We just moved to a new place and are having issues with the electic in the barn. There are 3 tank heaters and in the breakers keep tripping.  Help! 

How old is the barn and breaker box? It might just need new breakers. Also check the size of your extension cords, you could be using too small of one for whats needed.

Haw big are the heaters.  Are they all on the same breaker?

You’ve got a short somewhere or the breakers are not the appropriate amp size for the heaters.  You need to make sure you have the proper gauge wire before you up breakers by too much or you could burn up the wire without tripping the breaker.

If the wiring is old it may be worth replacing for piece of mind.  We have romex we put up a few years ago to get lights going and I want to go back through and pull wire in conduit and change the breakers that things are on to clean it up more.

Pulling too much from one breaker.  use different plug ins on different breakers.  Also depends on size of tank heaters.  Some are 750 watt others are 1500 for colder areas.  Also make sure you get the heavy duty, for contruction sites, extention cords, I've already had one melt because I needed it in a pinch.  After this winter, I have all new wiring plans for our barn!  We have 5 tank heaters and 6 stall buckets.  I've spent more in extention cords to get everything on different breakers then I care to admit.  But sure saved time breaking ice and piece of mind knowing everyone has water.

Depending on how old the breaker box is and breakers, the breaker can go bad and once tripped, easy to do again.