Disconnect Selection

[The Plc Kid]

I need to select an outdoor disconnect for a 200 amp service. This will be powering a backup air compressor. My question is on the difference between nema 3r and nema 4x. Some info i have found says riantight and some says rain resistant is this the same thing?

Which would be best 3r or 4x? would 3r be code compliant?

This will be mounted to the outside of the buildings wall nothing covering it no building eave or overhang.

 

[barbeer]

If not mistaken- 4x will be substantially more expensive than 3r. unless the environment is corrosive, use 3r.

 

[barbeer]

p.s. welcome to the forum.

 

[Cow]

Double check the disco to make sure the HP rating is high enough for the air compressor.

 

[jim dungar]

Briefly,
NEMA 4X enclosure are tested with a directed stream of pressurized water. The water may not enter the enclosure. These enclosures also contain gasketing, so they are dust resistant. Also they are corrosion resistant, that is the X in the type number.

NEMA 3R enclosures are tested with falling wind blown water. Water may enter the enclosure but it must not contact energized parts. The water must have a method of draining out. These enclosures are rated for exposure to sunlight. Gasketing is not required for a 3R rating.

For most outdoor appliactions I am satified with a NEMA 3R rating, although I prefer a NEMA 3R/12 when I can get them (these have gasketing to reduce dust entry)

 

[hershey]

4X is gonna cost ya big bucks. If your not installing it in something like a car wash area stick with the 3r

 

[jdsmith]

4X is gonna cost ya big bucks. If your not installing it in something like a car wash area stick with the 3r

The main thing that makes 4X so expansive is the stainless. See if you can get a NEMA 4 enclosure - same gasketing, but painted steel instead of stainless makes it much cheaper.

 

[jim dungar]

The main thing that makes 4X so expansive is the stainless. See if you can get a NEMA 4 enclosure - same gasketing, but painted steel instead of stainless makes it much cheaper.

NEMA4X must be corrosion resistant but not necessarily stainless steel, other materials include fiberglass and PVC.

 

[petersonra]

NEMA4X must be corrosion resistant but not necessarily stainless steel, other materials include fiberglass and PVC.

I think there are even some painted steel enclosures that are rated 4X.

Unless you have pressurized water or other liquids flowing onto the enclosure i would say 3R is adequate.

 

[jdsmith]

I think there are even some painted steel enclosures that are rated 4X.

Unless you have pressurized water or other liquids flowing onto the enclosure i would say 3R is adequate.

I've seen powder coated enclosures pass for 4X, not sure about painted.

NEMA4X must be corrosion resistant but not necessarily stainless steel, other materials include fiberglass and PVC.

Our specs at the plant prohibit fiberglass and PVC enclosures - I need to keep in mind that not everyone is in an industrial plant with a 4" stack of electrical specs and established material standards.

 

[jim dungar]

Our specs at the plant prohibit fiberglass and PVC enclosures - I need to keep in mind that not everyone is in an industrial plant with a 4" stack of electrical specs and established material standards.

I know of many industrial facilities that readily accept fiberglass and PVC enclosures.