Editing Building a new shop (section)
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==Electrical== Rule #1: The supply MUST meet the demand with a safety factor of at least 40%. Start with a 100 amp service. 'Demand' fits in two categories; DEDICATED circuits and CONVENIENCE circuits. Lighting, compressors, welders, post hoists, ventilation fans & heating units, reel-trouble lights, refrigerators, etc., are DEDICATED. Bench and wall receptacles are CONVENIENCE, because you're never going to use them all at once. Sit down with a clean sheet of paper and document the electrical tools that normally don't move and consider each circuit and amperage. Some circuits may be used for two purposes, for example, I doubt if anyone would raise a hoist while using the MIG welder. So, that can be the same circuit. Figure for liberal lighting and NEVER put lights on the same circuits as your receptacles. If you trip a breaker (or GFCI) you won't be groping around in the dark. Add the number of circuits and note the circuit's ampacity. Total your amps and multiply by TWO (because we know you're going to get more)and that's what service you'll need. Service panels come by AMPACITY and NUMBER of SPACES. 230-volt breakers occupy two spaces. A typical Service Panel will have a 100amp main breaker and 24 spaces. You can go up from here if more spaces or more ampacity is required. For CONVENIENCE receptacles, use #12AWG copper wire on 20-amp circuit breakers. 30-amp receptacles are normally dedicated to a stationary tool and rarely used as 'convenience' outlets. Don't forget that indoor and outdoor receptacles in a garage must be protected by GFCI's (either ground fault circuit interrupter breakers or GFCI outlets). If you protect the first of the outlet boxes in a circuit with a GFCI outlet, all the rest of the outlets may be protected too. A compressor or 220V mig will eat up 30 - 40 amps. Two-post hoists and 230volt MIG welders normally require 20-amps. "Brown outs", lack of correct power will fry a motor over time. If that shop of yours is getting a regular workout, maybe you should go with a new 'drop' instead of drawing off the house circuit. Better yet, stay away from using aluminum wire. Use copper because it rarely needs future attention, wire sizes are smaller for the same amperage, and it has a far better voltage drop over long runs. Electrical supply stores have copper wire in all sizes if your local 'box' store doesn't have it. Motion detectors work great and are a deterrent to crooks. Point one at or above your entrance door (I also have one inside my garage for when the wife pulls the car in). This is particularly useful in winter months when days are short and weather is cold. BTW, if you live up north, stay away from fluorescent or any lights that use ballasts because if they start, they take a while to put out decent light. Use lighting fixtures that take regular light bulbs with standard 'medium' bases. Fluorescent lighting is fine in heated areas. Consider running all your wires in metal conduit, surface mounted on the interior walls. If you get your shop all wired up and the wires are buried in the walls, it will be inconvenient to change anything later. If you don't like the look of exposed pipe, notch your studs and use thinwall (EMT) conduit. I keep my shop fireproof by using plasterboard (gypsum). It's cheap, clean, warm, durable and easy to repair. Oh, and a torch will not go through it. Bending thinwall is simple with practice. Have an electrician show you how the bender works because there's a lot more than meets the eye. Electricity is very dangerous, and should be handled by qualified Journeyman Electricians. They adhere to the National Electrical Code book, written by the National Fire Protection Agency. You want this level of training and you want their work inspected for insurance purposes. Most cities offer 'Homeowner's Electrical Permits' at a reduced cost. It's perfectly ok to do this work yourself; just hire qualified help. Most inspectors are eager to work with homeowners if they get permits BEFORE work starts. They gladly answer your questions and give sound direction. When an inspector finds "bootleg" work, that's when they get upset, and naturally so.
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