15-11-2013, 07:39 AM
There is some debate over whether an outdoor circuit, such pwdrive's caravan, should have its RCD at the source or destination. It must have an RCD (since 15th ed) since it's outside the equipotential bonding zone.
The armoured cable itself need not be covered by an RCD since it's protected by an earthed surround but it's still nice to have the extra protection. The reason for having the RCD at the load end is convenience if it trips. Think of user stumbling back to house in darkness to reset the RCD.
Cascading RCDs is a waste of time. Even if they are rated at different trip currents there's no guarantee about which will trip first in the event of a fault. That would need a time delay RCD (relatively rare and expensive) in the upstream position.
The armoured cable itself need not be covered by an RCD since it's protected by an earthed surround but it's still nice to have the extra protection. The reason for having the RCD at the load end is convenience if it trips. Think of user stumbling back to house in darkness to reset the RCD.
Cascading RCDs is a waste of time. Even if they are rated at different trip currents there's no guarantee about which will trip first in the event of a fault. That would need a time delay RCD (relatively rare and expensive) in the upstream position.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
