Do MCB's provide shock protection?

[Jamesy]

I have been giving revision papers for my fault finding exam tomorrow. Here is one of the questions that i dont get. "How would you check shock protection of an MCB?" I was thinking MCB's dont provide shock protection, they just protect the circuit conductors! I know an RCD provides shock protection though? I would be suprised if at level 3 stage i had got this wrong or it was just a typo i dont know.. And how do you check for shock protection of an MCB?

 

[JUD]

RCDs are "additional protection" and are not always a requirement.

To check the shock protection of an MCB means ensuring Zs is sufficiently low enough so that enough current flows to operate the MCB in the required time in the event of a fault.

 

[johnboy6083]

It's shock protection if it trips below 40ms. A circuit at greater than 32A will have a max disconnection time of 5 seconds, because it is most likely a distribution cct, or a larger item of equipment.

 

[JUD]

It's shock protection if it trips below 40ms.

That should be 400ms (0.4s)

 

[Jamesy]

RCDs are "additional protection" and are not always a requirement.

To check the shock protection of an MCB means ensuring Zs is sufficiently low enough so that enough current flows to operate the MCB in the required time in the event of a fault.

Chers JUD!

 

[Farmelectrics]

as we no for a 32ma rcd needs to trip under 40ms what is the value for x1 generally when i do my tests it trips in 18ms to 28ms but is there a max value for x1 or is it ok if it trips in under 40ms

 

[jumpin jax]

I think you mean a 32a rcbo

 

[Farmelectrics]

yes sorry jax i did mean an rcbo

 

[Bill Beng]

32A 30mA BSEN61009 RCBO
X1 300ms max
X5 40ms max

 

[Farmelectrics]

cheers bill