Hach 911, User Manual

Page: 11 / 103

9
General Information
2.1.4.2 Intrinsically Safe Wiring Practices
DANGER
Intrinsically safe wiring must be separated from non-intrinsically safe wiring to
prevent the transferring of unsafe levels of energy to the hazardous area.
DANGER
Le câblage à sécurité intrinsèque doit être séparé du câblage à sécurité non
intrinsèque afin d'empêcher tout transfert de niveaux d'énergie non sûrs vers la
zone dangereuse.
The following practices are meant to be used as guidelines or recommendations only. For
specific rules or more detailed practiced, refer to the National Electric Code, Canadian
Electric Code, or ANSI/ISA-RP 12.6-1987 or subsequent.
Intrinsically safe wiring must be installed, maintained, and repaired with considerations for
the following:
Connections
Do not connect non-intrinsically safe wiring to intrinsically safe terminations of any
associated apparatus, usually identified with light blue.
Routing
Intrinsically safe wiring must enter or leave the non-hazardous location by the shortest and
most direct route.
Clearances
A clearance distance of at least 50 mm (2 in.) must be maintained between any
non-intrinsically safe conductors and intrinsically safe wiring or terminations.
The only exceptions allowed for minimum clearances are:
• All intrinsically safe circuit conductors are in Type MI or MC cables or
• All non-intrinsically safe circuit conductors are in raceways or Type MI or MC cables
where the sheathing or cladding is capable of carrying fault current to the ground.
Raceways
Raceways should be used to keep intrinsically safe wire and non-intrinsically safe wire
separated. Wire lacing or ties are considered acceptable methods. All raceways for the
intrinsically safe system are identified with permanently affixed labels with the wording
Intrinsic Safety Wiring or equivalent.
Conductor Identification
Intrinsically safe conductors must be identified, either by color coding with light blue
jacketed cable or by tagging, at regular intervals of every 7.62 m (25 ft), as identified by
NEC (National Electric Code).
Voltage Limitations
The electrical equipment for non-hazardous location must not contain a source voltage
greater than 250 V unless sufficient means have been employed to prevent the shorting of
a source voltage greater than 250 V onto the non-intrinsically safe terminals of the
associated apparatus.