Eaton MTL

MTL Instruments Group

Facts and Conversions

Facts and Conversions

    Area Classification

    Guideline figures Flammable atmosphere present Standard
    Continuously > 1000hrs/annum Intermittently >10 < 1000hrs/annum Abnormally <  10hrs/annum
    IEC / Cenelec / Europe Gas Zone 0 Zone 1 Zone 2 IEC 60079-10
    Dust Zone 20 Zone 21 Zone 22 IEC 61241-3
    North America NEC 505 Gas Zone 0 Zone 1 Zone 2 Listed in NEC 505-5
    NEC 500 Gas & dust Division 1 Division 2 Listed in NEC 500-3(c)

    Gas Grouping

    Typical gas hazard IEC 60079-0 Cenelec EN50014 North AmericaNEC Article 500 (Class I)* Minimum ignition energy (microjoules)
    Acetylene IIC A 20
    Hydrogen IIC B 20
    Ethylene IIB C 60
    Propane IIA D 180

    Simple Apparatus

    Passive components
    Well defined sources of stored
    energy considered in safety analysis
    Source of generated energy not more
    than * 1.5V, 100mA & 25mW


    Piezoelectric crystal
    protected components
    voltage or current enhancement

    * Note: North America still uses 1.2V and 20 microjoules

    Temperature Classification

    Surface area T4 Classification
    < 20mm 2 Surface temperature ? 275 °C
    ? 20mm 2 < 10cm 2 Surface temperature ? 200 °C
    ? 20mm 2 Power dissipation ? 1.3 W *

    * Reduced to 1.2W with 60°C ambient or 1.0W with 80°C ambient

    Enclosure Ratings

    NEMA, UL & CSA type rating Approximate IEC/IP classification

    Abbreviated protection description

    1 IP30

    Indoor, from contact with contents

    2 IP31

    Indoor, limited, from dirt and water

    3 IP64

    Outdoor, from rain, sleet, windblown dust and ice damage

    3R IP32

    Outdoor, from rain, sleet and ice damage

    4 IP66

    Indoor and outdoor, from windblown dust, rain splashing and hose directed water and ice damage

    4X IP66

    Indoor and outdoor, from windblown dust, rain splashing and hose directed water and ice damage

    6 IP67

    Indoor and outdoor, from hose directed water, water entry during submersion and ice damage

    12 IP55

    Indoor, from dust , falling dirt and dripping non-corrosive liquids

    13 IP65

    Indoor, from dust, spraying water, oil and non-corrosive liquids

    Certification Code

    * Located in non-hazardous area and maybe connected to hazardous area
    ** Hazardous area apparatus

    IP Codes


    First numeral
    Protection against solid bodies
        Second numeral
    Protection against liquid
    No protection 0 0 No protection
    Objects greater then 50mm 1 1 Vertically dripping water
    Objects greater then 12mm 2 2 Angled dripping water -75° to 90°
    Objects greater then 2.5mm 3 3 Sprayed water
    Objects greater then 1.0mm 4 4 Splashed water
    Dust protected 5 5 Water jets
    Dust tight 6 6 Heavy seas
        7 Effects of immersion
        8 Indefinite immersion

    Example: IP65
    equipment is dust-tight and protected against water jets