bernardgreen said:The needle of a small undamped compass ( i.e. the needle is not in a fluid filled compass ) may visibly vibrate when directly over the mains energised heating wire.
Having been in a similar situation with finding communication cables this solution worked locating the cables quite accurately.
It may be adaptable to locate the under floor heating cable
We used a DC power supply to feed a DC current through the screen of the cables and then a magnetic compass to detect the resultant magnetic field.
If the heating cable is a single wire element then with due consideration of resistance and maximum permissable current connecting a suitable battery in place of the mains may create a magnetic field detectable by a magnetic compass.
JohnD said:if the heating is working:
wet-mop the floor and leave it damp. Turn on the heating. You can expect to see the set floor drying out fastest above the hot elements and showing the pattern. You may need to take some photos or mark the floor with pencil or chalk especially in the area where you expect to work.
be aware that floor heating has cold tails from the heating elements to the connector or thermostat which will not be hot but do carry electricity.
applesauce said:Nice idea. But so I'm clear. I need to run a direct current through the cables for this to work and not the AC from the mains.
bernardgreen said:applesauce said:Nice idea. But so I'm clear. I need to run a direct current through the cables for this to work and not the AC from the mains.
Yes a DC supply in place of the mains supply. I will have to think about what you would need as I haven't done it with a heating element before.
What power is the mat in watts ? and How deep below the surface is the mat and how close are the wires in the element. Then need a day to try something.
It is probably not going to work on the temperature sensor cable as they will be a pair ( so cancelling currents and no magentic field ) and it would not take the current needed.
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