The element has gone on oven but starting today, it started tripping the house circuits as soon as I turn the knob to a heat setting.

I was going to just replace element but I'm worried something else is wrong as it has started tripping the main switch for the house.

Any ideas?

Is it tripping the main switch or the RCD? (it has a "test" button in the middle of the outlet) If it's an RCD, more likely than not it's because 1) the housing has a leak and 2) water or moisture are getting into the electrical parts, causing a short circuit. You can solve the problem by isolating which element has the leak (disconnect the oven from the power and all elements completely from the oven. Test with an ohm-meter. Each should test at infinite, as they have no grounding), let the wiring dry out (you can use the other elements to do this, for about an hour) and replace the faulty element.

Hope this helps! http://www.suite101.com/content/troubleshooting-an-electric-range-a47592

I would reset breaker, turn on something on Range, or if it has a display, it has power, Turn off breakers 1 by 1 to determine which is the Range breaker.(Need to find out if it is on a Breaker first).
The above Poster mean to to say infinate resistance between element and ground. The element should actually have a Low resistance.
I would check main breaker for loose connections, burnt buss.
Visually check all wiring to all elements, electrically if possible.

Obviously, you have a dead short where the element is wired between the switch and the oven element. You have to replace the wire with a pre-made wire with special high-temp leads on the ends. The element could also be bad. You will have to pull it out and remove panels to get at the wiring sometimes. You will need to unplug it and use an ohm meter to find the faulty wire, but your eyes are your best instrument when looking at the wires. You need to check the wiring and find the bad one that has zero or near zero ohms to ground and trace it. DrTom4444