PLEASE CAN YOU TELL ME THE BEST STANDARD TO USE IN DESIGNING INSTRUMENT , CONTROL AND ELECTRICAL PROJECTS ,AND CAN I USE DIFFERENT STANDERD IN THE SAME PROJECT,
Secondly, it depends on what you are designing. There are specific standards for all electrical devices, so you need to identify into which group your product falls. It may in fact be covered by more than one major standard. Then, each of those standards will reference a number of more fundamental standards - such as grounding, flameproofness, conduit size, etc.
On the international stage, the IEC and ISO standards are the ones to use. Nationally, each country has it's own set, but they are all moving towards adopting the IEC/ISO versions.
THE BEST STANDARD 
Re: THE BEST STANDARD
