The arc flash duration is normally determined from the protective device's time-current curves (TCC's). This approach assumes the device has been maintained and will operate according to the TCC. Most people realize this might be optimistic at best and therefore arc flash studies are usually accompanied by at least one of the following:

>A legal disclaimer stating that it is assumed the protective devices have been properly maintained and will operate according to their published TCC.

>Testing the protective devices and taking necessary corrective action

Here is this week's question:

Which of the following are included in the study to account for poor device maintenance?

(1) Legal disclaimer
(2) Device Testing and Maintenance
(3) None of the Above/Something Else

Select all that apply

Here is a question for a philosophical debate:

If a study has a disclaimer about the data, the condition of the equipment etc. and the utility usually has a disclaimer about their data being based on specific conditions that may change etc. then how much faith do we put into the results of an arc flash study?

It seems that many interpret a study as being an exact science when a) the calculations are approximate from what I understand and b) everything seems to have a disclaimer implying it might not be correct or could change.

This does not provide a comforting feeling when you view it this way.