Remote I/O

cdcabrera

Member
Location
Riverside, CA
I am doing a system layout and have come to a bit of a snag, looking for some input as there is possibly something I have over looked.

Multiple skids in a C1D2 area with remote I/O. Main UCP is in an unclassified area.

Remote I/O will only have fiber optic and 10 amp 24v power interconnection to UCP. All components in the remote I/O panels are C1D2 rated except the main breaker.

The snag is appropriate circuit protection/power disconnect at the remote I/O stations. Normally I would use a breaker and purge, but customer mentioned I may not have purge gas available so I am trying to find an appropriate means of power disconnect locally. I have not found a breaker rated for C1D2 which is leading me to believe that they dont exist and if they do, it will be cost prohibitive for this project.

Having the breaker in the UCP with a power disconnect switch on the panel door is an option, but I am not a fan of having the breaker remote. I could mount an explosion proof breaker box next to the the box that feeds the remote I/O panel. There is a Stahl breaker that I found but all of its certs are ATEX, IECEx so i will have to do some research on how that translates to the class div ratings.

Any thoughts?
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
There are no circuit breakers directly rated for Class I, Division 2. There are several applicable protection techniques though. See Section 501.115(B)(1).

There is a Stahl breaker that I found but all of its certs are ATEX, IECEx so i will have to do some research on how that translates to the class div ratings.​
There is no translation if they only have ATEX. IECEx ratings. They must have an AEx rating. See Section 505.9(C)(2)(3). ATEX means nothing at all in the NEC.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
A power supply listed as class 2 requires no ocpd on the dc side as they are self protected. Run 115v to the rio box with the ocpd in an unclassified area and put a hermetically sealed switch at the rio box to disconnect if you feel the need.
 

cdcabrera

Member
Location
Riverside, CA
A power supply listed as class 2 requires no ocpd on the dc side as they are self protected. Run 115v to the rio box with the ocpd in an unclassified area and put a hermetically sealed switch at the rio box to disconnect if you feel the need.
i would prefer not to run 120v but that is an option i hadnt considered.

is it poor operational practice to have the ocpd in a remote location? i have plenty of room in the UCP to make that happen and can figure out an isolation method at the panel itself.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
noted, so the since the data sheet says the markings are as following, with no mention of an AEx rating i am out of luck
As I said earlier, ATEX and IEC Ex are meaningless in the NEC. (BTW, "AEx" just means it has been certified by a US NRTL)

I already cited Section 501.115(B)(1) as applicable.

A remote OCPD is acceptable [Section 409.21] but, depending on your applicable worker safety regulations, [NFPA 70E or California Title 8 for example] you may still need a local disconnecting means, which is a general requirement not specific to hazardous locations.

If you really want to stick your neck out with ATEX or IEC Ex ratings. you might consider Section 500.8(A)(3).​
 
The ETA ESX10 series is an electronic Circuit protector that is rated for Class I Division 2, A,B,C,D locations. it is also UL 508 approved.

We have been using these and primary breakers in Remote control panel 24 VDC circuits for equipment such as PLC, RIO, Ethernet Switches and circuit protection. Since they also have a manual trip function, we have been using them ahead of meter and instrumentation fuses as the "proceeding switch complying with 501.105(B)(2).

Phoenix has also released a series of Class I Division 2 circuit breakers recently. These are actually dual rated at 50 VDC and 120 VAC.
So either the ESX10-TA-100-DC24V-10A or the Phoenix HMC 11 120AC 10A C1D2 - 2907196 might be suitable for your needs.
A simple factory sealed snap switch mounted beside the panel can provide a local disconnect for the panel if required.
 

samuelt83

Member
Location
Houston TX
Occupation
Electrical Engineering
AIRPAX AP or UP circuit breakers are hermetically sealed and are Listed for C1D2 use. The Phoenix HMC 11 120AC 10A C1D2 probably is just a repackaged AIRPAX or other hermetically sealed breaker.
 

samuelt83

Member
Location
Houston TX
Occupation
Electrical Engineering
From the FM Approval Guide only the single pole AIRPAX UP1 version will have C1D2 markings:
"
UP1

UP1-1-a-b-FM, UP1-1-a-b-FMAX. Circuit Breaker.
FM16US0204U

NI / I / 2 / ABCD / T6 Ta = 65°C (Models rated 10A and below)
NI / I / 2 / ABCD / T4A Ta = 65°C (Models rated above 10A up to 20A)
I/2/ AEx nA nC/IIC /T6 Ta = 65°C (Models rated 10A and below)
I/2/ AEx nA nC/IIC /T4 Ta = 65°C (Models rated above 10A up to 20A)

a = Frequency and delay 40, 41, 42, 41F, 42F, 50, 51, 52, 51F, 52F, 60, 61, 62, 64, 65, 61F, 62F, 64F, 65F, 71, 72, 79, 71F, 72F or 79F.
b = Current rating (051, 101, 201, 251, 401, 601, 751, 102, 1251, 1751, 202, 252, 302, 502, 702, 802, 103, 123, 153, 173, 203).
Special Conditions of Use:
1. Shall be installed in compliance with the enclosure, mounting, spacing and segregation requirements of the ultimate application, including access only by use of a tool.
2. It shall be ensured that the circuit breaker is electrically bonded to the protective earthing terminal of the final equipment.
3. The connection between the protective earth terminal and the accessible conductive parts shall be capable of carrying 25 Amps d.c or a.c. rms for one minute.
4. Modules shall be installed in an enclosure which maintains an ingress protection rating of IP54.
"


CRI also repackages the AIRPAX breaker in a DIN Rail housing, CoC here.
 
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