Most companies wont allow you to hard wire one in. The ones that allow invertors generally only allow the ones that plug into a cigarette lighter socket. A lot of companies dont allow them in their trucks under any circumstances and will fire you if one is found. Very very few will allow you to hard wire one of the big invertors in the truck. Most wont list this on their sites so that is really a question to be asking the recruiters,it varies from company to company and these kind of policeis have been known to change without much warning so your best bet is to check with the companies you are interested in.
Roehl allowed inverters up to 2500 watts in their tractors. Both the smaller cirarette lighter plug in types and larger hard wired types. The only catch was that the larger hard wired types had to be installed by their maintenance dept, and removed by them when turning your truck in.
Of course they charged the driver an installation fee for the hard wired types, but also assumed responsibility. They worried about improper installs by the driver causing an electrical short or worse a fire.
