Standards:

IEC51, IEC61010-1,  BS89, NE60051, DIN43780

Cases:

Temperature influence:

All cases at least dust and splash water-proof.
All cases are made of strengthened self-extingushing PPO 
With a high hit-resistance and a maximum electric isolation

All instruments operate trouble-free at room temperature ranging from -25 to + 40.
The Max. Voltage to earth Voltmeter-The upper range voltage (full scale deflention)
Ammeter-The Voltage of the main power supply.
The meter used shall be keep cleaning. The user shall be made aware that, if the meter is used in a manner not specified by the manufacturer, the protection provided by the meter may be impaired.

Accuracy class:

AC, DC Voltmeters and Ammeters comply with the accuracy class 1.5.
The power meters comply with accuracy class 1.5.
The frequency meters comply with accuracy class1.0.
The maximum-demand meters comply with accuracy class 3.0.
The power factor meters and synchroscope meter comply with accuracy class 2.5.

Insulation test:

Mounting angle:

The insulation test is carried out at a voltage of 2KV, 50Hz 1 min and applies for instruments with the full scale deflection up to 650V. Other standards comply with IEC61010-1.

The instruments are calibrated for vertical mounting, unless other positions such as horizontal or inclined at any specified angle to the horizon. can be provided upon request (in this case, specify angle of inclination, please) The accuracy class refers to the specified mounting angle only.