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missy avatar image
missy asked

Why did the breaker blow?

I have a Victron 12 500 20 Multi. I used the correct recommended cable sizes to connect it and it has a 100A breaker between it and the leisure batteries.

It runs through a consumer unit with 16a mcb to the sockets.

It turns on in inverter mode, and I get power in my 230v sockets - I used a test plug to show no faults.

When I plugged in a 250watt heater the alarm led flashed on the multi and the breaker switched off.

I thought I could run appliances up to 500watt on the inverter, so why did the breaker blow?


Thanks!

Missy

inverter current draw
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Anil Ghatikar avatar image Anil Ghatikar commented ·

Most probably short in the heating element


I noticed the heater has a regulator. Can you try on a lower setting? If you have access to a multimeter you can check the resistance of the heater directly to determine the wattage

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Mark avatar image
Mark answered ·

Are you sure that the heater is really only 250W?

That is very low power draw for a heater.

Maybe recheck the label again. It could have stated 250V or 2500W maybe?

Alternatively, use a 240V power monitor and plug it into a mains outlet to measure what it really draws. You can pick them up quite cheaply from hardware or electronics stores and they often come in handy.

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missy avatar image
missy answered ·

Thanks!

It was this one...

Dimplex Ddf250 Personal Desk Heater with USB Charging Port, 250 Watt, White with Silver Trim https://www.amazon.co.uk/dp/B072MFNRX2/ref=cm_sw_r_wa_apa_i_qCd1Cb58WDP7V

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Mark avatar image Mark ♦♦ commented ·

I looked it up & also had a look at the manual. There is no clear max power specified, just heat output. It should be about the same for a 'simple' electric heating element, but in reality I think that it's drawing much more than 250W & that's what's overloading your inverter/blowing your fuse.

I also saw in the heater manual that it has a 13A fuse fitted - which is huge for something that suposably only draws 250W...

To find out for sure, just get yourself a cheap 240V plug in energy/power meter & test the real power/current draw. Otherwise your just guessing.

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moonlightrider avatar image
moonlightrider answered ·

Better check the real power draw from the heater with a watt meter and if possible with an TRMS clamp meter, that would give you real current readings.


If the breaker between batteries and inverter also 'blown', that heater is probably sucking much more than 250W. (at least until it reaches 'nominal temperature' and then power draw may be close to 250W)

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graham avatar image
graham answered ·

Which breaker did it switch off the 100A or the 16A in the consumer unit?

If it was the 100A DC one was it one of these https://www.amazon.co.uk/Qiorange-12V-24V-Circuit-Inverter-Protection/dp/B07F3YHMXF?ref_=fsclp_pl_dp_2 or https://www.ebay.co.uk/itm/12V-24V-DC-Home-Solar-System-Waterproof-Circuit-Breaker-Reset-Fuse-Inverter-UK/163489976749?var=&hash=item2610c311ad&enc=AQADAAADAFjVrDbVsZ8oH%2F8PNHtt9VX4%2Fw7FZcmMuqsX8uaFEduVVg6Rqgi90YP6trwFWcl8qtA%2FjpKNA1Dso%2FuAv8qgddT8jIX9zavBQJ5kN0Yr5ptO8OFoLSoVqNoXmegoHLa1%2FHOVbex7CRHRMLfhnaHJnu8J32nX0X9v3ttOPoH2Ej3yO420wNR2x6x0NOu55xqf%2BzzzP6Ud%2F8JfO2CioLYMa2uQfgt9Q7nSZVov%2BOvS733ZuwNzHhDXXA21KPHxFfy1x8qtDzPDdfTUm02s%2F1D44nQ7QG%2FR6a9diat9tqVc%2FlSpWpdB1WkkwPx7tOAYRdWhcK5ZpVrlOfWxlnlfyPhQpCwo8YPHgYQArT6F%2BV94K1p%2BRexJmk1XSyOlPhS8g27A5fxDJnwpoeiI2ys%2BKSTbiARp6DORexEZA%2B6PT9rLu%2BRz2TbdcPmHXBlJUmrcaz2CfjOyD4NXSy1VsvxmklqJuRgM3k6mplDaU6lid%2B0kRPZ%2Ffun5TM%2FulpDz8GMm4s8610JMBOg8xlul51SZkUBUUSqrhGUYPkTTrjv9Cj4TdCQtlCDPIkc7UAJgF4sbJrf%2FlEK%2B2T5y5TOmcOG5NC5xMYrLIFkNg6W%2Fp%2BzRf%2BLKQLRlQrZntJ%2FfJxSmYw8kdxZm570wTV4qxGHxXTtelPJKb%2BlbpCivZUJHncM1OJHjgSP%2FxxaHzned9LMa%2BcODRN1Ew11K97v%2FVki9NE%2BoR9VEuQtL%2BpbGJJ4qSiRqSZP6var%2BlTYYKs2Eniedx5subZTKbZPwcbMSU0YBc%2FPX6Wx35V2DagvuGBibIeS1Fee%2F2Pf2Vrx%2F6fxbhs%2FtHcFVh6lquC3vmNrntykfSFEm8DQ%2FNncEzv8oVo%2FFZeh9sH3NQvuhWi%2BmXdRzH3Rp5YQ5UWyG5wU%2Bc3y4JtxdYNUvLCsdRg3C9dO0UKZpBaxLd%2FIEYCnl1%2B4UDNaCZybGApQ1sdBzs3ArHLePtGTG%2FLsQgput8qTB4udxkw1S2IDdOBhQ0A3mbGyWt%2FgzVZX0MzxyxocPGg%3D%3D&checksum=163489976749fe0340500c6e458db1d855a9da7ffea6


The heater has a fan and at start up it will draw quite a lot of current , also the DC breakers of the type above tend to be sensitive toward their top end and switch off early. Also there is a possibility that the heater could be faulty

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missy avatar image missy commented ·

It was the 100a breaker. Similar to the one you showed. I think the heater must just draw more than 500w on start up, and most people never know or care because in a house or office you don't really need to know!

Thanks!

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Anil Ghatikar avatar image Anil Ghatikar missy commented ·

I sincerely doubt the breaker will trip due to fan starting current. Similar breaker from Bluesea systems trips after 10 sec on 200 Amps or 1 SEC after 400 amp

https://www.bluesea.com/products/7144/187-Series_Circuit_Breaker_-_Surface_Mount_100A

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