Fuses in Hazardous Area

[ilan7]

Hi all
We need to use small fuses (1 to 6 Amp, 24 VDC) in Class I Zone 2 (Div. 2) hasardus area. After doing some research, found out that ceramic fuses conseder to be "None Sparking" and can be consider as fulfilling the NEC requirements. Wondered if anyone have more solid argument or another (better) simple solution.

 

[JLSeagull]

The NEC requirement in article 501.115 is for non-indicating, filled, current limiting fuses.

A publication from Cooper Bussmann that mentions several such fuses:
Class CC
LP-CC 1/2 through 30A
KTK-R 1/2 through 30A
FNQ-R 8/10 through 30A
KTN-R 1 through 600A
KTS-R 1 through 600A
LPN-RK_SP* 3 through 6.25 and 70 through 600A

Class T
JJN 1 through 1200A
JJS 1 through 800A

Class J
JKS 1 through 600A
LPJ_SP through 600A

Class G
SC 1/2 through 60A

Class RK5
FRN-R 3 through 7.25 and 225 through 600A
FRS-R** 65 through 600A after October 1997 or date code D40

Class L
KRP-C_SP 601 through 6000A
KTU 601 through 6000A
KLU 601 through 4000A

Medium Voltage
JCH-30
JCH 2R through 24R
JCG-30
JCG 2R through 24R

A Ferraz Shawmut publication lists the following products that meet the description of "non-indicating, filled, current limiting" as referenced in Section 501.115(b)(3) of the 2005 National Electrical Code. The table doesn't print with the columns. Use the Catalog number and go from there.

Cat. No. U.L. Class U.L. Standard Guide File
A2D(1/10- 7)R* RK1 248-12 JDDZ E2137
A2K(1- 600)R RK1 248-12 JDDZ E2137
A3T(1- 1200) T 248-15 JDDZ E2137
A4BT(601- 6000)* L 248-10 JDDZ E2137
A4BQ(601- 6000)* L 248-10 JDDZ E2137
A4BY(601- 6000) L 248-10 JDDZ E2137
A4J(1- 600) J 248-8 JDDZ E2137
A6D(1/10- 7)R* RK1 248-12 JDDZ E2137
A6K(1- 600)R RK1 248-12 JDDZ E2137
A6T(1- 800) T 248-15 JDDZ E2137
AG(3- 60)* G 248-5 JDDZ E2137
AJT(1- 7)* J 248-8 JDDZ E2137
ATDR(1/4- 30)* CC 248-4 JDDZ E2137
ATMR(2-1/2 - 30) CC 248-4 JDDZ E2137
ATQR(2- 30)* CC 248-4 JDDZ E2137
HSJ(1- 600) J 248-8 JDDZ E2137
HSRK(70- 600)R RK1 248-12 JDDZ E2137
TR(1/10- 7)R * RK5 248-12 JDDZ E2137
TRS(1/10- 7)R* RK5 248-12 JDDZ E2137

 

[JimCasey]

Your other choice is to use conventional fuses or circuit breakers inside of a Div II enclosure.

Class 1 Div II is >>essentally<< addressed by NEMA IV housings. Div II specifies that hazardous conditions are expected to be possible for just a few minutes per year. You can't use a a NEMA IV box unless the manufacturer has also certified it for Div II, but the gasketed cover ensures that in the short time hazardous conditions are possible, a LEL atmosphere will not be able to diffuse into the housing. Other requirements would be sealed conduit connections. Still, without a manufacturer's cert, you'd be misapplying the housing and assuming liability. CYA.

 

[JLSeagull]

The enclosures can be purged to accommodate the area classification. Whether using a purged enclosure, explosion-proof enclosure or fuses rated for a Class I Division 2 locations, the fuse terminals would not be suitable for removing fuses under power. Consider a note outside the enclosure advising to remove power before changing the fuse. Also if using the Division 2 fuse consider a note to only replace with "non-incicating, filled, current-limiting fuses rated for Class I Division 2 hazardous locations".