Contractors must never forget that they are primarily installers, not engineers. Design deficiencies and code concerns should be communicated to the electrical engineer immediately. The specifications may require that all questions be sent to the project architect. It is always best to put concerns in writing.
When reading the specifications and drawings be sure that you understand exactly what is being said. Do not interpret it to mean something other than what is said. If there is any doubt to the intent of the specifications or drawings, seek clarification.
If there are conflicts in the project’s drawings and specifications that place the contractor at a disadvantage, any concerns should be brought to the attention of the architect. It is not the responsibility of the contractor to correct design flaws in the contract documents. Properly addressing design concerns will keep the playing field level for all contractors.
Most drawings have a block similar to this one.
The contractor must be very careful about taking ownership of a design. Some states may require a Professional Engineer to perform the design.
Remember, estimating is expensive, poor estimating is costly, but quality estimating is profitable.