STATUE
Active member
Should a bog standard tester achieve continuity, obviously connecting together two wires at the top and then testing at the bottom - 30 foot mast ?
MAST CONTINUITY TEST
- Thread starter STATUE
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wonkywinch
Well-known member
No problem at all. You might just start measuring cable resistance depending on the gauge of the cable.
VicS
Well-known member
Or use the table here AWG - American Wire Gauge Current Ratings and interpolate between the values given
It will , or should,
be lower than can be measured accurately with an ordinary multimeter
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William_H
Well-known member
To me a strange request. If it has a wooden mast then yes check continuity of any connections for lightning protection or light negative returns. If an aluminium mast then no real concern. If he is asking about continuity of stainless steel or steel rigging wires then poor continuity might indicate corrosion or possible failure.
In any case a standard digital multimeter usually has a low ohms range of 0 to 200 (199) This range becomes a bit unsuitable for resistance around one ohm or so. Indeed as said the resistance of the leads and wire extension become significant to the total resistance. Short the ends of the leads together and read what is residual resistance. Possibly half an ohm. So this should be deducted from test result.
Next problem at these low resistance is to get a decent connection to the mast or wire. Quite difficult.
If Op wants to go ahead checking low resistance. There are all sorts of circuits available to check low resistance. A simple way might be to connect a high power incandescent bulb (headlight) to a 12v battery. Open that circuit and connect the mast etc into the circuit. Any volt drop might indicate resistance.
In my working days I had a small meter which happily measured .006 ohm the limit for earthing of avionics equipment in aircraft. PM me for more details. ol'will
In any case a standard digital multimeter usually has a low ohms range of 0 to 200 (199) This range becomes a bit unsuitable for resistance around one ohm or so. Indeed as said the resistance of the leads and wire extension become significant to the total resistance. Short the ends of the leads together and read what is residual resistance. Possibly half an ohm. So this should be deducted from test result.
Next problem at these low resistance is to get a decent connection to the mast or wire. Quite difficult.
If Op wants to go ahead checking low resistance. There are all sorts of circuits available to check low resistance. A simple way might be to connect a high power incandescent bulb (headlight) to a 12v battery. Open that circuit and connect the mast etc into the circuit. Any volt drop might indicate resistance.
In my working days I had a small meter which happily measured .006 ohm the limit for earthing of avionics equipment in aircraft. PM me for more details. ol'will
wonkywinch
Well-known member
The OP asked about "obviously connecting together two wires at the top" so I don't believe the continuity of the mast or rigging has anything to do with it, simply two wires.
STATUE
Active member
Thanks everyone - good advice from everyone. Thanks,
B27
Well-known member
Assuming we are talking about 12V DC navlight wiring, not RF or instrument:
I find it's helpfull to test with 12V at a realistic current. A voltmeter will sometimes still show volts when the wires are high resistance.
I have a long test lead, 2 core, which plugs into a cig socket for 12V. This has a 12V 21W car brake lamp bulb in series with the + wire.
So if I short out the far end, the bulb lights rather than blowing fuses.
At the far end there is a small 12V LED, which lights to show there is power.
I connect this to the wires at the bottom of the mast.
I then look for 12V at the top of the mast using something like a 1 watt 12V LED bulb. When the bulb is lit, I check the voltages in search of excessive drop.
I could think up enhancements or better ways, but the above got the job done. Investing an hour in making some test leads in advance can save a lot of time at the yard.
The test LEDs want to be bright enough and have enough viewing angle that you can see them from the other end of the mast in sunlight.
I find it's helpfull to test with 12V at a realistic current. A voltmeter will sometimes still show volts when the wires are high resistance.
I have a long test lead, 2 core, which plugs into a cig socket for 12V. This has a 12V 21W car brake lamp bulb in series with the + wire.
So if I short out the far end, the bulb lights rather than blowing fuses.
At the far end there is a small 12V LED, which lights to show there is power.
I connect this to the wires at the bottom of the mast.
I then look for 12V at the top of the mast using something like a 1 watt 12V LED bulb. When the bulb is lit, I check the voltages in search of excessive drop.
I could think up enhancements or better ways, but the above got the job done. Investing an hour in making some test leads in advance can save a lot of time at the yard.
The test LEDs want to be bright enough and have enough viewing angle that you can see them from the other end of the mast in sunlight.
Alex_Blackwood
Well-known member
If I only want to see if the wires are continuous I.E. Continuity then join at the top, or the bottom and stick a multimeter on the other end. Changing the Ohms scale on the meter will give an idea of resistance, if you want it! I don't think the OP is going to be trying to get too technical.