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For EC&M Magazine
By Mike Holt, NEC® Consultant
Here's the follow-up to yesterday's newsletter.
This includes the answers to the questions sent, so you can see how you did.
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Figure 01
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Figure 01
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For EC&M Magazine
By Mike Holt, NEC® Consultant
Here's the follow-up to yesterday's newsletter.
This includes the answers to the questions sent, so you can see how you did.
Note: The answers to these questions are based on the 2020 NEC.
Q1: What are the conditions FMC can be used and installed?
A1: 348.10 Uses Permitted
FMC is permitted to be installed exposed or concealed.
Q2: Under what conditions can FMC not be used and installed?
A2: 348.12 Uses Not Permitted
FMC is not permitted:
(1) In wet locations. Figure 01
(2) In hoistways, other than as permitted in 620.21(A)(1).
(3) In storage battery rooms.
(4) In any hazardous (classified) location, except as permitted by 501.10(B).
(5) Exposed to material having a deteriorating effect on the installed conductors.
(6) Underground or embedded in poured concrete.
(7) Where subject to physical damage.
Q3: What is the minimum and maximum FMC trade size permitted?
A3: 348.20 Trade Size
(A) Minimum. Trade size ½, except trade size 3⁄8 is permitted for the following applications:
(1) For enclosing the leads of motors.
(2) Not exceeding 6 ft in length:
a. For utilization equipment,
b. As part of a listed assembly, or
c. For luminaire tap connections in accordance with 410.117(C).
(B) Maximum. Trade size 4.
Q4: What are the requirements for securing and supporting FMC?
A4: 348.30 Securing and Supporting
(A) Securely Fastened. FMC must be securely fastened by a means approved by the authority having jurisdiction within 1 ft of termination, and it must be secured and supported at intervals not exceeding 4½ ft.
Where cable ties are to be used to secure and support Type FMC, they must be listed and identified for securing and supporting.
Ex 1: Type FMC is not required to be securely fastened or supported where fished between access points through concealed spaces and supporting is impractical.
Ex 2: If flexibility is necessary after installation, unsecured lengths from the last point the raceway is securely fastened are not permitted to exceed:
(1) 3 ft for trade sizes ½ through 1¼
(2) 4 ft for trade sizes 1½ through 2
(3) 5 ft for trade sizes 2½ and larger
Ex 4: Lengths not exceeding 6 ft from the last point where the raceway is securely fastened can be unsecured within an accessible ceiling for a luminaire(s) or other equipment. Listed fittings are considered a means of securement and support.
(B) Horizontal Runs. FMC installed horizontally in bored or punched holes in wood or metal framing members, or notches in wooden members, at intervals not more than 4½ ft is considered supported, but the raceway must be secured within 1 ft of terminations.
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