Circuit max wattage: mains heating

Old 03-01-17, 09:54 AM
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Circuit max wattage: mains heating

Hi everyone

Thanks for having me. We had storage heating which was removed to make room for gas central heating. In this time, we changed our electricity terrific to a single rate meter and had the living room skimmed and filled in the old storage heating mains connection holes. Long story short; we didn't end up connecting to the gas and are currently without heating.

As a result, we've opted for duplex panel heaters and they work really well, heating the house nicely, and to our suprise, at lesser cost that the storage heating did. They run on 3 prong plugs which plug into a socket (directly - no extention cables).

Recently, a friend of mine mentioned that the mains circuit may not be able to withstand the radiators we have downstairs:

2 x 1500w
1 x 1250w
1 x 1000w
Total: 5250w

This figure is excluding other general house appliances through the livingroom, doning room and kitchen.

I've done a search online and found a lot of information which, if I'm honest, scared me a little with the horrors of house fires and has resulted in the heating not being switched on.

My house is 1970s build and the home report states that some rewiring has been carried out (the sockets downstairs have usb ports for example) however I don't think this lessens my situation in any way. The fuse box states 20a and appears to have 3 socket breakers, though I haven't yet tested where these affect.

Am I safe to have these heaters running

I was hoping someone could let me know what I am safe using and if I am not safe to run them all (continuously when needed) what options do I have to make them safe to run simultaneously.

Many thanks
Old 03-01-17, 12:19 PM
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Hello and welcome. Could you help us by supplying your location? This board is primarily focused on US and Canadian codes, and it sounds like you may not be in those areas. We still may be able to help.

Some general advice: portable space heaters are often a poor substitute for central heating. They are constructed more cheaply and as such not designed for continuous operation, potentially leading to fires. They rely on cord-and-plug connections which are less safe for high power devices than hard wired fixed heaters with dedicated circuits. They're difficult to control and balance leading to uneven and inefficient use of energy.

Continuing with the general advice, a heater should not exceed 80% of a circuit's rated capacity. In this US this means that a 20A 120V circuit should not exceed 1,920 watts of total heaters assuming no other loads; or 1,440 watts for a 15A circuit. You also want to make sure the wiring and receptacles are in good condition to handle the added stress of a space heater. With the construction date of 1970s, you'll want to verify the branch circuit wiring is copper, not aluminum. Aluminum wiring was a lower cost fad in the 1970s and is much less safe with high power loads.
Old 03-01-17, 03:13 PM
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FYI - OP is in the UK, Scotland.
Old 03-01-17, 03:27 PM
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Based on 230v power.

2 x 1500w = 3000w= 6.5A + 6.5A
1 x 1250w = 5.5A
1 x 1000w = 4.5A

Based on 3) 20A circuits...... the panel could run warm.

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