Gfci & Afci

[gulkhan123]

Q: If the GFCI can detect the low fault level current then why the AFCI is needed for such a condition sometimes in branch circuit?

GK

 

[haskindm]

GFCI detects an imbalance in a circuit - more power going out on the hot than is returning on the neutral conductor, for example. Standard breakers and GFCI's see an arcing fault as a load. Unless this fault creates a large enough current draw to trip the device it will remain energized. AFCI's look for the abnormal sine wave that is created by an arcing fault and open when it is detected. They also have a higher level ground fault detector that will open the circuit if there is an arc to ground or neutral. The two devices do separate jobs using very different methods.

 

[gulkhan123]

Gfci & Afci

GFCI detects an imbalance in a circuit - more power going out on the hot than is returning on the neutral conductor, for example. Standard breakers and GFCI's see an arcing fault as a load. Unless this fault creates a large enough current draw to trip the device it will remain energized. AFCI's look for the abnormal sine wave that is created by an arcing fault and open when it is detected. They also have a higher level ground fault detector that will open the circuit if there is an arc to ground or neutral. The two devices do separate jobs using very different methods.

Reply: Thank you hasindm. yes the methods are different but ultimately both do the same job i.e. open the circuit. Is it not so?

Secondly if AFCI also for detecting the large FAULT current, then only the conventional CB is enough.Why a GFCI? Kindly clarify?

 

[gulkhan123]

Thank you hanksdm. Yes the methods are different but ultimately both do the same job i.e. open the circuit. Is it not so?

Secondly if the AFCI is for detecting large fault current, then only the conventional CB can do this job and open the circuit. Then why an AFCI?

GK