在60598-2-4里要求，如果灯具15°翻转的话是要做热试验的。相关条款如下：
IEC 60598-2-4-1997 Portable general purposeluminaires
4.12Endurance tests and thermal tests
~~~~~~
In addition,for portble luminaires designed for standing on a floor or table which overturn when
places in their normal position of use on a plane inclined at an angle of 15°to the horizontal, the
test of 12.5.1of section 12 of IEC60598-1 is made with the luminaire on a horizontal surface, in the most unfavourable of the overturned positions that may reasonably be expected in practice.