AFI & CACFI

In the USA they also have AFI and CACFI. These are extremely complicated and expensive protection devices. However it is understood that there will be a requirement in the next set of UK Electrical Regulations for AFI’s to be installed.

These devices offer protection against electric arcing but AFCIs provide no specific protection against “glowing” connections also known as a High Resistance Connection.

The AFI breakers will trip under these conditions:

(1)The breaker detects a downstream overload or short circuit (per trip curve)
(2)The breaker detects a downstream current to ground in the range of 30-50ma or greater, regardless of the load.
(3)The breaker detects an upstream or downstream arc in that circuit that meets certain preset conditions (“arc signature”), plus at the same time the breaker is carrying 50A or more of load current, even if very briefly. This 50A maximum value used in QO and HOM AFI breakers is lower than UL1699 value of 75A for arc-fault circuit breakers.

CONCLUSION:Square D/Schneider Electric AFI Arc-Fault Circuit Breakers are designed to provide protection against overloads, short circuits, and parallel arcs (H-N), and will trip on current to ground in the range of 30-50mA or higher.

The CAFI breakers will trip under these conditions:

(1)The breaker detects a downstream overload or short circuit (per trip curve)
(2)The breaker detects a downstream current to ground in the range of 30-50ma or greater, regardless of the load.
(3)The breaker detects an upstream or downstream arc in that circuit that meets certain preset conditions (“arc signature”), plus at the same time the breaker is carrying 5A or more of load current, even if very briefly. The 5A value is per UL1699 for combination-type arc-fault circuit breakers.

CONCLUSION:Square D/Schneider Electric CAFI Combination Arc-Fault Circuit Breakers are designed to provide protection against overloads, short circuits, parallel arcs (H-N), and series arcs (H-H same phase), and will trip on current to ground in the range of 30-50 mA or higher.

The protection devices listed above offer absolutely no protection against HRC, it is not what they are designed for. Protection against HRC in consumer units and distribution boards can only be achieved by installing ThePIP System.

ThePIP®
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