Continuous and Intermittent Load

Yes.

NFPA

British standards

Indian Standard.

Look them up on the web.

If you are the end-user and cost is not going to be an issue for you, then use your lifetime as your basis. Order the transformer specifications based on your expected usable life at 100% duty cycle!

Considering all manufacturing overheads, manufacturers being a business normally will base it on anticipated profit margins and expected ROIs on the product. Whether we like it or not, the sooner they realize the ROIs the better for the business!

Generally, if you do some research while shopping around for any product, most of the time you will find that its cost will be directly proportional to the quality of the product!

Normally, in designing electrical system, I consider all type of load (continuous, intermittent and stand by) in calculate the optimal capacity for transformer. There are multiplier factor for each type of laod, continuous loads always multiply with 1, intermittent load multiply with 0.5 and stand by load multiply with 0.1 (depend on the system). Sum from all above will be consider for transformer capacity. Hope it help.

I'd just add that there's no need to consider time to reach thermal equilibrium. Total power drawn is only an estimate and uncertainty in that is much greater than any difference made by cold vs hot motor.

Are you a consultant or end user ? Arriving at capital equipment rating capacity is both an art and science. You will have to factor in not only the load details but other allied inputs like, ambient temperature, height of installation, future expansion (Immediate short term & long term), kind of loads(linear or nonlinear), type of cooling, free field or enclosed installation etc. Site centric inputs ( operation cycle, process or non process industry ) also needs to be considered in the design. Please do not be singularly focussed on what the books say but be judicious in its application. If you are novice, consult your seniors at site who will give you additional insights (sometimes only if you ask specifically ).

My question is not for sizing consideration of transformer as some contributor has suggested. I wanted to know which loads are to be considered as continuous and which one are as intermittent.

Then ask your mechanical engineer and process engineer. Normally it come from them.

You cannot classify each and every equipment as continuous duty or intermittent duty etc. A motor can be used to run continuously in a process industry and the same motor in another application can be used in start & stop mode.Even in lighting you will have general lighting (base lighting) and Task lighting (continuous). However equipment's will have its designed duty cycle for which you will have to refer to its manufacturer. This will determine whether it will suit the desired application. It is all in the location and application.

There's no way anybody on a forum like this can tell you. It depends on the application.

Duty cycles are part of the design considerations for any equipment before it is produced and marketed. Proper product applications are normally limited by such guaranteed duty cycles.

Part of equipment planning is where the designed system of operations are incorporated. System and equipment specifications are developed according to the designed system and its intended applications. Device are selected based on the developed equipment or product specifications to meet and satisfy the proper operations of the designed systems. Depending on the magnitude of the project, bids were either put out to pre-selected vendors or pre-ordered directly from manufacturers.

The answers to your questions about which load or equipment were already answered by the Equipment Planners.. They are contained among the list of equipment specifications!