I had 2 bulbs fail while I was out of town and my bator was 93 when I got home. I had eggs at 7 days and at 15 days. I have had this happen in the night before and correct in the morning and still have a normal hatch. I dont know how long these were that low and am wondering how long was too long. I had 108 total and 48 that I drove 60 miles to get.