We are asked with increasing regularity why a contractor can’t just use any old air compressor for a dry pipe sprinkler system. This is an issue we have covered thoroughly in our article “Do Not Use Retail Air Compressors for Fire Protection Applications” but there is a piece that we are often asked about that was not properly addressed in that article.
Why don’t General Air Products’ air compressors come with a plug or plug option like a retail air compressor?
First off, our air compressors are unlike retail air compressors in a variety of ways – our air compressors are fire protection air compressors and there's are not. Again refer to the previous article on this subject for a more thorough answer. Directly to the plug issue our response is this:
Cords and plugs must not be used for the connection of any air compressor being used in a dry pipe sprinkler application.
We have always stated that our units must be installed in accordance with national, state and local codes. Cords that are found on retail air compressors are designed for use with what NEC refers to as “portable motors”. An air compressor in use with a dry pipe sprinkler system is not a portable device, in fact they are categorized in code as “permanently installed devices”.
As “permanently installed devices” they are governed by the requirements set out in Article 430(.101 - .113) in the NEC. In order to comply with those requirements an air compressor in a dry pipe system needs to (among other things):
1.) Be on an individual dedicated circuit
2.) Be hard wired - which very specifically means no cords
3.) Have the correct disconnecting means (different for 115v and 230v)
4.) Have overload protection
5.) Be connected to a listed motor-circuit switch rated for horsepower
In practical terms the reason the compressor must be hard wired is simple – this is a life safety system, no device on a life safety system should be in a position to be inadvertently disconnected by simply unplugging it (or by flipping a light switch for that matter).
Remember, the air compressor is the heart of a dry pipe sprinkler system. If it is unplugged essentially the entire system is shut down.
If you have any questions or comments on this issue please contact us through the comments section below, or by calling or emailing us. If you have any pictures of an installation where the compressor governing a dry pipe sprinkler system is plugged in please send them to me – I’ll post them here and send you some General Air swag!