6ka or 10ka xxxxxxxx

[TJC1]

Do you always need to fit 10ka MCBs or RCBOs on a three phase installation?

How do you decide whether to fit 10 or 6?

 

[Bobster]

Potential fault current.

 

[Andy78]

Measure the PFC ?

I rarely find I'm working on installs where it is over 6kA, but you'll find the 10kA ranges have rcbo leads that actually reach the neutral bar whereas the 6kA ones won't.

 

[James]

agree with both posts above, but be careful if you are determining pfc by measurement when really close to the transformer. I.e if in a plant room containing the transformer and the board you are working on.
most test gear measures loop impedance wrong when really close to supply transformer.

 

[Pete999]

Do you always need to fit 10ka MCBs or RCBOs on a three phase installation?

How do you decide whether to fit 10 or 6?

By measuring/calculating the PFC.

 

[Deleted member 26818]

I quite frequently install 10kA rated MCBs in domestic installations.
Simply because that’s all they seem to have at work.

 

[M4SSO]

The fault rating of the MCB should be determined by the energy let through of the upstream protective device.