Intermittent short

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  #1  
Old 01-16-17, 08:05 PM
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Question Intermittent short

A fuse keeps blowing in my house, so I tested the fuse socket in my fuse box and found 60 ohms of resistance (which doesn't indicate short to me). I then went around and took out lights and outlets seeing if the resistance changed but it didn't. When I put it back together the fuse didn't blow so I thought hey must have jiggled something right. But a few hours later the fuse blew again.

When the fuse blows its not instantaneous, there is a delay somewhere between a few seconds and a few hours. What can cause this? (FYI the house is old).
 

Last edited by Simon Bernick; 01-16-17 at 08:36 PM.
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Old 01-16-17, 08:28 PM
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Could be a loose wire connection at any junction box or outlet or light socket.
 
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Old 01-16-17, 08:43 PM
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What size fuse? Fast blow or slow blow?
 
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Old 01-16-17, 08:48 PM
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What is the load on the circuit?
 
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Old 01-16-17, 08:48 PM
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found 60 ohms of resistance (which doesn't indicate short to me).
It's not a short but it's pretty close.

You should find what that 60 ohm load is so you can remove it.
Do you have any idea what is on that circuit ?
 
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Old 01-16-17, 08:51 PM
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15 amps, normal house fuse (fast I think).
 
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Old 01-16-17, 08:54 PM
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Theres not much on the circuit, just a few outlets and some lights. Most of the outlets are unused anyway, were talking maybe 500 watts max.
 
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Old 01-16-17, 09:11 PM
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Remove all loads from the circuit. Remove the fuse and screw in an incandescent light bulb. If it glows even a little bit it is time to start opening boxes and pulling out wires. Do not disconnect the wires just separate the wires so they are not touching the box or each other. When the light goes out you have found the short.
fast I think
Better to use slow blow in case there are any motors on the circuit at any time.
 
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Old 01-16-17, 09:26 PM
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Tried the light bulb but it never lit up.
 
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