1. For sampling from transformer, oil switch or other electrical equipment, the samples shall be taken from the lower part of the valves. Before sampling, use a clean cotton yarn or cloth to clean the oil valve, then drain oil for rinsing it again.
2. For the casing to be sampled, when power is outage for repairing, the samples shall be taken from the sampling hole.
3. For the electric equipment without oil drain tube or sampling valve, the samples can be taken during power failure or maintenance.(zjl)