It's too much when you find it too bright, or it fogs your paper - whichever comes first. To see how long you have before your paper gets fogged, do a proper safelight test.

Here are some things which may help:

Darkroom Design
http://www.kodak.com/global/en/profe...bs/ak3/ak3.pdf

Safelights and Testing

For a proper test procedure see "Testing Your Safelight Conditions" at the bottom of the main page:

http://www.kodak.com/global/en/consu.../k4Facts.shtml