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CSA Z432 Third Edition Open for Public Review!

2015 November 3
by Doug Nix

CSA Z432, Safeguarding of Machinery, is the basic standard for Canada when it comes to most types of machinery. Only Power Presses and Press Brakes, and Industrial Robots are covered separately in their own standards. CSA Z432 provides guidance on important topics, like:

  • Risk Assessment
  • Risk reduction through the Hierarchy of Controls
  • Guard design requirements
  • Safeguarding device application requirements, and
  • Instructions and information for use

This standard should be used by everyone in Canada responsible for the safe design of machinery used in Canadian workplaces, and for the safety of workers who use machinery in their daily tasks.

CSA has just opened public review on CSA Z432, Safeguarding of Machinery, third edition. If you are a user, a builder of machinery, or an evaluator of machinery, this is your opportunity to see the draft of this important standard, and to make comments to help the Technical Committee improve the standard on your behalf.

To access the public review copy, you must register on CSA’s Public Review system. Registration is free and allows you to get read-only access to the drafts of all new standards that CSA is preparing to publish. The time you take to read and comment on new standards is very valuable to the Technical Committees, as it helps us to correct areas where misunderstandings or confusion may exist, and to add material where it is needed.

See the Draft

Review closes 2-Jan-2016, so don’t delay!

If you need more information, please contact Jill Collins at CSA Group.


Public Review: CSA Z1006 Management of Work in Confined Spaces.

2015 July 30
Comments Off on Public Review: CSA Z1006 Management of Work in Confined Spaces.
by Doug Nix

CSA Z1006 Management of Work in Confined Spaces  is now available for Public Review. 

As new standards are developed, and existing standards are revised, they are made available for public review and comment. If you are interested in Confined Space Entry, and would like an opportunity to review the proposed changes to the standard, read on!

Management of work in confined spaces, New Edition | CSA Public Review System

This Standard specifies requirements for and provides guidance on the activities required to manage all aspects of work in confined spaces in accordance with the Plan-Do-Check-Act cycle and management system principles such as those set out in CSA Z1000-15, Occupational health and safety management. This Standard specifies requirements concerning management commitment, leadership, and participation, assignment of roles and responsibilities, identification of confined spaces, identification of hazards, risk assessment, selection and application of controls, design considerations, training, monitoring and measurement, emergency response, documentation, internal audits, and management reviews.

Five informative Annexes provide guidance on implementing this Standard’s normative requirements, including sample forms that can be customized for the specific needs of the user.

This Standard provides:

(a)   An overview of the steps an organization needs to take to establish and maintain an effective confined space management program;

(b)   Safety information for workers entering confined spaces and for persons responsible for ensuring the safety of such workers; and

(c)   Requirements for confined space emergency preparedness and rescue.

Clause 4 specifies general requirements for a comprehensive confined space management program.

Clauses 5 to 8 specify requirements for planning and implementing a confined space management program. Clause 5 specifies roles and responsibilities. Clause 6 specifies requirements for hazard identification and risk assessment, development of entry procedures, emergency response planning, and assessment of worker capability for performing assigned duties within a confined space. Clause 7 specifies requirements related to training, Clause 8 specifies requirements related to controls, emergency response activities, and documentation.

Clauses 9 and 10 specify requirements related to incident investigation and analysis, corrective actions, internal audits, and management reviews. These activities can help ensure worker safety and facilitate continual improvement of a confined space management program.

Changes in this edition include:

a)    Improved flow and readability of the document with the inclusion of additional flowcharts and tables and restructuring of content and clauses;

b)    Added two additional informative Annexes to elaborate and provide additional information on rescue planning and atmospheric testing, monitoring and instrumentation;

c)    Updated the document to harmonize with CSA Z1000, Z1001 and Z1002; and

d)    Elaborated on the information on workspace design and modification.

Use the following link to access the draft standard and comment on any issues you may see in the document: Management of work in confined spaces, New Edition | CSA Public Review System

Thanks to Jill Collins at CSA Group for this notification.

Scoring Severity of Injury – Hidden Probabilities

2015 July 21
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I’ve been thinking a lot about risk scoring tools and the algorithms that we use. This all started when I was challenged to write an analysis of the problems with the CSA Risk Scoring Tool that you can find in the 2014 version of CSA Z434. That tool is deeply flawed in my opinion, but that is not the topic of this post. If you want to read my analysis, you can download the white paper and the presentation notes for my analysis on the Compliance insight Publications page [1].

Scoring risk can be a tricky thing, especially in the machinery sector. We rarely have much in the way of real-world data to use in the analysis, and so we are left with the opinions of those building the machine as the basis for our evaluation. Severity is usually the first risk parameter to be estimated because it’s seen as the “easy” one – if the characteristics of the hazard are well known. One aspect of severity that is often missed is the probability of a certain severity of injury. We’re NOT talking about how likely it is for someone to be injured here; we’re talking about the most likely degree of injury that will occur when the person interacts with the hazard. Ok, let’s look at this another way. Let’s call Severity “Se”, any specific injury “I”, and the probability of any specific injury “Ps”. We can then write a short equation to describe this parameter:

Se f (I,Ps)

Since we want there to be a possibility of no injury, we should probably relate these parameters as a product:

Se = I x Ps

Ok, so what? What this equation says is: the Severity (Se) of any given injury (I), is the product of the specific type of injury and the probability of that injury. More simply yet, you could say that you should be considering the most likely type of injury that you think will occur when a person interacts with the hazard. Consider this example: A worker enters a robotic work cell to change the weld tips on the welding gun the robot uses. This task has to be done about once every two days. The entry gate is interlocked, and the robot was locked out before entry. The floor of the work cell has wireways, conduits and piping running across it from the edges of the cell to the various pieces of equipment inside the cell, creating uneven footing and lots of slip and trip hazards. The worker misses his footing and falls. What can you expect for Se in this case?

We know that falls on the same level can lead to fatalities, about 600/year in the USA [2], but that these are mostly in the construction and mining sectors rather than general manufacturing. We also know that broken bones are more likely than same level fatalities. About a million slips and falls per year result in an emergency room visit, and of these, about 5%, or 50,000, result in fractures. Ok, so what do we do with this information? Lets look at at typical severity scale, this one taken from IEC 62061 [3].

Table 1 – Severity (Se) classification [2, Table A.1]

Consequences Severity (Se)
Irreversible: death, losing an eye or arm 4
Irreversible: broken limb(s), losing a finger(s) 3
Reversible: requiring attention from a medical practitioner 2
Reversible: requiring first aid 1

Using Table 1, we might come up with the following list of possible severities of injury. This list is not exhaustive, so feel free to add more.

Table 2 – Potential Injury Severities

Possible Injury Severity (Se)
Fall on same level – Fatality 4
Fall on same level – Broken wrist 3
Fall on same level – Broken collarbone 3
Fall on same level – Torn rotator cuff 2
Fall on same level – Bruises 1
Fall on same level – Head Injury 3
Fall on same level – Head Injury 4

How do we score this using a typical scoring tool? We could add each of these as line items in the risk register, and then assess the probability of each, but that will tend to create huge risk registers with many line items at very low risks. In practice, we decide on what we think is the most likely degree of injury BEFORE we score the risk. This results in a single line item for the hazard, rather than seven as would be the case if we scored each of these potential injuries independently.

We need a probability scale to use in assessing the likelihood of injuries. At the moment, no published scoring tool that I know of has a scale for this, so let’s do the simple thing: Probability (Ps) will be scored from 0-100%, with 100% being a certainty.

Going back to the second equation, what we are really doing is assigning a probability to each of the severities that we think exist, something like this:

Table 3 – Potential Injuries and their Probabilities

Possible Injury (I) Severity (Se) Probability (Ps)
Fall on same level – Fatality 4  0.0075%
Fall on same level – Broken wrist 3  5%
Fall on same level – Broken collarbone 3  5%
Fall on same level – Torn rotator cuff 2  5%
Fall on same level – Bruises 1  90%
Fall on same level – Head Injury 3 1%
Fall on same level – Head Injury 4   0.0075%
Fall on same level – Lacerations to hands 2 90%

The percentages for fatalities and fractures we taken roughly from [1]. Ok, so we can look at a table like this and say that cuts and bruises are the most likely types of injury in this case. We can either decided to group them for the overall risk score, or we can score each individually, resulting in adding two separate line items to the risk register. I’m going to use the other parameters from [2] for this example. In the Example risk Register,

Se = Severity

Pr = Probability of the Hazardous Event

Fr = Frequency and Duration of Exposure

Av = Possibility to Avoid or Limit Harm

The algorithm I am using to evaluate the risk is R = Se x [Pr x (Fr + Av)] [1]. Note that where I have combined the two potential injuries into one line item (Item 1 in the register), I have selected the highest severity of the combined injuries. The less likely severities, and in particular the fatalities, have been ignored.

Table 4 – Example Risk Register

Intrinsic Risk Score Final Risk Score
Item # Life Cycle Stage Task / Activity Se Pr Fr Av Risk Mitigation Se Pr Fr Av Risk
1  Use: Maintenance Changing weld tip on robot welding gun: Slip and fall on same level – Bruises & Lacerations 2  5  4  3  70 Install false floor above conduits, raceways, and cables to eliminate trip hazards. 2 2 4 3 20
2  Use: Maintenance  Changing weld tip on robot welding gun: Slip and fall on same level – Bruises  1  5 4 3  35 Install false floor above conduits, raceways, and cables to eliminate trip hazards. 1 2 4 3 10
3 Use: Maintenance  Changing weld tip on robot welding gun: Slip and fall on same level – Lacerations  2  5 4 3  70 Install false floor above conduits, raceways, and cables to eliminate trip hazards. 2 2 4 3 20

Note that I did not reduce the Se scores in the Final Score, because I have not made changes to the hazards themselves, only to the likelihood of the injury occurring. In all cases we can show a significant risk reduction, but I’m not going to get into risk evaluation (i.e., Is the risk effectively controlled?) in this particular article.


Consideration of the probability of certain kinds of injuries occurring must be considered when estimating risk. This process is largely undocumented, but nevertheless occurs. When risk analysts are considering the severity of injury from any given hazard, this article gives the reader one possible approach than can be used to select the types of injuries most likely to occur before scoring the rest of the risk parameters.


[1] D. Nix, ‘Evaluation of Problems and Challenges in CSA Z434-14 Annex DVA Task-Based Risk Assessment Methodology‘, 2015.

[2] National Floor Safety Institute (NFSI), ‘Quick Facts – Slips, Trips, and Falls’, 2015. [Online]. Available: [Accessed: 21- Jul- 2015].

[3] ‘Safety of machinery – Functional safety of safety-related electrical, electronic and programmable electronic control systems. IEC 62061.’, International Electrotechnical Commission (IEC), Geneva, 2005.


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