Machine Safety: My main disconnect e-stop isn’t red with a yellow background

Does my main disconnect functioning as an e-stop need to be red with a yellow background?

07/05/2012


Jokab Safety giant E-Stop at Pack Expo 2010Does my main disconnect functioning as an e-stop need to be red with a yellow background?

 

This has long been an active area of discussion in manufacturing. In fact, using a main disconnect as an emergency device for removal of power has a long history. Some of us might remember when machines evolved to having their own machine mounted motor and or drive. Soon after this evolution the crow bar circuit emerged for emergency stopping a machine. I expect young folks today would laugh at seeing someone pick up a crow bar and throw it at the three main leads shorting out the current. An e-stop was born!

 

Banner Engineering's 30mm Mount Illuminated Emergency Stop Pushbutton is IP65-rated and is designed for emergency stop safety applications. Courtesy: Banner EngineeringFast forward to today and realize that the discussion about main disconnects being used as an e-stop device was only recently updated in NFPA 79 – 2007, Clause 10.7.4 Local Operation of the Supply Disconnecting Means to Effect Emergency Stop. The last updated NFPA 79 – 2012 made no changes to these requirements. The requirements of this Clause are: 

10.7.4.1 The supply disconnecting means shall be permitted to be locally operated to serve the function of emergency stop as follows:

Safety integration webcast, Control Engineering at www.controleng.com/webcast(1) Where it is readily accessible to the operator

(2) Where it is of the type described in 5.3.2(1), 5.3.2(2), or 5.3.2(3)

10.7.4.2 Where used as an emergency stop, the supply disconnecting means shall meet the color requirements of 10.7.3.

10.7.4.3 Disconnecting (isolating) electrical devices as described in 5.5.4, where accessible to the operator, shall also be permitted to serve the function of emergency stop. _____________________________________________________________ 

The additional requirements that I understand are that every machine needs to have at least one e-stopping device as determined by the risk assessment, that it needs to be red with a yellow background per 10.7.3 and that it needs to be accessible by the operator. ANSI B11.19 – Performance Criteria for Safeguarding normatively references NFPA 79 – 2007 as required.

Is anyone still confused?

 

Your comments or suggestion are always welcome so please let us know your thoughts. Submit your ideas, experiences, and challenges on this subject in the comments section below. Click here controleng.com/blogs if you don't see a comments box, find, and click into: Machine Safety: My main disconnect e-stop isn’t red with a yellow background, and scroll down.

 

Related reading and articles:

ANSI B11.19-2010, Performance Criteria for Safeguarding

NFPA 79 – 2012, Electrical Standard for Industrial Machinery

E-Stops and Your Compliance

E-Stops Aren’t Safety Devices

 

Contact: www.jbtitus.com for “Solutions for Machine Safety”.



No comments
Consulting-Specifying Engineer's Product of the Year (POY) contest is the premier award for new products in the HVAC, fire, electrical, and...
Consulting-Specifying Engineer magazine is dedicated to encouraging and recognizing the most talented young individuals...
The MEP Giants program lists the top mechanical, electrical, plumbing, and fire protection engineering firms in the United States.
Integrating electrical and HVAC systems; Tracking and conserving facility water use; Energy code advancements; The future of professional engineers
Control noise, vibration in building design: Tackling acoustics and design issues; High-performance building design; NFPA 99; Combined heat, power
40 Under 40; Stand-alone medical buildings; NFPA 92; Specialty fire suppression; Applying 90.1 in lighting design
Putting COPS into context; Designing medium-voltage electrical systems; Planning and designing resilient, efficient data centers; The nine steps of designing generator fuel systems
Designing generator systems; Using online commissioning tools; Selective coordination best practices
Understanding transfer switch operation; Coordinating protective devices; Analyzing NEC 2014 changes; Cooling data centers
As brand protection manager for Eaton’s Electrical Sector, Tom Grace oversees counterfeit awareness...
Amara Rozgus is chief editor and content manager of Consulting-Specifier Engineer magazine.
IEEE power industry experts bring their combined experience in the electrical power industry...
Michael Heinsdorf, P.E., LEED AP, CDT is an Engineering Specification Writer at ARCOM MasterSpec.
click me