For Class I Division 1 hazardous locations, the National Electric Code says:
NEC 504.4 Equipment
All intrinsically safe apparatus and associated apparatus shall be listed.
Exception: Simple apparatus, as described on the control drawing, shall not be required to be listed.
The FOGRod comes under this exception because it clearly meets the NEC definition of simple apparatus:
NEC 504.2 Definitions
Simple Apparatus.
An electrical component or combination of components of simple construction with well defined electrical parameters that does not generate more than 1.5 volts, 100 milliamps, and 25 milliwatts, or a passive component that does not dissipate more than 1.3 watts and is compatible with the intrinsic safety of the circuit in which it is used.
Informational Note: The following apparatus are examples of simple apparatus:
(a) Passive components, for example, switches, junction boxes, resistance temperature devices, and simple semiconductor devices such as LEDs
(b) Sources of stored energy consisting of single components in simple circuits with well-defined parameters, for example, capacitors or inductors, whose values are considered when determining the overall safety of the system
(c) Sources of generated energy, for example, thermocouples and photocells, which do not generate more than 1.5 V, 100 mA, and 25 mW
Here is the relevant page from NEC with the key items highlighted:
How Can We Confirm that the FOGRod is a “Simple Apparatus”?
The FOGRod has no electronic components, no moving parts and no sensing circuits. The construction is simple. It consists of multi-core cable, with each core having a resistance less than 2 Ω and each core terminating in a metal contact. Therefore, the FOGRod is a passive component with very low resistance. Each core conducts less than 100 μA and so in total the FOGRod dissipates <1 mW.
Therefore, the FOGRod is defined by the NEC code as a Simple Apparatus and does not need to be listed by UL.
What IS Barriers have been Approved for the FOGRod & LIT?
Wastewater Level has tested two barriers and approved them:
– Pepperl & Fuchs: Z967
– R Stahl: 9002/77-220-146-001
Both of these are 2-channel barriers, so you need 6 in an installation (10-channels + 1 channel for the cable loopback test), however, their footprint is quite small – each barrier is about the size of a deck of playing cards.
We currently stock a set of P&F Z967 (qty 6) as our part number FOG-ISB (one FOG-ISB = 6x 2-channel barriers suitable for one LIT and one Fogrod or one LIT and multiple Fogrods).
See the Class I Division 1 Control Drawing 50022
What about Division 2?
The FOGRod connected to the LIT has been approved by UL for Class I Division 2 Group D (methane group of gases) without the need for any barrier – UL file E467390. See the Control Drawing 50021.
