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Topic Title: Heater wiring
Topic Summary: Advice please on best way to wire industrial electric heaters
Created On: 11 December 2012 07:26 PM
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 11 December 2012 07:26 PM
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hullelectrician

Posts: 16
Joined: 04 July 2012

Hi guys

I've been asked to install around 20 electric infa red heaters in a factory.
These are single phase, each element, of which there are 3 per heater is 600 watt, giving 1.8kw per heater. They are suspended on jack chain 3 metres above the ground.
Each heater comes with a 3pin plug top.
My initial thought was to install 4 ring mains into the roof space and plug 5 heaters into each, this would then be 40 amps.
My next thought was 4 10mm supplies to a 4 sub boards in the roof and run 5 sockets off each. But this seems expensive.
I have also thought about a 4mm ring mains on a 40amp mcb but not sure on this.
My last thought is a 3 phase dis board for heaters, and run all 20 heaters as radials.
Any ideas most welcome!
 11 December 2012 07:34 PM
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peteTLM

Posts: 3166
Joined: 31 March 2005

what are the dimensions of this factory?

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 12 December 2012 07:18 AM
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hullelectrician

Posts: 16
Joined: 04 July 2012

Hi Pete

it is a pretty basic rectangular shape of approx 25 mteres by 100 meters.
 12 December 2012 08:59 AM
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broadgage

Posts: 1298
Joined: 07 August 2007

I would be inclined to install 6 radial circuits, each 32 amps and in 4mm cable.
Connect 2 circuits to each phase and up to 4 heaters to each circuit, that would allow for up to 24 heaters.

This presumes that there are 6 single phase ways spare in an existing suitable DB.
If this is not the case, then an additional DB will be required and it might be worthwhile to put each heater on its own 10 amp circuit in 1.5mm cable.
This will require a 63 amp 3 phase supply into the new DB, or perhaps more to allow for expansion.
Contactor control might be advisable, ask the customer if they want this.

If the heaters come equiped with 13 amp plugs then I would retain these and plug them them into sockets installed for the purpose.
Cheap heaters are not allways reliable and a plug and socket simplifies future replacement.
 12 December 2012 02:56 PM
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hullelectrician

Posts: 16
Joined: 04 July 2012

Thanks for that.

I decided to install a sperate DB for the heaters, there where enough spare ways but didint want to fill the main DB to the max.
Wired in 4mm to a double socket, with 2 heaters on each, on a 20 mcb.
10 radial circuits in total.

They will be controlled in banks via contactors.

Thanks for your advice
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