點解fuse一定要裝係live到呢!!?

Generally,Hot Wire Carries 220VAC,Neutral Carries 0VAC,
Yep,If Fuse Connect To Neutral,When Current Increases,The Fuse Will Brow-Up,The Circuit Will Be Open At All,It Mean Not Current Flows.aa
But If The Fuse Connect To Neutral,When The Fuse Blows.Although Its Not Current,But If This Time Hot Wire Leakage To Metal(Earthed),We Will Be Electrocuted.(Hot Wire To The Elment Via The Fuse Have Continuity)
But If Fuse Connect In Live,When Fuse Blows.Its No Current In The Circuit,
If The Live Wire Touched The Metal(Earthed)This Time In The Machine.Since The Fuse Blown,It Form A Open Loop For Live Wire To The Elements,
So We Will Not Get Electrocuted.

2009-11-30 23:05:06 補充：
the example of kolam911 is suppose that its leakage.(漏電)

but my example suppose that the current increases suddenly to blow-up the fuse,
I simulate模擬 the situation after the fuses blows.

2009-11-30 23:05:51 補充：
My Speech Exactly Is kwokkwok83 .

其實裝係Neutral到，當係電流( Current I )大於個fuse rating個陣時，個fuse都會斷開既...不過首先你要知道neutral既電壓( Voltage V )係等於0V，佢既作用就係提供一條回路返番發電廠去成為一個閉合電路complete circuit，即係假設你可以將手指插入Neutral個插孔到( 前提係你要打開Earth個閘 )，咁你都唔會電死。

但相反地，Live係提供交流電既位置，電壓就係由220V ~ -220V，即係佢係最危險既位置。當你做到一個complete circuit ( 假設你又係插手指入去，咁可能個circuit就complete by earthing [接地] )，咁你就會電死架喇...

咁而家解釋點解要裝係live而唔係neutral到喇...
首先我以熨斗作為解釋既例子...咁你應該知熨斗就係有條live一路駁入去fuse再接住發熱線 ( resistor ) ，然後由Neutral出番去，另外Earth就會接住熨斗既金屬外殼。
咁我先設一個Case，咁個Case就係譬如fuse同resistor中間個段電線意外地斷左，咁就接觸到個金屬外殼，咁個電流就會由Live經過Fuse，再行wire到金屬外殼，然後去個使用者同Earth，咁因為Earth提供一個極細電阻既路徑，咁電流就會有大部分流向Earth，有小部份流去使者，咁就因為個Current行一條極細電阻既路，咁個Current數值就會好大，咁就會大於個Fuse Rating既數值，條Fuse就會斷...咁條Fuse斷左，即係個circuit斷開左，冇一個complete circuit就唔會有流，咁個使用者就唔會電親。

咁之後到第二個Case，呢個Case就用你講個隻fuse裝係neutral既後果，即係係發熱線resistor之後。咁同樣地，Live同resistor中間條wire又係斷開，咁岩接到個金屬外殼，咁即係電流就會經過Live去到Earth同個使用者到，咁個電流又會係好大喇，咁但係今次冇fuse去break開個circuit喎...即係個電流會Keep住流過Earth同使用者，雖然個電流可能好細，但係好細既電流都足以致命。

睇完以上例子，我諗你應該知道，fuse既作用就係係break開一個唔正常既circuit，而家係Live既原因就係因為要將個條最危險既Live同成個電器分隔開，咁就可以保護到用家既安全。

仲唔明可以add我msn : [email protected]

fuse 裝係 live, 當過流或短路時, fuse 溶斷後, 設備電壓＝０, 對人不構成危險 , 若 fuse 裝係 neutral , fuse 溶斷後　設備電壓＝220 對人構成危險