Certainly not too simple a question for this forum. 

The Service Contract Labor Standards statute does not apply to any contract for for public utility services, see FAR 22.1003-3(e).  I won't go into a detailed description, but one of the reasons for FAR part 41 is because of the unique nature of procuring utilities.  In most cases your only contracting for the utilities (e.g. electricity, natural gas, etc.) themselves but there is a lot of service activities associated with the production and delivery of the utility.  These are typically already regulated by both federal and state governments.