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Design Standards

square bullet ELECTRICAL STANDARDS (continued - page 2 of 2)

Equipment and Materials:

  • Listed as defined in NEC Article 100 for application
  • Conduit - see table below for environment and use

ENVIRONMENT

RACEWAY

BOXES, ENCLOSURES, CABINETS

Dry locations, concealed

RMC, IMC, EMT, RNC, ENT1, FMC, LFMC, LFNC, WW

SM, FS/FD, NM, NEMA 1

Exposed, subject to damage

RMC, IMC

SM, FS/FD, NM, NEMA 1

Exposed, not subject to damage

RMC, IMC, EMT, RNC, ENT2, FMC, LFMC, LFNC

SM, FS/FD, NM, NEMA 1

Wet locations, subject to damage

RMC3, IMC3, EMT3, WW7

FS/FD, NEMA 4, 4X

Wet locations, not subject to damage

RMC3, IMC3, EMT3, RNC, ENT2, LFMC, LFNC, WW7

FS/FD, NM,
NEMA 4, 4X

Outdoor locations, exposed to rain, sleet, wind-blown dust, and external icing

RMC3, IMC3, EMT3, LFNC, WW7

FS/FD, NEMA 3,
3R, 3S

Submerged

RMC3, IMC3, RNC

NEMA 6, 6P

Embedded in concrete

RMC, IMC, EMT4, RNC, ENT4

FS/FD

Under concrete slab

RMC, IMC, EMT4

 

Underground, direct burial

RMC3, IMC3, EMT3, RNC, ENT, LFNC

 

Embedded burial

RMC, IMC, EMT4, RNC, ENT4, LFNC

 

Industrial location, general

RMC, IMC, EMT, RNC, FMC, LFMC, WW

FS/FD, SM,
NEMA 12, 12K

Subject to corrosion

RMC3, IMC3, EMT3, RNC, LFMC

NEMA 4X, 11

Subject to oil, vapors

RMC, IMC, LFMC

FS/FD, NEMA 13

Hazardous Class I, Division 18

RMC, IMC, FMC8

NEMA 7, 8

Hazardous Class I, Division 28

RMC, IMC, LFMC, FMC, WW5

FS/FD, NEMA 1, 7, 8, 12

Hazardous Class II, Division 18

RMC, IMC, LFMC, WW5

NEMA 9

Hazardous Class II, Division 28

RMC, IMC, LFMC, WW5

FS/FD, NEMA 1, 9, 12

Hazardous Class III8

RMC, IMC, LFMC, WW5

FS/FD, NEMA 12



TABLE LEGEND

TABLE NOTES

RMC - Rigid metal conduit
IMC - Intermediate metal conduit
EMT - Electrical metallic tubing
FMC - Flexible metal conduit
LFMC - Liquidtight flexible metal conduit
RNC - Rigid nonmetallic conduit
ENT - Electrical nonmetallic tubing
LFNC - Liquidtight flexible metal conduit
WW - Wireway
SM - Sheet metal box
FS/FD- Cast metal box
NM - Nonmetallic
NEMA - Re: NEMA 250 type classification

1 — Finishes must provide barrier with 15-minute rating.
2 — Building not more than 3 stories above grade.
3 — Corrosion protection required.
4 — With fittings for purpose.
5 — Enclosed and gasketed.
6 — Dusttight wireway only.
7 — Raintight wireway only.
8 — Suitable for hazardous location.

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