Weatherproof Electrical Boxes

A weatherproof box is a gasketed electrical box rated to mount outdoors and keep water away from the wiring, receptacle, or switch inside. It comes in cast metal styles like FS and FD boxes, nonmetallic PVC, and Bell-type outlet boxes, in one- and two-gang sizes. Each has threaded hubs or knockouts for conduit and pairs with a weatherproof or in-use cover. Lumera Electric carries FS, FD, Bell, and PVC weatherproof boxes for exterior wiring.

Weatherproof Electrical Boxes

What's the difference between FS and FD weatherproof boxes?

Both are cast device boxes; the depth differs. An FS box is shallow (about 2 inches deep), used where the wall cavity or surface is tight. An FD box is deep (about 2.7 inches), giving more room for conductors and devices. Both mount on the surface with threaded hubs for rigid or IMC conduit. Pick FD when wire fill is heavy.

What is a Bell box, and when do I use one?

A Bell box is the round or rectangular outlet box you see on house exteriors. It's a nonmetallic or die-cast box with three or more threaded holes, sealed with plugs you remove only where conduit enters. Use it for a surface-mounted outdoor receptacle or light on siding, brick, or a post. It pairs directly with a weatherproof or in-use cover.

How do I choose the number and size of hubs (entries)?

Count your conduit runs first. A box with one or two hubs suits a simple drop; a three- or four-hub box lets conduit pass through or branch. Hubs are threaded for 1/2-inch or 3/4-inch conduit to match your raceway. Leave unused hubs sealed with their closure plugs to keep the box weatherproof.

Should the box be metal or PVC for outdoors?

Both work outdoors; the deciding factor is the conduit system. A cast aluminum box matches metal conduit (rigid, IMC, EMT) and resists impact. A PVC box matches nonmetallic conduit and won't corrode in coastal or chemical settings. Keep the box and conduit material the same so the threaded hubs and bonding line up correctly.

What makes a box NEMA 3R or weatherproof?

NEMA 3R means the box sheds rain. The rating certifies the enclosure resists rain, sleet, and ice formation on the outside. A weatherproof box adds a gasket and sealed hubs so no water reaches the device. For washdown or submersion, step up to NEMA 4 or 4X. Match the rating to the exposure the box will face.

Finishing the outdoor box? The covers that seal these are in Weatherproof Covers, the spacers that add depth in Weatherproof Extension Rings, and the conduit and connectors feeding them in Conduit & Fittings.