Gra wrote:
All work has been done by qualified elections no worries there. And the meters have been changed over to digital for the pool off peak so if any thing was wrong won would think they would notice . I am just curios as to the 20 amp breakers I all ways thought lights where 10 amp and gpo's where15 amp Gra..
Circuit breakers and fuses are rated slightly higher than the circuit they are protecting, e.g. 10A GPO's usually have a 15A protection, 15A circuits have a 20A and 20/25A usually have 32A device protecting. This is sometimes called the "headroom". It attempts to avoid situations of circuit overloading and annoying trip-outs caused by using appliances (or too many appliances) that may use more than the rated outlet, e.g. if you had a fridge, toaster, coffee machine, grinder, dishwasher, microwave and all sorts of other appliances all running at the same time on the same circuit, the current draw may exceed the rated level (typically, kitchens in most houses have a seperate power circuit for this reason). The other purpose of headroom is that some types of equipment, say pumps, motors, etc. have very high startup current that lasts for milliseconds. When this is averaged out over the "lag" time to melt a fuse or trip a circuit breaker, it just provides a little bit of space to again provide some buffer against annoying trip-outs. A fuse or circuit breaker is primarily there to protect against excessive currents generated by a short-circuit (as opposed to leakage to earth from some resistive appliances like irons, kettles, toasters, motors, etc. - this is what the circuit-breakers with earth-leakage protection can do - pickup very small leakages measured in milliamps). When a short occurs, you are talking about many hundreds of amps for a split second - this is what melts the fuse wire or heats the bi-metal strips in circuitbreakers to trip them open.
