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So, I rent an apartment and I am allowed to use the basement for woodworking. Problem is, the outlet that I use to power my tools (table saw and planar) is supplied by an occupancy sensor switch that also powers the lights in the basement. This sensor switch is a Lutron Occupancy Sensor Switch which has a ballast rated for only 2 Amps. I found this out after it blew and I took the box apart to investigate. (Model number: MS-OPS2H-WH)

Now, I am looking to purchase a similar occupancy switch but want to make sure it will be safe, will not burn the place down, and not keep blowing each time I turn the switch to my table saw on. This basement only has two working outlets (now down to one) and the other outlet is already at capacity supplying a dryer and a humidifier.

I need assistance in finding one that can replace the current one while using the same wiring box and support a few LED lights and permit power to a table saw without blowing.

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    I'm a bit confused - woodworking equipment should be connected to a suitable switch/relay/contactor, not to a dimmer or ballast. A quick search here found some switches that are rated for 15 A - can you investigate them and determine if they work for your needs?
    – nanofarad
    Nov 20 '21 at 2:57
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    I don't think you can run power tools on an occupancy switch. You are going to need to figure something else out. Probably talk to an electrician. Or convince the landlord to replace the occupancy switch with a normal switch rated for 20 A.
    – mkeith
    Nov 20 '21 at 3:30
  • There are battery powered tablesaws but they are expensive.
    – mkeith
    Nov 20 '21 at 3:31
  • Thank you all for the responses. So, I cant explain the the "whys" as to the basements wiring. The house is over 100 years old, built in 1918, and the wiring is and such was DIY by the homeowner. My number one concern is safety from electrocution and fires. I will talk this over with him and see what we can work out. The house receives 300 amps from the street, then that is divided amongst four fuse panels. The homeowner panel powers the basement and various lights and common area baseboard heaters. I will show him both the Leviton sensors and ask him about installing a separate outlet.
    – J Alex
    Nov 20 '21 at 5:51
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You can't do woodworking there. You don't have any power.

The problem is, either someone hung a convenience receptacle off a lighting circuit. Or, the shop uses "plug-in" lighting with receptacles on the ceiling, which is quite common in shops, and perhaps you didn't realize that's not for tools.

If we were in the UK with their 6 amp lighting circuits, this would be a non-starter. As it happens the US specifies 15A lighting circuits, and so it's possible to run smaller power tools on a lighting circuit. It is not possible to do it off switches intended for lighting, however. They are not made to hold up to power tool demands.

Indeed, the "ballast rating" of 2A corresponds closest to the motor load (since the inductive kick of both of them is the limiting factor)... so we're talking 1/4 horsepower at the absolute outside. Can opener. Tops.

Face the music. Add a circuit.

So, to develop that into a usable shop, you will either need to find power outlets actually intended for non-lighting, or have a circuit added. It sounds like the power is perfectly modern at least up to the metering, so I presume there is a competent panel in there somewhere.

This is straightforward work for an electrician, especially if it's typical "shop space" with open walls.

Neither you nor the landlord can do electrical here

Generally, only owner-occupants can do DIY electrical. That is allowed because no one will suffer from your mistakes but you. It's not allowed in multiple occupancy buildings, nor by landlords, nor by tenants. In those cases, only a licensed electrician can do the work.

You can talk to the permitting authority (AHJ), but sometimes they will allow trivial work (socket repair) or doing some "apprentice tier" work like installing empty EMT conduit that is easily inspected.

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If this helps you understand what the electrician should know, he will best advise how to be compliant to safety and how to test the resistance of the existing outlets and what loads are being shared to consult the owner.

But you cannot have a table saw on a 2A occupancy outlet.

Dimmer switches must be derated 50% connected to heavy motor loads because of the 300% to 500% surge currents and reactive load power factor (p.f.) which means the reactive inductance for stored energy and current adds to the real current which does the work and raises the conduction losses in dimmers and contacts.

The age of the wiring and distance from the service panel must be examined.

The goal for safe wiring is to minimize the voltage drop from the service panel. 5% is tolerable. 10% might be a concern and more unacceptable.

If it had AWG16 wire for 15A breaker service then the voltage drop from 0.8 ohms per pair of 100 ft (AWG16) means 0.8V per Amp per 100 ft. assuming perfect unoxidized connections V = I x R = 1A*0.8 ohms=0.8V

Now let's say table saw is rated at max load for 12A which in load is 120V/12A= 10 Ohms but might actually draw 300% to 500% times this current at startup. This means the motor wire resistance is the initial load until it spins up meaning the load might be 10 ohms / 500% or 2 Ohms. So if 100 ft AWG is 0.8 Ohms and motor shows 2 Ohms at start then the voltage has dropped 2/(2+0.8)*100%= 71.4% or a drop of 29% of the line voltage with 5x 12A or 60A start surge. This means if you had a Triac rated for 60A, it would survive a rapid start even if the breaker tripped. It might be sharing other loads like the baseboard heaters, which is a problem. But if a 30A Triac was used you would have to start it < 50% until it reaches a steady speed and increase it slowly to full ON over a 5 second period. But most dimmers are rated for only 15A so you would have to start around 25% and take twice as long at which point the Triac will be running at maximum heat and that reduces lifespan but it might work if started at 25% then slowly increased over a longer time. But started at a low voltage where the motor doesn't turn means the motor is heating up without forced air cooling and that's bad for the motor.

This story tells you 100ft of AWG is far too long with 29% voltage drop at start with 120V but if it were 5% then 100'/6 = 16 ft might work.

Going down 3 gauges cuts the resistance in half (50%), and going down 4 AWG numbers from 16 to 12 is about 40% of the resistance which also drives up the cost of the wire.

That's my EE engineering perspective. The highest resistance of the old breaker, screw terminals , wire , outlet connections divide by the path length in mm or feet determines the temperature rise to dissipate power loss and create any concerns above 85'C. So weak screw terminal connections that are oxided from not being air-tight in the 1st place is where I would check from end-to-end with a load test for voltage drop across the screws with a DMM if there was more than a few % Voltage drop at say 10 Amps

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