Hi,
I'm trying to source suitable contractors for a pair of fairly chunky immersion heaters (IH) for my thermal store (TS). Initially I wanted one 6kW and another 9kW IH - these were supplied with the TS. The 9kW IH has 3 separately wirable elements for a 3 phase/415V supply but (according to the manufacturer) can be wired with all 3 elements in parallel to work with 240VAC single phase.
I want to time these 2 IHs to come on only during Eco7 hours and as their thermostats are rated at 16A I intend to control the 2 IHs with a suitably rated contactor and timer all in a DIN rail box - the TS is about 4m away from the main consumer unit.
As it turns out I cannot find a suitable source of the 2m of 10mm 180 deg heat tolerant flex I need to connect to the 9kW element (I am in a bit of a rush) so I am going to use just the 2 elements in parallel to end up with 2 x 6kW IHs. I am going to use 2 runs of 10mm cable from consumer unit to the TS DIN rail box each with its own MCB (one at 45A, the other at 30A) and use similarly rated contactors so that eventually (if indeed required) I can use the 9kW IH at its full capacity. I can obtain 6mm 180 deg heat tolerant flex suitable for the 2 x 6kW IH connections from contactor to element head.
The thermostat/timer/contactor coil signalling cable will also be 180 deg (silicone) flex at 1.5mm.
So, questions:- 1/ Can anyone see any issue with this setup and 2/ can someone please explain the rating info on contactors so I can try to source suitable contactors more cheaply than my electrician can?
My main issue is that the more common (and therefore cheaper) ones are multi-pole - usually 3 pole. If they are rated say at 11kW, is this per pole or for the 3 phases all working together? If the latter then I guess each pole will have a much lower power limit than 11kW? I gather my 6kW IH needs 6k / 240 = 25A (say 30A) rated contacts and the 9kW, 38A (say 45A) ones. Can I connect the poles together in parallel to get an 11kW 3pole/phase contactor to work with 11kW 1 phase load?
Thanks in advance, MW.
I'm trying to source suitable contractors for a pair of fairly chunky immersion heaters (IH) for my thermal store (TS). Initially I wanted one 6kW and another 9kW IH - these were supplied with the TS. The 9kW IH has 3 separately wirable elements for a 3 phase/415V supply but (according to the manufacturer) can be wired with all 3 elements in parallel to work with 240VAC single phase.
I want to time these 2 IHs to come on only during Eco7 hours and as their thermostats are rated at 16A I intend to control the 2 IHs with a suitably rated contactor and timer all in a DIN rail box - the TS is about 4m away from the main consumer unit.
As it turns out I cannot find a suitable source of the 2m of 10mm 180 deg heat tolerant flex I need to connect to the 9kW element (I am in a bit of a rush) so I am going to use just the 2 elements in parallel to end up with 2 x 6kW IHs. I am going to use 2 runs of 10mm cable from consumer unit to the TS DIN rail box each with its own MCB (one at 45A, the other at 30A) and use similarly rated contactors so that eventually (if indeed required) I can use the 9kW IH at its full capacity. I can obtain 6mm 180 deg heat tolerant flex suitable for the 2 x 6kW IH connections from contactor to element head.
The thermostat/timer/contactor coil signalling cable will also be 180 deg (silicone) flex at 1.5mm.
So, questions:- 1/ Can anyone see any issue with this setup and 2/ can someone please explain the rating info on contactors so I can try to source suitable contactors more cheaply than my electrician can?
My main issue is that the more common (and therefore cheaper) ones are multi-pole - usually 3 pole. If they are rated say at 11kW, is this per pole or for the 3 phases all working together? If the latter then I guess each pole will have a much lower power limit than 11kW? I gather my 6kW IH needs 6k / 240 = 25A (say 30A) rated contacts and the 9kW, 38A (say 45A) ones. Can I connect the poles together in parallel to get an 11kW 3pole/phase contactor to work with 11kW 1 phase load?
Thanks in advance, MW.