Automatic Line Interrupter

Jul 30, 2007 5 Replies

I would like to make a line interupter that monitors the incoming 240 V AC line and turns off a 30 Amp Dryer, 50 A Stove, 20 Amp Refrigrator and



20 Amp washer line. The Dryer and Stove are 240 V lines and the washing machine and refrigerator are 120 V lines. I would like the unit to stay off if the power goes off and once it goes back have a 5 minute delay. This will protect the LCD Panels on these devices. I have been looking at a Time Mark Product and solid state relays. However, the Time Mark
240-160BR is not available and has no automatic resets. Any thoughts or comments ?

Thank You,



Howard Epstein


I do my motion lights with a 4060 CMOS, a 2n2222 and an SSR. A few resistors and capacitors are you are done. A little more and you can monitor trips and switch remotely.

One way would be to have the loads you described fed from a sub-panel of their own, and in turn feed that sub-panel with a 2-pole contactor. Have the coil of the contactor energize through the Time-Mark device, and a TDOE timer set for 5 minutes.

Sounds like you want a generator transfer switch. check out a company called Asco.

Probably not, as least not as well as you would like.

I hate to sound negative but likely a surge will short out the solid state relay.

I use surge arrestors at problem locations. these are fairly expensive, $500 to $1,000 or more for 200 amp 3 phase service. They are not 100% effective but they do reduce storm related damage considerably.

The Time Mark Device which provides the voltage monitoring of the line and a relay contact set is not available any more. I can build a time delay of 5 minutes using a 555 Timer Circuit and I know of an Integrated Circuit that will monitor the line. However because of liability I prefer to buy a commercially produced UL approved product. I know the time delay is available but not a 240 Volt line monitor with an output. That is the crust of my problem.

Howard Epstein

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