The IEEE-1394 standard specifies the following maximum cable lengths:

 

Bus TypeCable TypeMax LengthSpeed Limitations
1394a
4-pin or 6-pin shielded TP copper
4.5 m
400 Mbps
1394b9-pin shielded TP copper
4.5 m
800 Mbps
1394b
Unshielded TP
4.5 m
800 Mbps
1394b
Unshielded TP
100 m
100 Mbps
1394b
Glass optical fiber (GOF)
100 m
(Check with the manufacturer for speed/distance limitations).
1394b
Plastic optical fiber
50 m
(Check with the manufacturer for speed/distance limitations).

Some manufacturers sell cables that exceed the above specifications. In some cases, longer (e.g. 20m) cables can only be achieved by reducing the maximum bus speed to S100.