I have a Stoves Newhome EFa600H electric fan oven (model XXXXXXXXX s/no 40946234). Today whilst cooking sunday roast it tripped the consumer unit MCB. Now I have the following faults:1. Initially resetting the consumer unit fuse with the oven on tripped the consumer unit MCB. 2. Once everything had cooled down, I found I could now plug the oven in (oven off) and the rear external fan will run for a second then stop. 3. Switching on the oven and temperature selector either does nothing or (sometimes) trips the MCB.Could you advise what the fault might be? I have a multimeter so can check the various components but do not have the manufacturers expected power, current, resistance, voltage values. I am guessing it is most likely to be the thermostat, oven fan, or circuit board. Please email XXXXX@XXXXXX.XXX XXXXXX@XXXXXX.XXX or phone 07825 992550.ThanksDave
See description on previous page. Have also checked resistance on main element (24 ohms), rear fan (500 ohms), and coil on oven fan (47 ohms.
HiWhilst it is difficult analysing faults remotely, one thing strikes me.Usually when RCDs trip for no apparent reason it is because there is moisture in one of the elements.Modern oven elements are insulated internally with a material which is hygroscopic (it attracts moisture). When the moisture level is high enough (usually when the oven is unused for some time) and then the oven is switched on, the moisture is driven around inside the element, by the heat, and congregates in one place. When the build up is sufficient some of the current travels through the moisture and down to earth thus operating the RCD. When the oven has cooled down sufficiently the moisture re-disperses and the element will test OK.Typically when the oven is switched on from cold, all will appear well, but then (up to some few minutes later) the RCD will trip. Attempts to reset the RCD, whilst the oven is still in circuit, will fail untill the oven cools or untill the main oven isolator is swtched off. Although it is usually the element in use which is the problem, it is not always so. I have had times when the neutral of an unused cicuit becomes leaky thus causing the same problem. (RCDs work by monitoring the current in the Live and Neutral parts of the supply. Any disparity assumes a leak to earth and the device trips if over 30mA)You can proove this with a meter, set on amps, in the earth return. You will see the current build up untill it reaches approximately 30mA when the RCD will trip. Do not do this unless you have a good knowledge of electricty as interfering with the earth path can lead to fatal electric shock.The only real cure is to replace the affected element. I have tried drying-out elements with mixed success.Hope this helps.
Thanks for your thoughts. Before I splash out £65 on two new elements (one oven, one grill) is there anything I can do to test the other parts of the circuit? eg the oven fan, thermostat, timer, circuit board? I cannot carry out your suggested trip test as now I am getting no power to the elements (only the rear fan for a second or so as per point 2 in my previous email). I have a sneaking suspicion the thermostatmight be the problem but don't know how I can test this unit.
Ok, hold on to your cash for the moment. If there is no power to the elements it will be neccessary to check the thermostat and possibly the oven function selector. If you have the option of different functions on your oven you need to check that power is fed through to the elements from here. If there is no option other than fan and grill then the control for this may be on the thermostat. (In this case the thermostat will have a secondary set of switch contacts fitted behind the thermostat itself).The timer feeds power to the thermostat/oven function switch which in turn feeds power to the element and the internal fan. The cooling fan is brought into play at the same time and the small pcb keeps power to the cooling fan for a timed period after the oven has been switched off.The oven timer, controls power to the fan oven element and the internal circulating fan. All these cicuits are discreet and not interconnected so if nothing works at all it sounds like the timer. After the RCD tripped did you reset the timer? The timer must be in manual and with a time set, in order for anything to work.
Domestic Appliance Repair business owner.
You're quite right, after several trips I stopped resetting the clock. Oven is currently running so maybe the element has dried out over the past couple of days and stopped shorting, so I think your moisture theory holds water (excuse the pun!). Thanks for your help.