2017 NEC and CTs

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SparkyTim

Member
Location
Austin, TX, USA
Hi,
New poster here, I hope this is appropriate.
I was hoping someone would know about some of the new language in the 2017 NEC. A customer is installing a CT based submeter in an existing panel. As TX has just recently adopted the 2017 NEC, I think the inspector might be interpreting the new language too harshly.
The main question revolves around the new 312.8 (B1) wording;
(1) The power monitoring equipment is identified as a field-installable accessory as part of the
listed equipment, or is a listed kit evaluated for field installation in switch or overcurrent device
enclosures.
The meter is "listed" to 61010 as are the CTs. Which seems like it meets code. The inspector's issue is with the CTs. He's saying the new code means that the CTs have to be XOBA - UL2808 listed.
I'm not seeing XOBA or UL2808 anywhere in the 2017 NEC... I don't see anywhere there's any mention of CTs at all.

What's the proper code/specification for CTs in residential settings?
What's difference between the 2014 NEC and the 2017 NEC for sub-meter installations?

This is a picture I found that looks similar to what we're doing. (Green things are the CTs).
Typical installation.PNG
 

raider1

Senior Member
Staff member
Location
Logan, Utah
Welcome to the forum.

UL Product Category FTRZ covers Energy Usage Monitoring Systems and is referenced in UL's Product Spec to comply with 2017 NEC 312.8(B)

This category covers products intended for use in metering of utility and nonutility electric power. The primary function of these devices is to monitor power consumption on a building main supply or separate branch circuits. These devices may communicate with other devices by means of power line carrier, satellite/radio frequency, telephone, cable or other means. Devices suitable for outdoor use are so marked.

One of the following product identities should appears on the product:

Energy-usage Monitor

Sub-metering Equipment

Watt-hour Meter

The basic standards used to investigate products in this category are UL 916, "Energy Management Equipment," or UL 61010-1, "Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use - Part 1: General Requirements," and UL 61010-2-030, "Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use - Part 2-030: Particular Requirements for Testing and Measuring Circuits."

So if the meters and CT's are listed as a system under UL 61010-1 and 61010-2-030 then they would fall under this Product Category.

If you have more information on the particular meter and CT system that you are installing I may be able to find out more information for you.

312.8(B) was added to the 2017 NEC to clarify that power monitoring equipment mounted in panels need to be listed and not just a recognized component. The 2014 never really addressed this.

Components covered by UL’s Recognized Component program are intended to be installed in another device, system or end product. They are to be installed at the factory, not in the field and they may have restricted performance capabilities that limit their use.

Chris
 

SparkyTim

Member
Location
Austin, TX, USA
Thanks

Thanks

Don, Chris,
thanks for the replies!
The link to UL by code section was new to me... thanks for that.

Chris,
I don't want to confuse things by naming a particular product, in case anyone ends up thinking it's good or bad.
my quick take-away from your comments;
The CTs need to be XOBA and the meter needs to be FTRZ listed. OR or the system including the CTs needs to be FTRZ.

Thanks again for the help.
 
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