Surge Protection for Heat Trace Control Panels (UL508A)

Heat Trace System

OVERVIEW

Today's increased reliance on very sensitive electronics makes surge protection an important topic for Heat Trace Control Panels listed to UL508A. The Insurance Institute for Business & Home Safety study found that $26 billion dollars was lost due to non-lightning power surges. In addition, there are about 25 million lightning strikes in the US each year that cause between $650M to $1B in losses according to the Insurance Information Institute, State Farm©.

Selecting SPD for UL508A Heat Trace Control Panels

NEC/NFPA 70 require that Surge Protective Devices (SPDs) shall be UL1449 Listed. This means selecting a surge protector is easier than it has ever been. There are only a few choices available for SPDs that are UL Listed for any of the most commonly used surge standards including UL1449 5th Edition, UL497B, and UL497E.

Heat Trace Control Panel

Recommended SPD for Heat Trace Control Panel

Location	Equipment	System	Surge Protector Model#	Link
	Distribution Panel	120/208V 4W+G, Wye	MS200-120Y
	AC Power Input	120V 1ph 2W+G	DS72US-120S/G
	Sensor Input	Leased Line 4-20mA	DLA2-24D3
	Heat Cable Output	120V 1ph 2W+G	DS72US-120S/G
	Internal Gateway	1Gbps Ethernet	MJ8-C6A
	Communication Output	RS232, RS485	DLA2-24D3

Determining the acceptability of an SPD
for UL 508A Industrial Control Panels and All Other UL Listed Equipment

The UL inspector will first consider the SPD type when determining it’s acceptability for a given application or piece of equipment. This will include UL 508A as well as all other UL Listed equipment. The first level compliance is based on the UL Approval (LISTED or RECOGNIZED) of the SPD or UL SPD Type and it’s Suitable Ratings. This means that it has to meet all safety, performance, environmental and electrical system ratings of the application. If any of these criteria are not fully met, it will require a Procedure Description, a File Update and/or Additional Testing. These actions will require additional costs that may be substantial. For this reason, it is in the interest of the specifier to use UL LISTED SPD’s to eliminate any uncertainty or to make sure the UL RECOGNIZED SPD is selected at the time of UL submittal of the equipment.

Approval Considerations Table based on UL SPD Type

UL Mark	UL1449 SPD Type	Suitable Ratings	Procedure Described	File Update or Additional Testing	Notes
	1 2	Yes	No	No	The only requirement is that the SPD must match electrical and environmental ratings of the UL 508A Control Panel. A UL field inspection of the control panel with the SPD installed is required as a part of a standard follow-up service visit.
	1CA 2CA 4CA 5	Yes	Yes	Yes	Yes – All UL recognized SPD’s require a UL engineering evaluation of the SPD’s existing UL1449 E–file. This will result, at a minimum, in a cost to update the UL file and may also require testing that would result in additional costs.