normal "safety margins" on components used to be 20% as a rule of thumb. in other words, if a transistor is rated at 250V, it would be used in a circuit where the maximum voltage across the transistor would be 200V or less. now with far east companies trying to squeeze every penny out of products, the safety margins have become smaller, often between zero and 10%. this has the immediate effect of lowering production costs, but also makes the products less reliable, resulting in a higher percentage of in-warranty failures. unfortunately, for some reason, the bean counters never factor in the warranty failures and their repair costs, but only see the increased profits on the front end as a result of lower cost, and on the back end when people just throw away the failed product and buy a new one.