Hi Roman,
It depends on the type of drawings and engineering you're doing. Basically, it's cut-up into 3 main areas: i) Electrical Engineering , ii) Mechanical Engineering , and iii) Civil Engineering. Of course, there are a lot of sub-areas of these three. For example, in Electrical/Electronics Engineering, the standards are somewhat different depending on whether you're designing Electric Power Transmission & Generation or instead, if you're designing AC to DC Electronic Power Supplies.
For you, it sounds like you would be doing mostly mechanical engineering. The ASME (American Society of Mechanical Engineers) is one of the best places to go. However, there are a lot of helpful links online on the web, just Google: U.S. Mechanical Drawing Standards (and I also recommend doing other searches with slightly different wording). For Electrical, the ANSI (American National Standards Institute) & IEEE (The Institue of Electrical & ELectronics Engineers) and the NEC (National Electrical Code). The NEC isn't so much for drawing as it is the U.S.'s Nationwide Legal Code for Design and Installation of Electrical Wiring, etc.
I hope that helps.
Kamran Kazem, V.P. & CTO
Magnetic Design Labs, Inc.
