Electrical Breaker and dust collector question

Why not compromise and replace the breaker with the "slo-blo" variety? They are built to accept temporary surges without going all crazy. One variety is "High Magnetic Circuit Breaker" which will withstand temporary loads of up to 20x its rated capacity. Here's one:

Leon wrote: ...

It has a time delay.

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It may not be dangerous at all. The wire ampacity is based on the temperature rise in the wire at a given current level and the maximum temperature the insulation can withstand without damage. It could be that for brief periods of usage and enough down time to allow the wires to cool, you'd never exceed the temperature limits of the wiring. But that's a pretty big if.

If you decide to go that way, and the danger isn't trivial, when the fire department completes its investigation and finds a 30amp breaker feeding 12 ga wire, expect the company that wrote your homeowners insurance to refuse to pay the claim.

Incidentally, if the circuit is properly sized for the full load amperage of the motors on the circuit, the starting inrush will not trip a properly functioning breaker. You don't need to size the breakers for the inrush, only the full load running amperage. If you want to size for inrush, look at the motor dataplate and multiply the amperage shown by about 5. Your 13 amp DC would need a breaker that supported over 60 amps.

Tom Veatch Wichita, KS USA

Yeah, about a second or two. I was wondering how they implement it.

You need a higher amp circuit, or plug DC and tabesaw into different circuits, or switch to 220v. My lights used to momentarily dim as I powered on the DC, but switching from 110v to 220v solved that. Plus, there are other benefits to 220v.

Well, you guys put the fear of God (and the insurance company) in me. No 30 Amp breaker. I will look for the "slo-blo" though. What I don't get is how this product ever works, at least with table saws. I think I have a prettty standard setup for the market they are trying to reach.

I'll see how the breaker change goes...

-Jim

The problem is not the current needed to trip the 30 amp breaker. If the current is there it will trip the breaker.

The problem is the 29 amps that don't trip the 30 amp breaker. That is where the excess heat comes from to start the fire.

Dave

Most likely a count down circuit of some sort. When the first motor starts so does the timer. When the first motor is up to speed the count down reaches zero and fires the second motor start.

Dave

Jim;

You shouldn't fear the god of electricity or even insurance. Just have an extremely healthy respect for both.

Dave

I agree.

dpb actually suggested a 30A breaker with appropriate #10 wire, but a

A good solution is 2 circuits using a relay/contactor as suggested by Bob Haller and dpb. The contactor coil connects to the Woodcraft control. The contactor contacts are in the second circuit that powers the DC. You could connect a time delay relay between the Woodcraft control and the contactor so the DC would start a little later. A time delay relay and contactor could also be connected to start the DC on the same circuit after a short delay. It may be possible to add a time delay relay to the Woodcraft control.

All circuit breakers that are used in a house have a time delay trip on overload.

If motors are hardwired, a breaker may be larger than the wire size, but it has to be designed properly.

The product is designed for relatively low amperage devices, a sander and a shopvac for example. It's not meant to be used with two 1.5 HP motors.

old wive's tale. you may have trouble getting another policy, especially once you get into the national insurance database, but there's nothing in current policies that states this.

It seem the OP's switch should have had this feature to start with.

Breakers are designed with different trip curves depending on the application.

Breakers designed for resistive loads will trip sooner than one designed to handle motor inrush current. Each manufacturer typically has three or four motor curves.

Find a local electrical supply and get a breaker rated for HVAC service.