a property unless it is zoned commercial land.
  2. That isn't exactly right -- you can't directly add up amperage from 120V loads and 240V loads. You have to convert to power (watts) to get an aggregate draw on the service or do a circuit-by-circuit analysis for the panel box. Remember the service to the building is a split phase 240V/120V at 50A so it is actually capable of powering 100A of 120V loads or 50A of 240V loads or some combination of the two. I think you meant to say power. A motor that can be wired for either 120V or 240V will draw half the amperage at 240V. The power (watts, horsepower) will be the same at either voltage. This is one of the advantages of wiring motors for higher voltage. You get the same power, but when the amps are lower the motor will run cooler thus extending the life of bearings and lubricants. In a 120V circuit, the same current flows in the hot and neutral wire. Both the white and black will carry 20A in this case. In this case both the red and black wires each will carry 10A, and the white neutral will not be used. A 240V motor does not use the white neutral wire. That is one way to think of it, but to be clear the two 120V components are not independent. It is actually a 240V service which is split in two halves. BTW, I'm not trying to pick on you Carl. It's a complicated topic and I'm attempting to clarify the concepts to avoid confusion. I'm glad your shop came out so well. I look forward to the day when I can build my own shop space rather than squeezing into the garage.
  3. A 30A circuit is far too big for a 2HP motor. The 2HP jointer draws about 6.5 amps (1600W / 240V) which means it should have a 15A breaker on the circuit. NEC requires that breakers for motor circuits be no larger than 200% the actual draw of the motor (in some rare cases 250%). Because there are no 10A breakers, you go up to the next available size of 15A. This size circuit can be run with wire as small as #14. There is no problem with using #10 other than it is unecessary expense.
  4. It is always best to look at the manufacturer's nameplate on the machine to figure the electrical load. The sales department is often very generous with the HP rating printed on the front of the machine; the nameplate on the back will be much more realistic. There are two critical numbers to look for: minimum circuit ampacity and maximum overcurrent protection device (OCPD). The MCA is used to determine what size wire must be used to supply the machine and the max OCPD is the largest allowed breaker (or fuse) to protect the machine's circuit. The other important number to look for is the full load amps (FLA) or service load amps (SLA). This number tells you how many amps the machine will pull under heavy operating conditions. NEC requires a main disconnect for a subpanel in a detached building if the subpanel has more than 6 throws. A subpanel in the same building as the main does not require a main disconnect regardless of number of handles in the sub. The NEC does not require breaker coordination for residential services. Without a detailed engineering study there's really no way to know which would trip first anyway even if the amp rating are matched or tiered. The short-circuit trip component of the breaker trip mechanism is largely unpredictable. Main breakers absolutely do trip -- mouse gets into the panel and shorts the buses, landscaper runs a ditch witch through the feeder cable, branch circuit breaker fails and melts to the bus bar, etc.
  5. Hi Jwest, At a 150-200ft distance you are going to want to upsize the wire a little bit to compensate for voltage drop, probably up one size. For example a 60A panel would normally require #6 copper wire, you should run #4 copper. My recommendation is that a 60A panel and feeder would be adequate for a one-map shop, but if you have extra room in the budget go ahead and install a 100A panel and feeder if you think your shop might expand. A reasonable compromise is to install larger conduit and a 100A subpanel with only 60A feeder from the house; if at some point in the future you need more power in the shop you can simply repull larger wires in the conduit and replace the feeder breaker. Conduit is quite cheap so it doesn't cost much to upsize now whereas the larger wire could add several hundred bucks that you may never need to spend. Talk to your electrician about this and get a quote for both 100A and 60A panels; explore conduit vs. direct burial cable -- for example a 60A panel in pipe with copper wire may be more expensive than a 100A direct burial aluminum cable. Some local codes may come into play as well which favor one option over the other. If you're a DIY kind of person, most electricians will be happy to let you do grunt work like digging trenches and installing pipe to save on your overall bill if you're so inclined. If you want to do a rough calculation of what size panel you need and what size you might want, add up all the watts of everything you intend to run at the same time (lights, A/C, tools, etc). Divide that by 240 to get the minimum required amperage of the panel and then leave room for about 20% on top. Use 750W per horsepower if you're calculating motors. An example of largest tool, dust collector, lighting and window A/C unit: 3 HP table saw (2250W) + 2 HP dust (1500W) + 10 32W fluorescents (320W) + big window A/C (2000W) = 6070 W 6070 W / 240 V = 25A 25 A * 120% = 30A The absolute minimum size panel needed to run these items is 30A. Of course a typical shop will have some additional misc stuff you forgot in the calculation and it never hurts to leave a little extra room for motor startup. In this case I would tell the client that if they need the lowest cost option they should install a 40A panel, if they can afford some future flexibility go with 60A and if they want a premium installation go with 100A.
  6. Approximately how far is it from the main panel in the house to the subpanel in the barn? I assume you want to plan to be a one-man shop (e.g. one major tool on at a time)? Do you want to plan for HVAC or hot water in the shop?
  7. When I got mine through the rebate it was only about a week before the mobile base arrived via UPS. Adding the mobile base after the saw was assembled was really no problem. Just undo two bolts from the two legs at the end of the extension table and fold them up. Tilt the motor over to the 45 degree position and the saw will be really easy to tip up to the side and balance it on the end of the rails. This provides plenty of access to install the casters and lifter mechanism.
  8. It depends a lot on exactly what kind of furnace (and probably water heater) you have. It is very dangerous to seal off a gas or oil burning appliance if it does not have access to a fresh air supply that has been sized to match the BTU of the burner. The burner must take in enough air to completely burn the fuel and to create enough draft for the exhaust to make it out the flue. If this doesn't happen, carbon monoxide can build up in the house which is extremely dangerous. I would strongly recommend you consult with an HVAC installer in your area to perform a "make-up air" calculation for the BTU of your furnance and water heater before sealing off a room which contains the furnace or WH. The various permutations of burner type, efficiency, size, building construction, etc are really too complicated to get into on a forum. Some furnaces (like a 96% AFUE) can be completely enclosed whereas others like an 80+ need a pretty signifcant amount of square footage to draw air from. Very few gas water heaters would be okay in an enclosed space.
  9. BenMinshall

    Red Elm

    This is a table I built out of Elm. I didn't find it to be that enjoyable of a material to work with compared to maple, cherry or other domestics. The 2.49 price doesn't strike me as all that great either. I got this batch of elm for free, but after having worked with it I don't think I would ever buy any.
  10. Whenever you're sizing a panel, you should always work in watts (or kilowatts) instead of amps. This is how you can account for 120V and 240V loads in the same calculation. When figuring tools marked in HP, you can count roughly 800 watts per horsepower; it doesn't matter whether the tool is wired for 120V or 240V. When counting up loads other than tools (lighting, heaters, etc), simply add up the wattage of the bulbs or the value supplied by the manufacturer. You only need to sum the loads which you expect to be on at the same time. In a one man shop that basically means you only need to size the panel for the largest tool plus the dust collector and lighting. Example: 2HP dust collector (1600W) + 3HP table saw (2400W) + 400W fluorescent lights = 4400W simultaneous shop load To figure the minimum size of the panel you need: 4400W / 240V = 18.33 A This example shop would just fit with a 20A panel. It is generally advised to bump up at least 20-25% or to the next standard size so this shop would be just fine with a 30A panel. Unless you're using some pretty intense tools it is extremely unlikely you need a panel larger than 50A in a non-commercial shop. The price of the panel itself isn't that much greater to go to something like 100A, but the cost of wire can be pretty significant.
  11. Your jointer should be fine for pieces that length. I find it helpful to use an actual ripping blade when working with hard maple to reduce burning. The 40 tooth you bought is really on the high end in my opinion for rip cuts, although it's ideal for cross cuts. I use a 24 tooth blade like this one: http://www.amazon.co.../ref=pd_cp_hi_3 to rip maple. Other species you can get away with a 40 tooth combo for rips and crosscuts, but maple burns so easily.
  12. I would probably go with hard maple, just based on my experience digging around at the lumber dealer. I've always been able to find better looking clear boards in hard maple than in soft which is often more streaky and may have some more imperfections. As far as the performance of the cutting board surface I don't think it would really make much difference.
  13. You can make an estimate by taking the power consumed by the tool in kW (1HP is approximately equal to 0.75kW for tools labeled in HP) and multiplying it by the number of hours per month you expect it to run. Make these estimates for all your tools and add them up. Make sure to consider your heating and cooling systems if those are electric, your light fixtures, and add a little for overhead. Example: 2 HP dust collector running four 40 hour weeks. 2HP * 0.75 * 40 * 4 = 240 kwH of energy consumed by the dust collector over four 40 hour work weeks. Example: Twenty 32W fluorescent light fixtures running 10 hours per day every day. 20 * 0.032 * 10 * 30 = 192 kWh energy consumed per month BTW, residential usage estimates vary a lot based on what area of the world you are from and what type of fuel is used for central heating and water heating. Most of our energy at home is used heating and cooling, so depending on whether your water heater, stove and HVAC uses electricity or gas greatly changes the typical monthly electricity use.
  14. Just an FYI post: That is an older style of dryer receptacle officially called a NEMA 10-30R. These were used from WW2 up until the 1996 electrical code when they were replaced with the safer four-prong 14-30R receptacles. The same thing happened with electric ranges, just the 50A version 10-50R to 14-50R. The three wire versions were introduced during WWII to conserve metal by using the three wire cables instead of four, with the understanding they were somewhat less safe but the metal was needed elsewhere. Due to lower installation cost for builders, they managed to keep the code exception around until 1996. The safety issue in question is that in the 10-30 configuration the ground and neutral share the same wire and the same prong in the cord which means that metal chassis of the appliance is bonded to the neutral conductor, which like the hots, carries current. If/when the neutral wire gets loose, corroded, cut, etc and either of the hot wires remains intact then you will now have a floating potential on the appliance chassis of up to 120V with respect to earth. This means that you can touch the dryer with one hand and the properly grounded washer or plumbing right next to it and get a serious shock. The newer 14-30 circuits have separate ground and neutral conductors and require that the neutral conductor is isolated from the appliance chassis making it much safer in the event the cable or plug becomes partially damaged. You may think it's rare for only the neutral conductor to burn loose, but I have seen dozens of this exact situation so it really does happen in real life. The issue is the 10-30 devices are now listed as "replacement only" so it can only legally be sold as an exact replacement of an existing part. There's a good chance their suppliers don't even produce the 10-30 cord caps anymore. The prefab 10-30 cord sets are used to install new dryers in pre-1996 homes, but other than that there's no legal use for a 10-30. With all that said, this is not as big an issue for 240V power tools as it is for ranges and dryers because power tools typically only have one 240V motor and no 120V components which would introduce a current on the neutral. The hazard in dryers and ranges exists because those appliances have a mixture of 240V (heating element) and 120V (drum motor) loads powered from the same cord.