Electrician's fish tape activator?

[Wagengineer]

When using a conventional electrician's fish tape in a wall, I find that I frequently need to determine where the tape is located. I found non-contact hot circuit detectors are very useful, so I thought it might be feasible to make the fish tape "hot" by applying 120 V AC to it. But, in order to eliminate the possibility of serious shock, it would be driven by a high impedance--something like 120 Kilohms. That would limit the current in human contact to 1 mA, which apparently is quite safe.

Does such a commercial product exist? If not, is anyone interested in developing and marketing it? (Obviously, it needs to go through the UL approval process.) There should be a good market for such a device.

Robert R. Wagner
ExpanTest, Inc.

http://home.gwi.net/expantest/

 

[rempman]

There is fishtape on the market that has a tracer wire included. The idea being you could put a tone on it and trace it with a reciever.

Try FiberTek Tracer tape:

http://www.fibertekinc.com/pull_details.cfm?ID=5

 

[itsmoked]

Wagengineer; Are you sure the "live wire" detectors are not running on the "B" magnetic field? If they are then you would need current not just voltage? I'm not clear on how they work...

I guess if you hook one end of 20 feet of wire to a hot then go check the unconnected end for being live this would show if those detectors are Magnetic or Electric field sensors.

 

[Wagengineer]

rempman:

The FiberTek product suggests using an RF signal: "Simply direct a radio signal on to the TRACERTAPE and follow conventional locating procedures." I'm not sure how many electricians have the means to do this right at hand. That's why I thought of the simpler application of a 60 Hz signal from a high-impedance source.

BTW: I noticed that GFI's are designed to trip at 5 mA, so applying 120 V through a 40 Kilohm resistor (3 mA), should be safe. In the commercial product, one could include a GFI, for an additional measure of safety.

Itsmoked:

No, the live circuit detector is electric field (though magfield detectors are available, too). See, for example,

http://www.electrical-contractor.net/The_Store/EX/DV30.htm

(Mine is a simpler one, purchased at Home Depot.)

Thanks to both for your advice.

Doesn't anyone want to take up this idea and develop a product?



Robert R. Wagner
ExpanTest, Inc.

http://home.gwi.net/expantest/

 

[itsmoked]

Thanks for the M or E clarification.

I don't know if I like the energized tape idea. You can still kill someone many ways with 5mA..

Someones heart can go into some pathologic rythm from a tingle across the chest.

Not to mention the ol BZZZZZZYOW! While standing on a ladder or some other precarious position.

The low voltage signal tone would work just fine They use them to find pipes buried eight feet underground!