I'm putting in a hot water tank with an immersion heater.
The hot water tank will be located in a loft.
I want to put an on/off switch on the wall in the utility room, so I have an MK 20A 'water heater' switch.
But I figure the immersion heater should have a local isolator right next to it, and have a 13A fuse between it and the final circuit. Also I need somewhere to terminate the (presumably heat resistant) one metre immersion heater cable. So I have a switched 13A FCU to go next to the immersion heater.
The power for this whole deal is supplied by a 16A final circuit assigned for heating (pumps & controllers etc) and immersion heater.
As it is only a 16A circuit, the 20A remote switch could be put in circuit either before or after the FCU.
If the 20A remote switch is before the FCU, then it makes the wiring simple. We just link as: CU - 20A remote switch - FCU - immersion heater, using the existing terminals on each accessory.
If the 20A remote switch is after the FCU, then we need to go: CU - FCU - 20A remote switch - junction - immersion heater.
The junction is needed because the cable coming up from the 20A remote switch will be 2.5mm² T&E, but the immersion heater needs to be fed with immersion heater cable. So this would need either a bit of 15A terminal blocking inside the FCU enclosure , or a separate junction box.
So I was wondering if there was a standard recognised approach for doing this.
The hot water tank will be located in a loft.
I want to put an on/off switch on the wall in the utility room, so I have an MK 20A 'water heater' switch.
But I figure the immersion heater should have a local isolator right next to it, and have a 13A fuse between it and the final circuit. Also I need somewhere to terminate the (presumably heat resistant) one metre immersion heater cable. So I have a switched 13A FCU to go next to the immersion heater.
The power for this whole deal is supplied by a 16A final circuit assigned for heating (pumps & controllers etc) and immersion heater.
As it is only a 16A circuit, the 20A remote switch could be put in circuit either before or after the FCU.
If the 20A remote switch is before the FCU, then it makes the wiring simple. We just link as: CU - 20A remote switch - FCU - immersion heater, using the existing terminals on each accessory.
If the 20A remote switch is after the FCU, then we need to go: CU - FCU - 20A remote switch - junction - immersion heater.
The junction is needed because the cable coming up from the 20A remote switch will be 2.5mm² T&E, but the immersion heater needs to be fed with immersion heater cable. So this would need either a bit of 15A terminal blocking inside the FCU enclosure , or a separate junction box.
So I was wondering if there was a standard recognised approach for doing this.