Voltage still detected after rcd had tripped? why could this be...

[srl-8]

Hi all,

I have install a RCD fused spur on the end of line feed to a bathroom lighting circuit. Thus protecting the bathroom with rcd.

I tested the rcd (manually via the push 'test' button) and it killed the lights and fan as expected.

I used my volt stick to confirm that the cables were dead, but to my surprise , The voltstick was telling me the there was voltage still present. How could this be?

My understanding was that with the RCD tripped, it should kill all power on the load side of the spur, .

Any ideas????

Thanks

 

[telectrix]

voltstick picking up off incoming side. use a proper tester to confirm. voltsticks are only a rough guide and don't bloody rely on them.

 

[Lucien Nunes]

Use a multimeter/ MFT rather than a voltstick to confirm what voltage is where. Voltsticks are useful but only give an indication and can be easily confused by capacitive coupling / induced voltages.

E: and again we have proof that great minds think alike, although Tel types faster

 

[srl-8]

Yes, I agree that voltstick is not a 100% guarantee, I will test what voltage is present when I go back to finish the job, just had never noticed this before.

Cable bunching can confuse a voltstick, however, the RCD (to my understanding) should break the power on both live and neutral. So there should be no current available to detect on the load side of the spur and bathroom circuits.

 

[dingledong]

What's wrong with the wet finger method

 

[Lucien Nunes]

no current available to detect on the load side of the spur

No current, indeed. But a voltstick detects... voltage. And a small amount of leakage or coupling from a live cable can cause the isolated circuit lives to float up to a voltage that the stick can detect. Readings needed.

 

[Plonker 3]

This should be in the DIY section

 

[Pete999]

You need to use the proper test equipment voltsticks have their uses but NOT to prove dead or live

 

[trev]

Forgive my bluntness but either learn the safe isolation procedure or make sure your life insurance is up to date mate.

 

[Octopus]

Hi all,

I have install a RCD fused spur on the end of line feed to a bathroom lighting circuit. Thus protecting the bathroom with rcd.

I tested the rcd (manually via the push 'test' button) and it killed the lights and fan as expected.

I used my volt stick to confirm that the cables were dead, but to my surprise , The voltstick was telling me the there was voltage still present. How could this be?

My understanding was that with the RCD tripped, it should kill all power on the load side of the spur, .

Any ideas????

Thanks

What voltage was your MFT showing at a load point after you'd tripped the RCD?

 

[Pete999]

What voltage was your MFT showing at a load point after you'd tripped the RCD?

Think he just pushed the test button, probably don't own a MFT

 

[shanky887614]

Use a multimeter/ MFT rather than a voltstick to confirm what voltage is where. Voltsticks are useful but only give an indication and can be easily confused by capacitive coupling / induced voltages.

E: and again we have proof that great minds think alike, although Tel types faster

i like to think they show potential, potential to injure yourself or generally make yourself look like a --- waving a stick with a flashing red beacon like some crazed harry potter fan

 

[Octopus]

Think he just pushed the test button, probably don't own a MFT

Give the OP a chance, how else would he have recorded the relevent details for the Cert?

 

[srl-8]

All,

I have to say, (with a few exceptions) you come across as a **** taking bunch of smart arses. You all use volt sticks, you are telling lies if you say you don't. I never said that I rely on this method to confirm voltage. It was an observation and wanted to ask other people.

With-in a few replys this forum has 'Assumed' I don't know what im doing.

I future I will think twice before I post. Ouch!

PS: Many thanks to those who offered sensible responses.

 

[Octopus]

All,

I have to say, (with a few exceptions) you come across as a **** taking bunch of smart arses. You all use volt sticks, you are telling lies if you say you don't. I never said that I rely on this method to confirm voltage. It was an observation and wanted to ask other people.

With-in a few replys this forum has 'Assumed' I don't know what im doing.

I future I will think twice before I post. Ouch!

PS: Many thanks to those who offered sensible responses.

In which case you should use the "thanks" button so we can see which ones you appreciate!

 

[telectrix]

In which case you should use the "thanks" button so we can see which ones you appreciate!

i wouldn't hold your breath.

 

[Andy78]

All,

I have to say, (with a few exceptions) you come across as a **** taking bunch of smart arses. You all use volt sticks, you are telling lies if you say you don't. I never said that I rely on this method to confirm voltage. It was an observation and wanted to ask other people.

With-in a few replys this forum has 'Assumed' I don't know what im doing.

I future I will think twice before I post. Ouch!

PS: Many thanks to those who offered sensible responses.

I'm not lying, I definitely don't use them. I have used voltsticks in the past, but in my experience they give false readings either live when dead or vice versa.
If I had used one and got a spurious reading however, my first thought would be to prove with my AVI what was going on, not ask an internet forum. That would give the impression I don't know what I'm doing or have the right tools for the job. I think that is what you have got stick for.

 

[tazz]

Quick few games to show voltsticks pick up stray and non dangerous currents.... place voltstick near tv screen... rub voltsick on your jumper, all will lite the voltstick, but non are dangerous.

 

[Deleted member 72666]

Yes, I agree that voltstick is not a 100% guarantee, I will test what voltage is present when I go back to finish the job, just had never noticed this before.
Cable bunching can confuse a voltstick,
however, the RCD (to my understanding) should break the power on both live and neutral. So there should be no current available to detect on the load side of the spur and bathroom circuits.

This can be overcome by using your finger on the end of the voltstick and slightly separating the cables as you scan.
I use a voltstick on a regular basis and it has served me well over the years in fact I would go as far as saying that it's potentially saved my life on at least a couple of occasions when I unwittingly came across a 'borrowed' neutral, that's after safe isolation was carried out, all appeared okay until I split the neutrals and one magically became live! They're also great for detecting broken neutrals in extensions.

 

[Knobhead]

I would sack any electrician that relied on a voltstick.

I gathered them all up at work and threw them in a kiln. Use recognised test methods.