Choosing The Correct NEMA Enclosure Size
NEMA enclosures exist in a wide range of sizes, from the small push button enclosures to panels that are full room sized. Choosing the correct enclosure size may seem as easy as measuring the layout of circuitry that will be placed inside it, but the question of whether full enclosure is absolutely necessary and maybe more is needed for cooling.
The first decision is to identify the equipment that needs protection from the environment, or indeed the equipment that may need protecting from each other. The simplest and most expensive way is to cover everything but that may not be necessary. Do parts of the equipment need different protection? Or are there parts that need none at all? Maybe some components need protection from the dust whilst others are fine exposed. It is all too common to overestimate that part and buy an enclosure that is just too big for what is needed. It may in the end come down to deciding in the cost of two smaller enclosures against the cost of one larger one, a purely budgetary decision. The important point is not to waste money by buying an enclosure that is too big.
Buying one that is too small to save on cost can be a problem too when budgetary constraints affect decisions too much. Keep a balance of costs, maybe more time and money will be spent on trying to fit the components into a smaller space just to save on cost of a Keleenclosure and in fact end up costing more at installation time.
One more consideration will be if any components are likely to be upgraded at any point. Upcoming technology affects what you will need to do within shorter terms and if you are maintaining a site for a long time this becomes more and more apparent. You need to take into account that components will need to be changed or even upgraded at certain intervals, and it is better to take that into account when sizing the enclosure surrounding them. The other important factor is not to make the installation difficult to put together, if a component needs to be changed later does the installer have enough room to move around it. The savings in the long term can be significant because you need only account for the component upgrade and not larger re-installations and new enclosures.
Another factor that will make the enclosure larger or need to be considered in locating the components within the installation, is cooling. For regular installations like switching equipment, the need for cooling may not be a concern but when a number of components are placed together in an enclosed space heat is readily output. The equipment may stay cool through natural convection, usually this takes place in exposed components that cool down from the air in the room but if enclosed then forced convection cooling might be necessary.
Room for the cool air inlet and hot air outlet need to be made in those circumstances and for the currents within the enclosure to flow. If there is not enough space for this or the inlets and outlets are not valid in the environment then room for a closed loop cooling system will be necessary. Conversely in very cold environments then possibly heating components may be needed, but that will be part of the installation design and the correct enclosure will account for that environment.
Although many of the points above are particular to certain kinds of installation it is worth considering which of these are particularly relevant. In the short term can be the usual over buying of enclosure, in the long term the problem of not thinking about later maintaining of the components, selecting the correct NEMA enclosure size should need to be done once only, on the first installation.