Quoting from the Wikipedia article on the Solar Storm of 1859;
On September 1–2, 1859, the largest recorded geomagnetic storm occurred. Aurorae were seen around the world, those in the northern hemisphere even as far south as the Caribbean; those over the Rocky Mountains were so bright that their glow awoke gold miners, who began preparing breakfast because they thought it was morning. People who happened to be awake in the northeastern US could read a newspaper by the aurora's light. The aurora was visible as far from the poles as Cuba and Hawaii.
So, it didn't quite make it to the equator, but it came very close. There is no physical reason why you can't get aurora at the equator, but it takes a lot of very energetic particles being ejected by the sun over a brief period.
However, as I mentioned in my comment, a solar storm of that magnitude would wipe out most of the Earth's electric grids. Even the telegraph systems of the 1800's couldn't survive. Another quote from the Wikipedia article;
Telegraph systems all over Europe and North America failed, in some cases giving telegraph operators electric shocks. Telegraph pylons threw sparks. Some telegraph systems continued to send and receive messages despite having been disconnected from their power supplies.