What is a Film Disc Cutout anyways?
A film Cutout, sometime called an "antifuse", can be thought of as a backward acting fuse. It blows on over voltage, not over current and when it blows it shorts, not opens like a regular fuse.
How is it used?
A film cutout is used in series lighting. For example, imagine an airport runway. This runway is 2 miles long and there are lights spaced 100 feet apart. This is over 100 lights on one side of the runway. Now remember there must be lights on both sides, the ends, usually down the middle, side markers, taxiways, etc. If you tried to run parallel lighting (like in your house with 2 wires going to each light) the wires would have to be huge since there would be such a voltage drop over this distance. Series lighting does not have this problem. It uses a high voltage but the current is the same because it is a series circuit.
So, what's the down side?
Are you old enough to remember the old style Christmas tree lights? This was series lighting. If one bulb went out, they all went out. All you could do is change bulbs one at a time until you found the blown bulb.
Enter the Film Cutout!
The film cutout eliminates this problem by being placed in parallel with the light bulb. Lets say the light bulb runs at 30 volts and the Film Cutout is designed to blow at 100 volts. Normally the cutout just sits there doing nothing until the bulb blows. When this happens, the voltage rapidly rises due to the lack of current flow. The cutout detects this high voltage and shorts leaving the rest of the lights burning. A technician changes the bulb and cutout at the same time.
How Expensive are they?
MSRP is $370 per bottle of 100.
Does one size fit all?
Not really. Film cutouts come in four different breakover voltages ranging from 30 Volts to 390 Volts. Your lamps and configuration will determine which type you need.
Green Dot - Breakover from 30V - 80V: This is a direct replacement for General Electric part number 4815920-G20 (35-440647-04) * This Green Dot also crosses to a Crouse Hinds Part Number 10047-409.
Blue Dot - Breakover from 50V - 130V: This is a direct replacement for General Electric part number 4815920-G2 (35-440647-02) *
Black Dot - Breakover from 100V - 250V: This is a direct replacement for General Electric part number 4815920-G1 (35-440647-01) *
Red Dot - Breakover from 250V - 390V: This is a direct replacement for General Electric part number 4815920-G3 (35-440647-03) *
* = Please note these cutouts are manufactured in the U.S.A. by www.filmcutouts.com and is in no way associated with General Electric Company or any of its affillates. These numbers are for cross reference only.