Replacing an old, coil-type kitchen electric hob with one of the sleek new glass-top models might be more of a challenge than the weekend do-it-yourself project it may seem to be at first. In addition to the hundreds of dollars you typically spend for a modern hob, you might have to pay an electrician to do some rewiring and change at least one of your fuse box's circuit breakers.
Lift your old hob out of the counter top as though you were opening the bonnet of a car. Grasp it by the front edges and lift. Some hobs have support pegs that can prop the hob open. Scan the underside for a manufacturer's label that tells the amperage rating of the hob. If there is no label or otherwise obvious means of determining the amperage of your current hob, the safest way to proceed is to call an electrician. Alternatively, you can disconnect the hob electrically and take it to an electrician for evaluation. Either way, it is essential to know the amperage rating of the hob you are replacing.
Measure the hole in the counter top into which your current hob fits. This is especially critical when replacing hobs in granite counter tops.
Shop for hobs that match the amperage of the hob you are replacing. Unfortunately, many old coil-type hobs use only 30 amps, while most modern, glass-topped ones demand 40 or 50 amps. This can mean you have to replace the 240-volt wiring to your kitchen and the 30-amp fuse and circuit breaker in your fuse box with those rated for 40 amps or 50 amps.
Replacing the wiring might be necessary because old 30-amp circuits typically used 10-gauge wire while the newer 40-amp and 50-amp ones call for 8-gauge.
Trip the circuit at your fuse box, and then in the kitchen use your electric line tester to make sure there is no current running in your 240-volt electric line. Using screwdriver and pliers, attach the wires from the new hob to the 240-volt lines, following the wiring instructions supplied with the new hob.
Drop the new hob into the hob hole in the counter top. Some models provide instructions for attaching the hob to the counter top. Reset the circuit breaker at the fuse box. Turn on the new hob to ensure that it is operating.
Match the amperage of your new hob to the amperage of your home's 240-volt wiring. Trying to run a 40-amp or 50-amp hob on a 30-amp circuit, especially if you turn on more than one or two of the burners at any one time, can mean frequent trips to the fuse box to reset the circuit. If you are unsure of your own electrical abilities, hire an electrician to install your new hob. The money spent can give you peace of mind that your installation meets current building codes and that your new appliance will not overtax your home's wiring system, thus risking overheating and possibly a fire.
Don't try to disconnect your old cook top--or to connect your new one--without ensuring that the 240-volt power to your kitchen has been turned off. Make sure the circuit breaker at the fuse box is in the off position, and use an electrical current tester to ensure that there is no current running in the two 120-volt lines to your kitchen before you touch them.