faulty oven

[joko]

my oven has started shorting the power to the whole house, as soon as i turn it on.

I have done a variety of minor electrical jobs around the house as well as a module about lighting rigs at college so have a basic knowledge of wiring etc.

would it be safe for me to take the box off the wall and change the fuse (is there one??) i don't know anything about ovens and why they are wired in that way.

or is it likely to be a problem with the cooker itself rather than a fuse? can't really afford to get someone out to look at it.

if someone could explain it to me or advise me to keep away, i'd be grateful (obviously i'd turn it of at the mains first!)

[BillyNoMates]

Sounds like the element or one of them in your cooker has started to 'age' and has a leak to earth.

You don't mention how it's tripping the power to the whole house - it it tripping the main breaker ? Is this an RCD breaker (it will say on it) ?

[joko]

Hi BillyNoMates

The power to the whole house just goes off and will only come back on by flipping the trip switch back on. Cant see RCD on it but it says on it (its a fairly oldish box) -

240v 50hz

63a load

30m A Trip

CAT WES 63/2

current operated earth leakage circuit breaker

(brand name is wylex)

this is all it says on the front

it has on/off switch and a 'test monthly ' switch.

there are 6 fuses (one has a red front) and the fusewires are all checked and fine.

does any of this make any sense to you?

thanks for your help

[Carol Anne]

Don't fiddle around with this!! Look in your local paper's classifieds for an electrician, they're usually a lot cheaper than the ones from the phone book.

[joko]

i haven't done anything connected with the mains in years, and they were only simple things like new light fitting and connecting a new light switch, following step by step instructions.  

other jobs were not connected to the mains and relate to appliances, plugs, extension leads etc, and building a computer.

 these have all been fine and never caused a problem. the cooker has always been fine too.

this only occurs when the cooker is switched on.

i just  need to know if it can be fixed as simply as changing a fuse.

[tony1941]

The ELCB you have in your system is intended to detect leakage to earth of the live circuitry, however, a side effect is that it will trip if you have a connection anywhere in the house between neutral  and earth.  Check you haven't done this inadvertently in your additions.  (suggest you start by removing everything added - and be careful!!)

[shaunjosh]

If it's only happening when the cooker is switched on - it will be the cooker that is the problem. The element will be breaking down as it heats up, causing the ELCB to trip. Although elements are fairly easy to source and change, you are probably better off getting a qualified electrician to do it. Although ELCB's, RCD's etc are very protective , they can be a nuisance. Irons, fridges (as the compressor kicks in) can cause them to trip with the smallest of leakage current, even though there is nothing really wrong with the appliance.

[Tim B]

Just to clarify.  The earth leakage circuit breaker (trip) compares the current flowing in the live and neutral lines.  If there is any difference it means that difference in current is flowing along the earth line or through a different path to earth (maybe plumbing pipes etc).  It is designed to trip when this difference exceed a certain amperage of current flow.  It is not designed to protect against a short circuit but only when current does not return via the neutral line.

This suggests (as mentioned before) that although parts of your cooker may not be short-circuiting (between live and neutral) they may be physically 'shorting' to earth.  This would not pose a problem if humans were not involved.  But, because you may touch the metal of the cooker, you will become part of the current path to earth and have a current pass through you.  It only take a few milliamps (a few thousands of an Amp) to kill you.

Please get a qualified electrician in to sort it.