In many instances, moisture is detrimental to functioning of electrical or mechanical devices.Thousands of electrical relays may be threatened by pitting due to excessive arcing under high humidity conditions. Also, the presence of water vapor may corrode the contact points of infrequently operated electrical conductors resulting in poor closure of electrical circuits. In extreme cases, there may be no closure at all.

In other such places as radar stations and industrial applications, electronic equipment is also subject to loss of efficiency and high maintenance costs when exposed to humid conditions. And for work environments containing computers and other data processing
systems, humidity control is essential for assuring proper equipment function, Where practical, maintenance of dry enclosures may be necessary, Sometimes, it may be necessary to condition the equipment itself, since electrical operating devices are often enclosed in their own metal cases.