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Ranco Auto Cut OFF

General Description
The L Series, L7, LM7 and LM8, is a family of fixed setting temperature limit controls whose design is failsafe. The L7 is auto reset, whilst LM7 and LM8 are manual reset. The operating temperatures are factory set and non-adjustable by the customer. Settings are available between 50 and 160ºC with capillary length from 450-2000mm (1000mm standard). The L7/LM7 are SPST (single pole singlethrow) and LM8 is DPST (double pole single throw)


  • Element
  • Auto or manual reset
  • Fail-safe (cut-out to safety)
  • 16(3)A 400V ~. For LM8 ratings apply to each pole
  • Variety of settings and capillary options
  • Narrow profile to fit applications where space is limited
  • Versions available for Class I and Class II appliances
  • Versions for millivolt circuits (L7/LM7 only) available
  • Simple mounting

These controls are used on any application where protection
against overheat is required. Typical applications are:-

  • ‘Boil dry’ protection for waterheaters, washing machines,
    dishwashers, vending machines (protection of heating
  • High temperature cut-out on central heating boilers
  • Blocked flue sensor on boilers with natural draft (on
    operation the gas supply to the burner is switched off)
  • Protection against overheating in panel/convector heaters
  • Overheat safety for AC cassette units equipped with an
    electric boost heater
  • Overheat safety on compressor discharge pipes


Electrical Rating: L7/LM7: 16A 400V~resistive
3A 400V~inductive
LM8: ratings apply to each pole
Switch: SPST break on rise of temperature
DPST (LM8) break on rise of temperature
(note: for millivolt application L7/LM7 can be supplied with goldplated contacts)
Terminals: Tab 6,3mm
Terminal Configuration: As shown, earth terminals available if required
Approvals: Approved throughout Europe
Special versions approved for North America (see chart)
Maximum Head
At least 15ºC below sensed temperature, max 90ºC

Ranco Auto Cut OFF (2/3)

Temperature Range:   Fixed settings between 50ºC and 160ºC to order (factory set)
Tolerances: Standard ±8ºK on models with-out temperature, 50 - 115ºC ±3ºK is available
Capillary Length: 450 and 2000mm(in accordance to customer specification)
Capillary Insulation: Available on request

Ranco Auto-Cutoff  (3/3)

Capillary Form: Straight or coiled (minimum diameter 6mm) Approximately 400mm of capillary or the complete sensing
element is required for optimum sensing
Cross Ambient: Cross ambient versions with solid bulbs are available (LM7 and LM8 only). Temperature range 50 - 130°C.
The following information should be supplied with every enquiry:

  • Application
  • Model L7, LM7 or LM8
  • Setting required
  • Capillary length and sensing element (for options see Fig.3)
  • Control switch temperature
  • Mounting requirement (for options see Fig.2)

Barometric Effect
The control is calibrated to cut-out within the specified tolerance at a barometric pressure of 760mm Hg. For pressure higher (or lower) than this add (or subtract) 1°C for every 25mm Hg change.

This control must be applied and installed in line with local approvals and practices. Suitable earthing must be made by
appliance manufacturer and installer.

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