Builders will try to walk all over you. This is their technique in exerting control, giving you the impression that if you don't go along with their way, you won't work for them. If that's what you're buying into, you're not playing it smart. This is how you do it.
You set up a meeting, telling the builder you need to speak with him briefly and you will not take up too much of his time. You begin by praising the guy, saying how you know what a good builder he is and how much pride he takes in building a quality home. Then you say those are your goals too. And you want to provide him with the best work and service of anyone around. Then tell him to be able to do that, you need a few small things. Then you provide him with a brief written summary of the things that need to be done before you can install the flooring. Provide documentation from the distributor, the NWFA and the flooring manufacturer to show it's not you that's saying this but the flooring industry. Tell him he wouldn't want his framing crews to cut corners would he? Or the plumbers? Or the Electricians? He certainly must not want you to provide an inferior floor, would he? Of course not! Therefore, you both are in agreement that these items need to be addressed. Here's where you suggest ways of making that happen for him. Some people love to have their problems solved by someone else. Builders are no different. Find out how you can accomplish getting temp power to the furnace. We do it here in CA, about the most highly regulated state in the USA. So I'm am sure this can be done. Figure it out for your builder and you'll gain his respect and loyalty. If you act just like another whining sub, he'll loathe you.
So, man up and take charge. Remember, YOU are the hardwood flooring expert. The builder hired YOU to provide him with expert advise and service. If you have a defeatist attitude before exploring all options, then you have become your own worst enemy.
Now I'll get down from the soap box