Discuss Automatic disconnection of supply in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
I know it's not true but based on that reg alone it states :
Basic Protection
Persons and livestock shall be protected against dangers that may arise from contact with live parts of the installation.
This protection can be achieved by one of the following methods:
Now taking that to the letter without referring to any other regulation an RCD does exactly that, this is a very poorly written regulation and would afford you great defence in court.
- Preventing a current passing through the body of any person or any livestock
- Limiting the current which can pass through a body to a non-hazardous valve
I know it's not true but based on that reg alone it states :
Basic Protection
Persons and livestock shall be protected against dangers that may arise from contact with live parts of the installation.
This protection can be achieved by one of the following methods:
Now taking that to the letter without referring to any other regulation an RCD does exactly that, this is a very poorly written regulation and would afford you great defence in court.
- Preventing a current passing through the body of any person or any livestock
- Limiting the current which can pass through a body to a non-hazardous valve
I know it's not true but based on that reg alone it states :
Basic Protection
Persons and livestock shall be protected against dangers that may arise from contact with live parts of the installation.
This protection can be achieved by one of the following methods:
Now taking that to the letter without referring to any other regulation an RCD does exactly that, this is a very poorly written regulation and would afford you great defence in court.
- Preventing a current passing through the body of any person or any livestock
- Limiting the current which can pass through a body to a non-hazardous valve
It means that it will operate if there is a nominal 30mA earth fault current through it (between 0.5 and 1 times this in reality). So if you were in contact with a phase conductor and 30mA passed through your body it should operate. The 30mA rating has nothing to do with limiting the fault current to 30mA as this would defy Ohm's Law.Why do we have a 30ma RCD if the result is a pass through of a massive current, it would make a mockery of it
Depends if you got any leakage to earth, failing that it would do nothing
Fair point no protectionOk lets for the sake of this stupid thread lets presume theres no leakage, except in his y fronts
To protect human life.I see so what's the point of that level, 30mA
But if the result is an instant huge fault current that starts way above that figure why have it, hence my argument that the fault current grows from zero and fast.. In milliseconds; but is nipped in the bud by the RCD before it gets the chance. Plus if your argument is true why doesn't a 500mA protect you.To protect human life.
It's not about limiting the current to 30mA but ensuring that it operates if 30mA is passing through - well actually 150mA for additional protection to operate within 40mS.
But if the result is an instant huge fault current that starts way above that figure why have it, hence my argument that the fault current grows from zero and fast.. In milliseconds; but is nipped in the bud by the RCD before it gets the chance. Plus if your argument is true why doesn't a 500mA protect you.
Tells me nothing I don't already know
Wise because I'm a firemanMust remind myself not to call you if I need electrical work doing.
Imagine you’re outside mowing your lawn with your hover mower.Well I would like to know the science behind how it saves your life if it doesn't limit the current your body receives
..Only any good with 230-250V AC. to earthWell I would like to know the science behind how it saves your life if it doesn't limit the current your body receives
A current limited power supply and not really much else...But it states you can achieve it by reducing the current to a non hazardous level I would like to know how, and if an RCD can't do it what can
Rcds are advertised to operate at 30ma but they are actually manufactured to function at 27 to 28ma. Manufacturers hedging their bets on that one30mA RCDs are designed to trip when they detect earth leakage greater than 30mA.
Most will trip below this figure.
So if an RCD detects an earth fault current of 4600A, it will trip, and it will trip within 40ms.
An MCB will also trip if it detects a fault current of 4600A, though it is more likely to trip instantaneously or within 10ms.
Where RCDs are good, is that they will trip at lower currents which an MCB might not trip at, or may take seconds, minutes, hours or even days to trip.
So no, RCDs do not limit fault current, just as fuses and MCBs don’t limit fault current.
Never ever assume an rcd will save your life from being killed.Well I would like to know the science behind how it saves your life if it doesn't limit the current your body receives
An RCD functions to disconnect before most fatal events occur in accordance with the below graph, the disconnection time is such that the human body should be able to withstand the expected fault current flowing through the body for that duration without death, but not without pain and reaction, in most cases.
- Preventing a current passing through the body of any person or any livestock
- Limiting the current which can pass through a body to a non-hazardous value
Wise because I'm a fireman
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