| a. Standard Ambient. | |
| When the term "standard ambient" is specified in the Methods of this standard, use the values shown below. If the term is not used and no specific values are called for in the test Method or the materiel specification, conduct item tests (e.g., pre-, during, and post-test) at standard ambient conditions. | |
| Temperature: | 25° ± 10°C (77 ± 18°F) |
| Relative humidity: | 20 to 80 percent |
| Atmospheric pressure: | Site pressure |
| b. Controlled ambient. | |
| When the ambient conditions must be closely controlled, maintain the following: | |
| Temperature: | 23° ± 2°C (73 ± 3.6°F) |
| Relative humidity: | 50 percent ± 5 percent |
| Atmospheric pressure: | 96.45 +6.6 / -10.0 kPa 28.5 +2.0 / -3.0 in Hg |
- c. Input power.
If the test item requires electrical input power to function, one should consider the normal operational input voltage range (steady state) specified from the power source (generator, transformer rectifier, and alternator/battery) that would be encountered in use. On military aircraft and ground vehicles, these voltage ranges can be found in MIL-STD-704A-F and MIL-STD-1275A-D. On military shipboard mounted equipment, the voltage ranges can be found in MIL-STD-1399, section 300. Commercial aircraft ranges can normally be found in RTCA DO-160, section 16, power input. Commercial ground equipment input power is normally obtained from building utilities. Identify and use commercial standard voltage ranges for these test items. Use of other applicable documents may be required as needed. In addition to nominal voltage, operation at the upper and lower thresholds should be considered. Electrical and power characteristics for aircraft and ground vehicles can be found in Method 520, however it is highly recommended these values are cross referenced with the aforementioned Military Standards to ensure the most current values are utilized.
An electrical survey may be required if there is a potential voltage, frequency, crest factor, ripple, phase displacement, or distortion issue that could lead to test item failure and/or safety of personnel.
NOTE: Every effort has been made to use metric units throughout this document. The initial figures are followed by US units in parentheses, but these conversions are not usually repeated throughout this document.