Tricks of the Trade?

[ote]

I remember an elderly owner of a company I used to work for doing a troubleshooting call at an older church. They had a short circuit on a receptacle circuit in the sanctuary with an older fuse panel. I was as green as could be at the time, and remember him replacing the blown edison based fuse with a medium based light bulb to try to find where the short was at. I never did understand the purpose of that, and really haven't since tried to figure it out other than to put some resistance in the circuit to ease troubleshooting with the power on. Wondering if anyone could explain that and if anyone knew of other "tricks of the trade" that some of us could use................This came upon me after reading the post "lighting circuit power" by BJ Conner

 

[SOG38]

I have used this method in many short circuit trouble shooting situations.
The light in place of the fuse would glow brightly with a short situation. You would want to make sure all other loads are disconnected. As the circuit is opened out in the building you would look for the light to go out. When it goes out you have located the area of the short circuit. It works great. Work Safe

 

[LarryFine]

I've done that plenty of times, either with a bulb screwed into a fuseholder or a bulb in a rubber socket wired between the breaker terminal and the wire.

The bulb does double duty as a current limiter and as a visual short-circuit indicator. The bulb burns full with a short, and varies with various circuit loads.

 

[rcwilson]

When chasing shorts in control wiring that ran all over the plant, my electricians ran an extension cord and placed the light outside the electrical building so they could see it from the junction boxes located on the 8 story material handling structures.

 

[dbuckley]

Its a very old trick.

Of course, you need to treat the wiring with respect as it's hot, and although the bulb does limit the current, its not enough of a limit to save your life if it all goes wrong...