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Wiring Scenarios

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8888

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Does anyone have suggestions regarding these wiring scenarios?

I have a mobile work bench with built-in tools and I need to supply power to the work bench for its tools and receptacles.

I plan on using the cable from a 10 gauge extension cord, the first ±20-30 feet of cable will go from a wall receptacle in the garage to a J-Box on the work bench. The remaining cord will be used to wire from the J-Box to other switches and receptacles on the work bench.

*SEE DRAWING
Workbench Electrical.png

Tool Amps:

Highest draw tool = 15a

Dust collection vacuum = 8a

The worst scenario would be a 15a tool plus 8a vacuum (15+8=23a) on together. Since these ratings are most likely ‘startup’ amps, I have the ability to stagger the startup of each tool. Example, start the vacuum and then a few seconds later start a tool.

Garage Circuits Available:

15a shared (unlikely anything would be drawing power (or much power) on this circuit while I’m working at the work bench)

20a dedicated

Q: Add a 20a style plug to the cord and wire the entire work bench with 20a receptacles and switches. I lose the ability to ever plug the work bench into a 15a circuit, unless I use a 20 to 15 adapter when needed, which I guess is available.

Q: Leave the factory 15a style plug on the cord and wire the entire work bench with 20a receptacles and switches.

Q: I looked at some 20a Legrand products at Lowes. Both the receptacle and switch stated 10-14 stranded or solid. Both had the side clamp feature that I need.

The switch’s clamp was out in the open with plenty of room to get a 10g stranded in, but on the receptacle the 10g stranded needed to pass through a hole first to get to the clamp. That hole IMO didn’t allow the 10g stranded to pass easily. You had to twist and push hard to get it in which really mangled the outer strands.

I haven’t yet been to Home Depot to see what Leviton offers.

Q: Per the drawing I would like to have 2 locations to switch the vacuum on/off. Would there be a problem if switch #1 was ON while switch #2 was also turned ON by accident? In other words the vacuum receptacle would be receiving incoming power from both switches.

I’m not looking for a 3-way wiring option, as that would cause one switch to be in the UP position and the other to be DOWN, I want UP to mean ON, and DOWN to mean OFF for both switches.

I will wait for comments if anything needs clarification.
 

Snoonyb

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You mite want to think this through.

Two pieces of equip. drawing 23amps under load, on a 20A circuit?

Having both switches on for the vac. won't work, but suppose it would and you had a fire in the vac., so you'd have to run around the table.

Why not a 3way?
 

pjones

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Go with the dedicated 20 amp circuit and use an adaptor if you ever need to plug into a 15 amp receptacle. Do you have an option to go with two separate 20 amp circuits so you have more amperage to play with? You are pushing your limits trying to run 23 amps through it. Typical rule of thumb is to load up your breakers to no more than 80% of its rated capacity otherwise you may get nuisance trips.

The 23 total amps that the nameplates show are the actual amps that you will see when the tools are under load. The startup amperage is actually 6 times the shown rated load of the motor but is only momentary so it doesn't trip the breakers because they are designed with that in mind. You will probably still trip the breaker if you are trying to run 23 amps through a 20 amp circuit for much duration.

Having two switches to turn on the exhaust fan won't hurt it providing that the power supply from each of those circuits are both from the same phase of power. If they pull off of two separate phases then you will supply a much higher voltage if they both get turned on at the same time (usually 208 or 240 volt). Something to consider with this method is if someone goes to fix it and they are unaware that there are two power source then it could (although unlikely in your scenario) create a hazard . Keep in mind if it is not a 3 way switch then that makes it less convenient to use since when you use one you are married to it, meaning that you have to return to that specific switch to turn it off and if both switches get turned on then both need to be turned off before the exhaust fan will stop. I'm not sure if that is an issue to you but if you are moving around the bench much while you work then it could get annoying. Have you considered mounting the switches wired for 3 way control but with a horizontal throw instead of vertical? It would alter the "up is on" visual so it's not as confusing. Not that you have to but something to consider if you haven't already.
 

pjones

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What kind of equipment are you operating off this table? Is it single phase or three phase power? It didn't change my reply much, mostly just curiosity.

If you don't have room for two 20 amp circuits then what about running one 20amp that you mentioned and utilizing the 15 amp circuit that you talked about also. I really think you will be disappointed if you try to use one single 20 amp breaker and would save yourself a lot of grief if you can get more ampacity to work with.

You would need to have two cords that plug into each circuit but it would mean being able to finish the project without resetting the breaker a bunch of times until you get fed up with doing that and ultimately decide to complete your project without the exhaust fan running.
 

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