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Meeting Minutes

Technical Committee on Fundamentals of Fire Alarm and Signaling Systems

Report on Comments (ROC) Meeting October 10-12, 2011

Richmond, VA

(Pending Approval by the Committee at the 2013 Pre-ROP Meeting)

1. Meeting Location and Date: Marriott Hotel, Richmond, VA - October 10, 2011

October 10, 2011 1.1 Meeting called to order by Chair Clary at 8:00 A.M on 10/10/11.

Moment of silence observed in honor of former committee member Larry Esch who passed away this summer.

1.2 Chair Clary introduced himself to the committee. 1.3 NFPA Staff, Michael Fontaine, introduced himself. Reviewed restroom locations and building

safety information. 1.4 Self-introduction of SIG-FUN members and NFPA staff were made. 1.5 Shane Clary provided an overview of the agenda. 1.6 NFPA Staff provided a presentation on the general rules and procedures governing the

committee activities; as well as, the NFPA 72 revision schedule. 1.7 Comments/Questions from Committee Members and Guests. There were none. 1.8 Chair Clary asked for approval of the minutes from the SIG-FUN ROP meeting in San Diego.

Motion made and approved to accept minutes as written. 1.9 Dismissed task groups to work on comments until noon. Group to reconvene at 1:00 p.m.

unless prepared to proceed earlier. Task group 5 - new chair is Sandy. Fred is not in attendance. Shared info that NFPA Research foundation is not working protection of control panel,

but is working methodology for addressing unwanted alarms. 1.10 Groups reconvened at 11:00 a.m. 1.11 TCC Chair Schifiliti spoke on 72-238 clarifying SIG-FUN action it to approve deletion of 10.19

only and that SIG-TMS is addressing the balance. SIG-FUN is providing recommended definition revisions to SIG-TMS.

1.12 Bruce Fraser spoke on activities performed by the TCC Documentation Task Group. Comment developed to recommend minimum documentation requirements for all systems, except household.

October 11, 2011 1.13 Chair Clary called the meeting to order at 7:30 A.M. 1.14 TCC Chair Schifiliti spoke on action taken for 10.10.8 and asked that the committee work more

diligently to reach consensus on issues like this one and protection of control panels. 1.15 Chair Clary dismissed the meeting at 6:15 P.M. October 12, 2011 1.16 Chair Clary called the meeting to order at 7:30 A.M. 1.17 TCC Chair Schifiliti spoke on the term enforcement authority that is being used by the TCC in

lieu of AHJ

1.18 IAFC Representative Jack Sparrow spoke in the interest of efforts being pursued by the IAFC to

reduce unwanted alarms. 1.19 Dan Decker provided a presentation from the task group on circuits and pathways. As a part of

the presentation galvanic isolated ethernet connection and ground fault failure mechanisms were discussed. It was noted that a company has filed a patent application for a method to provide ground fault detection in these types of pathways. [Enclosure]

1.20 Dan Gauvin provided a presentation on pathways and circuits that was developed by AJ Capowski of the Circuits and Committee Task Group. The presentation covered history of ground fault detection in UL 864 from the 7th and 8th edition. 7th edition was only concerned with ground faults that could cause failures in the system. Compared ethernet pathways to signaling line circuits which need ground fault detection. Tests performed to determine impact of ground faults on ethernet pathways using a 7 foot cable. When pin 8 had a earth fault the signal crosstalk became more severe and failed the TSB155 test. 2nd test was performed to determine actual impact on communications between PCs. Unimpaired cables with ~6MB had 83 DLL errors; however with earth faults error rate when up significantly. If ground fault detection is required, a standard manufacturer switch may not meet this requirement. Switches that support ground fault detection are available from at least one manufacturer. [Enclosure]

1.21 Meeting dismissed at 7:30 P.M.

2. Committee Members in Attendance:

2.1 NFPA staff have been unable to locate the sign-in sheets from the meeting. 3. Guests Attending

3.1 October 10 Robert Schifiliti Jack Parrow Bruce Fraser Lee Richardson

3.2 October 11

Robert Schifiliti Jack Parrow

3.3 October 12

Robert Schifiliti Jack Parrow

4. Committee Generated Proposals/Comments:

4.1 CC-200 4.2 CC-201

5. Number of committee generated proposals/comments:

5.1 The committee generated two comments. 6. The following task groups remained together as assigned at the ROP Meeting:

Task Group 1 Scope: Proposals related to Chapter 3, Definitions Chair: Jack McNamara Members: Chester Maciaszek, Jeff Hancock, Maria Marks, and David Stone

Task Group 2 Scope: Proposals related to Documentation Chair: Scott Jacobs Members: Kim Gruner, and Dan Decker Task Group 3 Scope: Proposal related to items 10.3 - 10.9, and 12.2 Chair: Andrew Berezowski Members: William Wayman, Dan Goodyear, and James Ditaranto Task Group 4 Scope: Proposals related to Items 10.10-10.14 Chair: Manuelita David Members: Daniel Gauvin, Walter Kessler, Richard Maladay, and Eric Apolenis Task Group 5 Scope: Proposals related to items 10.15 - 10.16 Chair: Fred Leber (Sandy acted in Fred's absence at the ROC) Members: Robert Bonifas, Sandy Egesdal, and David Frable Task Group 6 (Note: Scope and members combined with Task Group 2) Scope: Proposals related to items 10.17 - 10.19 Chair: James Mundy Members: Thomas Norton and Todd Warner

The following new Task Group was formed at ROC meeting: Task group on the future vision for fire alarm systems Scope: Review standard to determine whether or not conventional panels have a place in the future editions of NFPA 72 based on the benefits provided by current technology for addressable control units. Chair: Jim Mundy Members: Dan Gauvin, Jack McNamara, Jon Kapis, and Andrew Berzekowski.

7. Committee Statements Requiring Technical Correlating Committee attention:

7.1 Not applicable. 8. Committee actions that need to be referred to another technical committee for correlation:

8.1 Not applicable. 9. List any additional information that you feel would be helpful to the Technical Correlating

Committee, staff, or to the process in general:

9.1 Not applicable. 10. Issues that should be brought to the attention of the NFPA Research Foundation for their input and assistance:

10.1 Not Applicable.

Jeff Hancock

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For NFPA Technical Committees

Ground Fault Detection and Reporting

Th i i l The original reasons

Today’s arguments

Transmission tests

The reasons we believe the Code needs changes

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Per NFPA Staff research, requirement for ground fault detection was present in editions of NFPA 72fault detection was present in editions of NFPA 72 dating back to 1964, and may have originated prior to 1964

At that time, fire alarm systems were either AC powered circuits typically 120VAC or DC poweredpowered circuits, typically 120VAC, or DC powered circuits, typically 24VDC.  In either case, ground faults had the capability of creating a false alarm

NFPA 72

Annex G:

• Galvanically isolated circuits prevent the propagation of shorts or grounds, and only interrupt communications if the short is across a matched pair.

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• Ethernet ‐ Communications  is impacted only when pins (1 d 2) (3 d 6) h t d O l 2 t f 28 (7%)(1 and 2) or (3 and 6) are shorted.  Only 2 out of 28 (7%) possible short circuit conditions on the cable will impair communications.

“Allowing an undetected ground fault could affect my panel in adverse, unknown ways”

“Galvanically isolated” wiring is our recommended new exemption to ground fault detection. 

The isolation prevents the propagation of adverse wiring conditions to other circuitsconditions to other circuits.

Shorts, opens, grounds, and even electrical interference are known conditions handled by protocols that verify the integrity of data.

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Considering the original reasons for ground fault detection, and considering today’s technology, we hope you will agree that we should allow the new solutions that are available.

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For NFPA Technical Committees

Ground Fault Detection and Reporting

Hi t History

Why we do it

Some test results

Ramifications of eliminating it

Ramifications of keeping it.

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NFPA 72 did not require ground fault detection on local systems until 1993.y

UL864 7th edition (applied until 1996) only required detection of “a single ground fault condition that prevents the required operation of the system.”

It was not until 1996 and the 8th edition that full ground fault detection was required.fault detection was required.

It is convenient to argue that ground fault detection was required because of 120 volt systems, but it is not accurate.

120V bell circuits and 120V IDCs were extinct by this time.

A ground fault only occurs on a failed wire. The failure may not immediately affect operation but it is The failure may not immediately affect operation, but it is a failure none the less.

In some cases the first ground fault will affect operation (see slides on test results).  In some cases it requires subsequent ground faults to affect operation.

Wi i f lt th l t f i ll Wiring faults are the largest cause of service calls for the SimplexGrinnell service department Ground faults are the largest cause of wiring faults.

The only other cause that comes close is dirty detectors.

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Two grounds effectively short two parts of the system togethersystem together.

For non‐isolated circuits this can cause the entire panel to fail.

For isolated circuits it can cause one or more of the circuits to fail.

The goal of supervision is to keep a system running g p p y gwhile warning of issues.

We live with failures that affect operation (e.g. shorts), but that is not desirable.

Because they are pervasive in real building installationsinstallations.

Because they cause the system to operate incorrectly.

Because it is easy and inexpensive to do.

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What is…

S i l di it l i ti i ? Serial digital communications over copper wire?

Isolated communications?

Ability to provide power over the communications wires?

Error detecting protocol with retries?

What is…

S i l di it l i ti i ? Serial digital communications over copper wire?

Isolated communications?

Ability to provide power over the communications wires?

Error detecting protocol with retries?

a ) Etherneta.)  Ethernet

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What is…

S i l di it l i ti i ? Serial digital communications over copper wire?

Isolated communications?

Ability to provide power over the communications wires?

Error detecting protocol with retries?

a ) Etherneta.)  Ethernet

b.)  SimplexGrinnell’s IDNet

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• Some members of the wiring task group maintained that because Ethernet was isolated it could not be affected by earth faultsaffected by earth faults.

• This was disputed by other members.

• In an effort to settle the issue, Tyco Fire Protection Products conducted a series of tests to determine if

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Products conducted a series of tests to determine if isolated Ethernet is affected by earth faults.

• For this test, a Fluke DTX‐1800 with Alien Cross‐Talk Option was used. 

lk h l f h• Cross‐Talk occurs when two signals interfere with each other, causing communications errors.

• Alien Cross‐Talk is caused by a signal within a different cable.

• The tests were performed to the requirements of

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• The tests were performed to the requirements of TSB155.  

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Short cables, 7 ft in length, were tested, without earth faults.  The cables passed the TSB155 tests with great marginmargin.  

38.6 dB worstcase margin.

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The next step was to measure the same cables with earth faults to one conductor of each cable (pin 8).

The result is a failure, per TSB155.  Note that this failure occurred with 7 feet of cable.  The signal to noise ratio will get worse with distance 

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Margin decrease of  72.9 dB!!!

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The next test was to measure the effects on actual communications with earth faults.

Two pair of PCs were set to send data between them.  One link was monitored by an Ethernet analyzer.

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PC1 to PC2 is 100 meters in length.

PC3 to PC4 is about 4 meters.

The chart shows the result of the tests.  The unimpaired cables sent 6,011 Megabytes with 83 DLL errors.  When earth faults were introduced to one conductor of eachearth faults were introduced to one conductor of each cable, the Ethernet Analyzer recorded 204,842 DLL errors over (slightly) fewer frames. 

The error rate went from 0 to 165.5 errors per second.

Results are for approx. 7.5 million frames

Unimpaired Cables

Two ethernet w/earth fault

% utilization 20% 20%

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to 165.5 errors per second.

The earth faults affected the communication link.

% utilization 20% 20%

Frames 7,667,792 7,412,729

Bytes 6,011,000,000 5,807,000,000

DLL Errors 83 204,842

Frames / Sec 6326 6201

Bytes / Sec 5,070,000 4,988,000

Errors / Sec 0 165.5

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No isolated circuit will require ground fault detection.  This includes: The detector loops from many manufacturers.

The network loops from many manufacturers.

Installers hate ground fault detection.  Panel manufacturers will quickly move to all isolated circuits to eliminate it.

The overall reliability of systems will decline. The overall reliability of systems will decline.

NFPA72 may be supplemented by state regulations in certain jurisdictions (e.g. Florida) and lose some of it’s authority as the sole source for fire alarm requirements.

You won’t be able to drop a Cisco switch into your systemsystem.

Some manufacturers will have to add ground fault detection to their products in order to participate in the fire detection/ECS market.

Your system will continue to be reliable.

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Isolated SLC’s are not new.

Ethernet is not magic.   Like all SLC’s it is affected by ground faults.

NFPA 72 ground fault requirements have evolved and grown over time driven by real field issues and experience.

We are being asked to remove ground fault detection so that commercial grade equipment (most of which is 

h b d b h l f h d ) b dprohibited by other elements of the code) can be used to build life safety systems.

The committee should reject these proposals.