How is it that CLT can be used for around 8 light bulbs? I have been given the following problem.
The light bulbs available have an average lifetime of 1000 hours with a standard deviation of 50 hours. How many light bulbs should we stock so that we can be sure to keep the light on for at least 7200 hours with a probability of at least 98% ?
The answer is given as

How is it OK to invoke CLT here? I thought we needed a sample of over 30 or a normal distribution.

No, you don't need exactly N=30 for the normal approximation to be somewhat good. It can be more, or less, good depending how skewed or platy- or lepto-kurtic the data are. However, I think it's valid to claim that we don't have specifics about how good "somewhat good" would be for an approximation in this case. Alas this seems to be one of the homework questions where you're just supposed to use the methods you know, and not read ahead too much, and because there's no other answer with the limited premise.
