If it only flickers when it is powered, first two things to check is the bulb and the ballast. Those bulbs do not last forever. Change the power sucker out for a LED. You will see your electrical bill drop ten fold.
http://www.ledsmagazine.com/ugc/iif...-175w-mercury-vapor-exterior-barn-lights.html
Retrofit guide. http://www.myledlightingguide.com/ledretrofit.aspx
They call the replacements "Corn Cob Bulbs". Check with your local electrical warehouse if they have them as a stock item, or can get it cheaper than you can find on amazon.com.
http://www.ledsmagazine.com/ugc/iif...-175w-mercury-vapor-exterior-barn-lights.html
Retrofit guide. http://www.myledlightingguide.com/ledretrofit.aspx
They call the replacements "Corn Cob Bulbs". Check with your local electrical warehouse if they have them as a stock item, or can get it cheaper than you can find on amazon.com.