270 likes | 589 Views
Wiring a plug. Fuse. Objectives. how do fuses work? what job do they do? how do you calculate which fuse to fit?. The domestic plug. E A R T H WIRE. LIVE WIRE. FUSE. NEUTRAL WIRE. CABLE GRIP. Anatomy of a fuse. non-conducting ceramic/glass body. low melting point fuse wire.
E N D
Wiring a plug flippedaroundphysics.com 2016
Fuse flippedaroundphysics.com 2016
Objectives • how do fuses work? • what job do they do? • how do you calculate which fuse • to fit? flippedaroundphysics.com 2016
The domestic plug EARTH WIRE LIVE WIRE FUSE NEUTRAL WIRE CABLE GRIP flippedaroundphysics.com 2016
Anatomy of a fuse non-conducting ceramic/glass body low melting point fuse wire symbol flippedaroundphysics.com 2016
Fuse - normal operation Fuse – current too high flippedaroundphysics.com 2016
Normally working appliance Metal casing LIVE fuse NEUTRAL EARTH flippedaroundphysics.com 2016
Appliance with a fault Metal casing LIVE fuse NEUTRAL EARTH flippedaroundphysics.com 2016
Fuses come in different sizes 3A, 5A, 13A Which would you choose for a washing machine needing 11.2A to work properly? Which would you choose for a table lamp needing 1.6A to work properly? flippedaroundphysics.com 2016
Choosing the correct fuse Find out the power rating of the appliance 2) Using current (A) = power/voltage calculate the current that the appliance needs (remember that mains voltage is 230V) 3) Choose a fuse that is slightly larger than the current needed flippedaroundphysics.com 2016
Example A stereo system is rated at 800W. What fuse Should be fitted? Current = power/voltage = 800/230 = 3.48A Therefore a 5A fuse should be fitted flippedaroundphysics.com 2016
Calculate the current needed by the following appliances and the fuse needed. flippedaroundphysics.com 2016
A hairdryer doesn’t have an earth wire. Can you think why not? It is made of plastic. Therefore, the casing can’t become live. flippedaroundphysics.com 2016
Such appliances have this symbol. They are “double insulated” flippedaroundphysics.com 2016
switch electromagnet Circuit Breakers Can you work out how they work? flippedaroundphysics.com 2016