Another post on the humble contactless tester

[Jupiter01]

I own a Fluke voltage stick (and a 2 pole tester I should add). I often hear that the voltage stick is unreliable. I appreciate that and as I stated above, I also own a 2 pole tester for proving dead before working on electrics.

However, I have a specific question on the voltage stick please. If I have it pointing to a circuit and it is beeping, I then switch off the associated breaker and it stops beeping. I then repeat this process a couple of times to prove that I have the correct breaker and that it starts and stops and electricity based on the position of the breaker, can I rely on the voltage stick?

When and how could this be unreliable?

looking forward to your responses.

 

[CBW]

I’ve had voltage pens/sticks pick up on static charges, so when near a rubble sack that has a charge

I also own a voltstick branded LV50, which has on occasion lit up a boiler case, only to find out it’s dead

 

[Jupiter01]

I’ve had voltage pens/sticks pick up on static charges, so when near a rubble sack that has a charge

I also own a voltstick branded LV50, which has on occasion lit up a boiler case, only to find out it’s dead

But would you expect this to detect and undetect power as the breaker is flicked?

 

[sparkwright]

Jupiter, generally, it's good for identifying an unknown cable in the manner you describe in your second paragraph.

However, when they don't work properly, they can light up if when the actual cable is isolated by removing the fuse or circuit breaker, then it stops lighting when the main switch is isolated.

And other similar scenarios.

 

[plugwash]

When and how could this be unreliable?

It could be unreliable if the circuit under test is already isolated but has capacitive coupling to a circuit that you are toggling. I think it's pretty unlikely in practice though.

And of course there is the possibilty of a relay on one circuit controlling equipment on another, though that would equally affect any tester.

 

[Taylortwocities]

I would (often) use a Voltstick in the way that you describe, as a belt and braces cable live indicator
BUT
I will always carry out correct safe isolation procedures (on whatever it is) before working on it and putting my fingers on unknown wires.

 

[Jupiter01]

I would (often) use a Voltstick in the way that you describe, as a belt and braces cable live indicator
BUT
I will always carry out correct safe isolation procedures (on whatever it is) before working on it and putting my fingers on unknown wires.

If @Taylortwocities does what I do, it must be worth doing! Sounds as though I am using the stick in the right way.

 

[CBW]

If @Taylortwocities does what I do, it must be worth doing! Sounds as though I am using the stick in the right way.

Kissass

 

[ericmark]

I have only once worked on an IT system, a tunnel boring machine in Hong Kong, since no earth reference point we all carried neon or no contact testers to ensure safe to touch anything, what we were testing was if the item was a different voltage to ourselves, bird on the power wire idea.

The problem with the no contact tester is where it gets its reference from.

These are all contract less detectors and all very different, they detect electric and magnetic fields with varying degrees of distance and reliability. I had a combined magnetic and voltage detector used in the main to test solenoids, it was not cheap when compared to simple volt stick, and I found it very helpful, but it was an indication only, and one needs to understand it's limitations.

So before removing a switch from the wall it is possible a detector may show if live or not before removing the screws, but once screws are removed you want a more reliable test, even the neon screwdriver is better than contract less testing.

 

[opps]

I have only once worked on an IT system, a tunnel boring machine in Hong Kong, since no earth reference point we all carried neon or no contact testers to ensure safe to touch anything, what we were testing was if the item was a different voltage to ourselves, bird on the power wire idea.

The problem with the no contact tester is where it gets its reference from.

These are all contract less detectors View attachment 266729 View attachment 266730 View attachment 266731 View attachment 266732 and all very different, they detect electric and magnetic fields with varying degrees of distance and reliability. I had a combined magnetic and voltage detector used in the main to test solenoids, it was not cheap when compared to simple volt stick, and I found it very helpful, but it was an indication only, and one needs to understand it's limitations.

So before removing a switch from the wall it is possible a detector View attachment 266735 View attachment 266737 may show if live or not before removing the screws, but once screws are removed you want a more reliable test, even the neon screwdriver View attachment 266738 is better than contract less testing.

I have a contactless neon screwdriver that lives in my pocket. My only complaint is that the LED is difficult to see in bright sun light.

/ducksForCover