Understanding Safety Harness Use: When and Why to Employ Fall Arrest Systems at Heights

A personal fall arrest system - safety harness with a shock-absorbing double lanyard is being recommended for working at heights. Kindly help with the following queries:

1. At what height should the PFAS be employed and why?
2. At what height can this type of safety harness with a shock-absorbing lanyard be used?

Recently, the use of this equipment has been enforced. Let's gain a clear understanding of fall protection, please.

Regards,
Kesava Pillai

Dear Keshav Pillai,

Good Topic...

My answers are as follows:

Definition of Fall Protection

Fall Protection is defined as the means of preventing workers from experiencing disastrous accidental falls from elevation by effectively using Fall Arrest Equipment, also known as Personal Protective Equipment (P.P.E.).

1) At what height should PFAS be employed and why?

PFAS are required when the risk of falling from an elevated level exists. It is advisable to use them from a height of 2 meters and above.

2) At what height can this type of safety harness with shock-absorbing lanyard be used?

Shock-absorbing lanyards work by the unfolding and tearing of stretched webbing to reduce the impact load experienced by the worker. The length of stretched webbing is 1.8m, the lanyard length is 1.8m, and the worker's length is approximately 1.8m. Rounding up the three, we can consider it as 6m. This type of Safety Harness is only advisable to use if you are getting a clear, free-falling span of at least 6 meters or above. Otherwise, in case of a fall, the person will come to the ground, rendering the entire purpose ineffective.

Regards,

Dipil Kumar V

Dear Sir,

All jobs above 2m, where a permanent platform with railing is not present, or an extended platform is present, require the use of a full-body, double lanyard safety belt. A fall arrestor can be used with a full-body double lanyard while moving vertically up or down.

Regards,
Hansa Vyas

Dear Friends,

When a safety man is on-site, people look to him for advice. In terms of safety, his words are final. Are we prepared?

Let us understand things from the right perspective as professionals.

Read My First Question

At what height should PFAS be employed and why? This question pertains to PFAS and not fall protection as such. PFAS is distinct from fall protection.

Fall protection aims to prevent a fall by creating a barrier between the person and the fall hazard, thereby preventing individuals from reaching the fall hazard.

A Personal Fall Arrest System (PFAS) halts a fall that is already in progress through a tie-off system.

At what height should PFAS be used? Answer: Above 6 feet.

Why? Answer: Research shows that falls from heights above this are often fatal.

Now, can we use a safety harness with a shock-absorbing lanyard above 6 feet? The answer is NO. It is not designed for use at such heights.

So, at what height can we use it? The answer is when the free fall distance is more than 19.5 feet.

Hansa, please bear with me. Allowing workers to use safety harnesses with shock-absorbing lanyards at heights less than 19.5 ft gives them a false sense of protection, rendering it ineffective.

What Dipil mentioned about the free fall distance of 19.5 feet or 6 meters is correct. However, please note that the shock absorber's elongation is limited to only 3.5 feet, not 6 feet (1.8 meters). Your calculations need some correction.

So, how will you calculate the distance?

Kindly check the attached PowerPoint presentation. It may provide a clearer understanding.

My writing style may be a bit different. Nevertheless, if my posts benefit those who read them, I will be happy to share more of the knowledge I've gained over the years.

Regards,

Kesava Pillai

Dear Sir, Really great reply... Saluting your sharing mentality... A small doubt from the presentation... Hope you will not mind it and expecting a reply...

As per the presentation, the free fall distance coming is 11 feet...

Now please go through the below two sentences:

"Free Fall Distance is measured from the D-ring of a worker standing on the work surface down to the point where either the lanyard or the shock absorber begins to arrest the fall. It is strongly recommended that this distance be kept as short as possible."

"To minimize free fall, workers should tie off to an anchor point overhead and use as short a lanyard as the work will allow..."

Now my questions are:

1. Even though the worker anchors his lanyard to an elevated position, as we are calculating the free fall distance from the D-Ring, will the free fall distance remain the same or not?

2. As per the presentation, the calculation is made when the anchorage is at your feet... Can we advise an anchorage at feet? If not, what will be the perfect height of the anchorage point we can advise and why?

Waiting for your reply.

With regards,

Dipil Kumar V

Dear All,

Please find the attached file herewith for a clear understanding of working at heights. Kindly go through the document and provide your comments.

Shailesh Mistry
Safety Professional
09898402719

Hi, sir,

Thank you for the discussion and PPTs; really, it gave an in-depth understanding. Such offline discussions are really beneficial.

Major N Sekar

Dear All,

How can we calculate the impact load generated on an anchorage point in case of a fall? What should be the minimum advisable shock load for an anchorage point when attaching a lanyard?

With regards,
Dipil Kumar V

Dear Dipil, I came across the following site while browsing, but I have not gone through it fully. I feel that this can answer your question to some extent.

http://www.fallsafety.com/faq_topic....orage%20Points

Regards

We can calculate the impact load generated on an anchorage point with the help of a load cell attached to a dummy of 100 kg, simulating a fall with a harness connected to an energy-absorbing lanyard. The impact load will be less than 4.5 kN (EN 355). The minimum advisable shock load of an anchorage point for attaching a lanyard should be 10 kN (EN 795).

Hope this clarifies the issue.

Regards,
Ravi

Could you please provide me with the exact calculation of how this 4.5 kN impact load is generated when a person falls?

Regards,
[Name]