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Old 04-13-2007, 10:13 PM   #1
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Technical questions about a remodel for a woodshop

Setting up a woodworking shop

I have been working in the custom cabinetry trade for the past 18 years and I'm looking to switch professions. I believe I know what are typically considered the "basics", but my current situation is a bit more involved and requires responses from someone who knows their stuff, especially when it comes to making relay switches work with my machinery/dust collector.

My wife and I just purchased a new home, about 3,500 sq ft that we are moving into next month. The bozo homeowner decided that he was going to run the electircal wiring for the pool table light using "lamp cord" To make things worse, he ran all of the plug in outlets in the basement using extension cord. Needless to say, that all needs to be fixed. That part I can handle.

Here is the deal:

We currently have 200 amp service with a sub-panel and there are only a total of 2 spots left. Because of some of my woodworking machinery being 220, that takes up two slots right there and I need a minimum of 6 open slots. I will be running condiuit from the existing panel, across the basement and to the garage to another sub-panel. which is where I will have the breakers for the garage/shop. Connected to this will be at least 1 relay switch so when I kick on let say my table saw, the dust collector will kick on at the same time. Both my table saw and dust collector require 220. I want to also add a disconnect switch at my table saw too. How do I determine which relay switch and what brand to go with, along with learning how to wire it? We are going to hire an electriction to change out the panel from 200 to 400 amp. Any ballpark figures of what to expect for just changing out the panel and marking the existing electrical properly? In the garage, I will also be adding 8 foot magnetic ballast shop lights too. I know there is a rule of thumb to go by in regard to how many lights you can add to either a 15 or 20 amp breaker. With this, I'm searching for an explosion proof motor/fan and explosion proof lights to go into a spray booth that I will be making. I had a commerical grade spray booth in he past, but considering that I'm now doing this as a hobby and it's out of my home, I don't see a point in spending the money on that. My total work space will be about 30'x33'. A 3 car garage and almost tandem deep.

With all of the different machinery I have, what suggestions do you all have as a first step to this process? There is already conduit running to the garage, but it's for regular outlets. Should I run a 1" pipe from the new box out to the garage so I can run more wires in one shot or do say two 3/4" pipes? I have a pretty decent distance to go from the panel to the garage, so would you recommend 10 gauge wire from one panel to the next?

Thank you ahead of time



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Old 04-14-2007, 05:17 AM   #2
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I may be a bit confused by your layout. I am understanding that you will be replacing the existing service with a 400 amp. You then will be running wires to a new sub panel in the garage/shop which is where the wood working machinery and paint booth will be located.

I did not catch if the shop will be attached to the home, or in a detached building. We also need to know just how far, "a pretty decent distance" is. We will need a number to plug in for voltage drop calculations. This will be wire run as the wire flies not as the crow flies.

I am also guessing that you are confusing Ideas when you mention the number 10 wire to feed the shop. The shop sub panel will be feed using large wires, and then the smaller wires to the equipment will go from there.

I choose to stay out of the estemating part. It will depend on the market in your area. Get three to four bids and throw out the lowest and the highest.

Regarding ballasts. I looked at the advance web site and an 8 foot t 12 two tube ballast is about 1.7 amps each. You can load this lighting circuit to 80 percent. So 16 amps max on a 20 amp circuit.

Regarding conduit and wire size. The feeder to the shop will have to be in one conduit. You cannot run each of the feeder cables in a seperate condit. For conduits for branch circuits you want to try to plan for no more than 3 circuits in any one conduit for circuits up to 30 amps. After that other de-rating factors get in the way. For larger loads, try to put them each in thier own conduit.

To start your planning process you need to determine how much load you will need at your shop. Write a list of the amperage and voltage of all the equipment you plan to use. Convert this number to wattage so that you can add equipments of different voltages easily. W=I x E or Watts = amps x volts.

Once you have the list of equipment, including lights and general purpose recepticles, we can do a demand load calculation to determine the size feeder you need for your sub panel, and discuss conduit options. I also reccomend that you put a fudge factor in for future expansioin.

If this is a one man shop, you may be able to treat some things as
Noncoincident Loads, meaning that since you cannot use the table saw at the same time you run the plainer, you only need to calculate the largest load in your total.

Regarding the dust collector. It would be easy to build a small control cabinet and run interlock wiring from the starter of the other equipments to the starter of the dust collector. A couple 120 v ice cube relays and an HOA (hand off auto) switch and you will be good to go.


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Old 04-14-2007, 09:23 AM   #3
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I would have go guess that from the existing panel to the new panel is probably no more than 40 or 50 feet. As mentioned, we haven't closed on the home until next month.

Because this was a model home and the homeowner never took out the realtors office "which takes up part of the 3 car garage" there is already electrical plug in outlets in there. I would say that I'll have about 15-20 regular outlets. The lighting for the shop are "eyeball lights" like you'd see over a fireplace. The guy who we are buying the home from didn't have all of his marbles. There are probably 7 of these. The 3 car garage is connected to the home.

When you say feeder tube, do you mean probably 1" pipe that would come out of the new panel?

What I would like to do is run the "feeder tube", attach the new panel, relay switches, outlets throughout the garage, lights, run the wires within the garage, but leave the major panel change and running those wires to the new box for the professional.

For the shop panel, would you recommend a 100 amp panel and what manufacturers do you prefer. I will probably have no more than 10- 8' ballasts for the lights.

I'm not sure how many 15/20 amp breakers I'll need, but I know for a fact I'll need at least 6-8 with room to grow to maybe 10 slots for just my 220 line equipment. I believe 3 pieces of my equipment require a dedicated 20 amp breaker for each. So if I'm at the new panel in the garage, what gauge wire should I run from the 15/20 amp breakers and what gauge for the 220 lines? Also, would you run 1/2" conduit or 3/4" around the shop?

To give you an idea about the machinery:
Powermatic table saw 3hp 220 volts, recommends 10 gauge wire, currently on a 30 amp dedicated breaker, 3/4 hp 1 ph

One dust collector- plugs into a regular 115 volt outlet, but requires a dedicated circult, 1.5 hp, dedicated 20 amp breaker

Wood Lathe- Plugs into a regular 115 volt outlet

Main dust collector- is 2hp motor 1 ph. 230 V only

Spindle Sander- Plugs into regular 115 outlet 110 V 1/2 hp 1ph

18" Band saw- plugs into regular outlet 1.5 hp 1 ph 115 V

Air filtration unit which mounts at the ceiling- Plugs into regular outlet 1/3 hp 115 V This will typically be running all the time.

Surface sander 1.75 hp 1 ph 115 V. It also says Motor "TEFC", what does that mean?

Bench top mortising Machine- Plugs into regular outlet 1/2 hp 1 ph 115V

At this point, I don't know what the motor for the spray booth will be, nor the explosion proof lights for it.

I will be adding a few drop down extension cords too. The 3 machines that will likely run at the same time are the 220 V dust collector, the 220 Table Saw and the 220 Ingersol Rand 60 Gal 5hp Compressor "which the compressor requires a dedicated 220 line also.

I looked in the manuals for each of these and this looks like the best knowledge I'm able to provide to you. I don't see anything about watts, so hopefully you can figure it out from what you see. and please type out how you figured this all out so I can see how it's done, vs just a final number or information.

Thanks for your help.


P.s. You said......
Regarding the dust collector. It would be easy to build a small control cabinet and run interlock wiring from the starter of the other equipments to the starter of the dust collector. A couple 120 v ice cube relays and an HOA (hand off auto) switch and you will be good to go.

What does 120 V Ice Cube Relay mean and hand off auto? With the HOA do you mean a disconnect switch at say the table saw? Yes, I'm a one person deal
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Old 04-14-2007, 11:44 AM   #4
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Given the distance, voltage drop should not be a problem. We can probably ignor that for future posts.

Existng recepticle and lighting circuits can remain if you like, this will save you a bunch on the future wiring costs. For additional lights you may want to add circuits to the new panel.

I never said anything about any "tube" What I said was conduit size. I cannot reccomend a size till after we total the loads.

I have no intention of doing all the math for your and posting the results, unless you are willing to pay me a consulting fee. I will help you figure it out.

You need to do the calculations and post them, so that we can tell you where you went wrong.

Table 430.248 of the NEC gives you the numbers that you need to use for doing calculations of this kind. The results will be in amps and we will need to multiply by volts to get the watts.

Go to this page:

To prevew an online version of the table I just posted so that you can do your calculations. Or write your list.

You need more info on the lathe, and at least an estimate on the future equipment.

I take my work seriously and will not guess at what you need.

Once you can provide a list of All of the equipment in voltage and amps or watts, and total number of general purpose recepticles. Post back. We can continue from there.
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