Hi, question regarding RCDs in CUs.
Even if there is a fault in a circuit or with an appliance plugged into a circuit that is preventing an RCD in an CU from being reset should the RCD reset if the isolator switch on the CU is switched off?
Late last night about 30 seconds after turning on my bathroom lights the RCD protecting that circuit tripped. All the MCBs on that side of the CU were still up, so I turned them all off then tried to reset the RCD but it won't reset. Now I cud spend some time investigating what has caused the trip but I thought that perhaps I cud first eliminate the RCD itself as the problem so I switched off the isolator switch on the CU thinking that if the RCD was ok I wud then be able to reset it but it still won't reset. The CU has 2 RCDs & the other one stays up when the isolator switch is off so I am assuming that, since RCD detect current inbalance they don't actually need a current running thru them to be capable of resetting.
So am I right in assuming that because the RCD won't reset even when the isolator switch is off that the RCD itself is faulty & needs to be replaced.
Thanks
Even if there is a fault in a circuit or with an appliance plugged into a circuit that is preventing an RCD in an CU from being reset should the RCD reset if the isolator switch on the CU is switched off?
Late last night about 30 seconds after turning on my bathroom lights the RCD protecting that circuit tripped. All the MCBs on that side of the CU were still up, so I turned them all off then tried to reset the RCD but it won't reset. Now I cud spend some time investigating what has caused the trip but I thought that perhaps I cud first eliminate the RCD itself as the problem so I switched off the isolator switch on the CU thinking that if the RCD was ok I wud then be able to reset it but it still won't reset. The CU has 2 RCDs & the other one stays up when the isolator switch is off so I am assuming that, since RCD detect current inbalance they don't actually need a current running thru them to be capable of resetting.
So am I right in assuming that because the RCD won't reset even when the isolator switch is off that the RCD itself is faulty & needs to be replaced.
Thanks