Automatic disconnection of supply

[rich3009]

How about electrical separation can this afford basic protection

 

[rich3009]

.

 

[rich3009]

.

 

[Risteard]

Because by definition basic protection stops the flow of current and also by definition an RCD provides basic protection regulation 131.2.1 says it does,

Where does Regulation 131.2.1 state or even imply that an RCD provides basic protection?

Also I would suggest that basic protection prevents you from coming into contact with live parts as opposed to stopping the flow of current. (We used to refer to it as protection against direct contact.)

 

[rich3009]

Don't get me wrong I totally understand the principle I'm simply pointing out the ambiguity of the regs

 

[Risteard]

How about electrical separation can this afford basic protection

Electrical separation is in no way comparable to an RCD. This gives us two phase conductors with no neutral or Earth reference.

 

[Risteard]

Don't get me wrong I totally understand the principle I'm simply pointing out the ambiguity of the regs

But I don't accept that it is in any way ambiguous. That's why I am asking where precisely you believe that the Regulation in question supports your claim.

 

[Deleted member 26818]

Since when did an RCD limit the current to a non hazardous level?

 

[rich3009]

By time limited fault duration

 

[Risteard]

By time limited fault duration

Limiting the time isn't the same as limiting the current, though, which is what the Regulation stipulates.

 

[Deleted member 26818]

It also won’t limit anything in a short circuit situation.

 

[Wilko]

The title of reg 131.2.1 is : Basic protection (protection against direct contact)
I know I'm simple, but I don't need to think much beyond that do I?

 

[rich3009]

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

 

[rich3009]

Why is an RCD designed to detect 30mA there is a reason, because fault currents start at zero and climb in a time curve. And at 30mA we want it off and quick

 

[Risteard]

fault currents start at zero and climb in a time curve

No they don't. Ohm's Law is what you need.

The thermal effects of the fault increase - the fault current is simply a product of the voltage and impedance.