So How Come A 30ms Rcd Is Supposed To Trip In Ms..

[OnlQQker]

Yet when you accidently touch it with human hands it is way longer.

I've done this a few times in my clumsiness and it certainly does not trip in milliseconds!

Just wondered what anybody else thinks.

 

[pc1966]

The typical trip current of ~20mA is not pain-free!

Also it is allowed something like 300ms at 30mA, but 40ms at 150mA, though generally you will see them go at < 40ms at either test.
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I suspect also you might touch below the trip current and possibly grip involuntary until it is reached, making the whole process longer and more painful.

 

[Avo Mk8]

You mean when you accidentally touch live mains? Something I try to avoid.

 

[StephenRowley]

Maybe be a bit more careful remember that an rcd won't protect you against a live neutral electric shock.

As other have said it probably that your not quite drawing enough current to begin with to trip the RCD

 

[Rockingit]

The point isn't that they have curious tripping curves, it's the fact that you're still alive to debate them. Having taken a few 'across the chest' whacks in my time due entirely to other people's idiocy I'm just thankful it wasn't in the 60's.

 

[snowhead]

I can confirm from personal experience that less than the tripping current of a 30ma RCD is fairly uncomfortable across the chest.
And that's it's obviously noticeable to someone who's looking at you when they've said You've just had a shock haven't you?

 

[Rockingit]

I can confirm from personal experience that less than the tripping current of a 30ma RCD is fairly uncomfortable across the chest.
And that's it's obviously noticeable to someone who's looking at you when they've said You've just had a shock haven't you?

Either that, or the realisation that you just flew 12' from where you were a moment ago... 415v up a ladder isn't something you forget very quickly!

 

[Lucien Nunes]

Yet when you accidently touch it with human hands it is way longer. I've done this a few times in my clumsiness

I'd recommend looking at your methods and making whatever changes are needed to reduce the probability of this risk. I've never tripped or tried to trip an RCD via me and I don't intend to. I have had shocks but from internal power supplies within electronics where the unit has to be operating to make tests, not from the mains. It must be 30 years since I had a mains shock and that was when I was an invincible teenager!

 

[OnlQQker]

I'd recommend looking at your methods and making whatever changes are needed to reduce the probability of this risk. I've never tripped or tried to trip an RCD via me and I don't intend to. I have had shocks but from internal power supplies within electronics where the unit has to be operating to make tests, not from the mains. It must be 30 years since I had a mains shock and that was when I was an invincible teenager!

I kind of guess your explanation makes a lot of sense Sir.
But here's the thing, Meggers/Fluke/Kewtech testers all measure the trip time and give you the readings which is all very well.
But in the real world these Rcd things are supposed to protect people in situations that I'm describing above. Yet they don't tend to work the same with a human as they do with a machine.
Now I'm only a hobbyist and no way would class myself as an electrician whatsoever, I find electrics fascinating but also have a huge respect towards them.
Yet trusting the readings of a machine is all very well, but in the real world where human life is at stake then this makes me feel a tiny bit uncomfortable.



I'm assuming of course the manufacturers of RCD's test them as well on machines as I can't imagine the companies are paying people to hold on to a live current to measure trip times.

Something just doesn't sit right, and yes it could be a faulty RCD but I'm not talking of once or twice. I'm talking of a few times, even when electricians have been in and done all the tests.
I don't plan on accidently touching anymore, my testing days are over!

Lastly, I have been around electricians since I was 15, I've met and worked alongside a good few. It was always explained to me that an RCD will measure the current going out and the current coming back in. When the balance is broken it is supposed to trip nearly immediately.
Yet it doesn't?

 

[StephenRowley]

I kind of guess your explanation makes a lot of sense Sir.
But here's the thing, Meggers/Fluke/Kewtech testers all measure the trip time and give you the readings which is all very well.
But in the real world these Rcd things are supposed to protect people in situations that I'm describing above. Yet they don't tend to >

Did you die? No therefore they did what there meant to and stopped you dieing. It's not there to stop you feeling pain or discomfort it's there to stop enough current flowing though you that could stop your heart beating ie no more than 30mA(depending on RCD rating). Any current flow less than that will still hurt but not trip the RCD and hopefully not kill you. Your also thinking that current will flow stright at its maximum to begin with it won't, the current will ramp up as the voltage creates a ionised path. So you'll feel pain untill the current flow is high enough to trip the RCD. Also if you short the live to neutral with your body the RCD will see no inbalance in current and you'll get the full wack from what ever the breaker is rated too so I'd suggest that you stop messing around with mains power.

 

[StephenRowley]

The reason for them not tripping at lower currents is that no electrical system is prefect and there will allways be some current leakage to earth.

 

[ipf]

What the hell are you 'touching accidentally'?

Are you literally testing them physically.....as a hobby?

If so, find a safer hobby......... high wire walking or swimming with killer sharks, maybe.