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Re: Fall Protection - Safety Factors

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There are a couple things that may lead to confusion:
1) maximum force on 310 lb (mass) falling employee (interesting limitation)
is 1800 lbf and the deceleration must start within 6' (OSHA as noted below)
of free fall (5' in Canada). If you do the energy numbers, this can be
difficult to manage. Shorter free fall is always better but it may be
restrictive to the work.
2) the ANCHOR, regardless of the personal fall arrest system, must be
capable of resisting 5000 lbf ultimate with FS=2. Usually an anchor is
considered to be located immediately overhead of the work position. Any
variation from that may lead to other complications in the design of the
system and procedures.

Self-retracting lanyard is not necessarily a shock-absorbing lanyard. The
fall protection industry has progressed significantly in the last 15 years.
It's amazing what you can buy ... and buy again after a minor incident.

It's all about energy, now - the artificial static force methods are
obsolete. Anchors are considered to be relatively rigid and all of the
energy has to be resolved between the anchor and the falling person. That's
one of the reasons for special requirements with a 310 lbs (mass) person for
the default limit condition AND the apparently high 5000 lbf per person
anchor limit.

Unless you have done this work recently or are prepared to spend a lot of
time to investigate and specify elements of the personal fall arrest system,
stick to the anchor and let a specialist design the system.

I just see the $$$$ every time a contractor calls and complains about being
shut down over equipment/procedures that they've been using for years ....

Regards
Paul
-- 
Paul Ransom, P.Eng.
ph 905 639-9628
fax 905 639-3866
ad026(--nospam--at)hwcn.org


> From: Jim Getaz <jgetaz(--nospam--at)shockeyprecast.com>

> Dave,
> 29 CFR 1926.502(d)(15) "...at least 5,000 pounds ... with a=
> factor of safety of at least two..."

> It takes a pretty substantial lug.
> Jim Getaz


> From: "Gary L. Hodgson and Assoc." <design(--nospam--at)hodgsoneng.ca>

> That looks like a pretty confusing document to me. Have they not heard
> of headings and sub-headings, tables and other means of making a
> document easy to use and understand.
> Gary


> From: Paul Blomberg <paul.blomberg(--nospam--at)gmail.com>

> safety of two.  I haven't check the OSHA regs in a long time but below is
> what I saved to justify the approach.  You can take the arresting force as
> 1800 lbs. as that is the limit that OSHA will allow on the body when you use
> a harness.  If you use a self retracting lanyard, I believe the force is
> limited to 900 lbs.
> 
> If you are a PE then OSHA will take you as a Qualified person as long as you
> are working in your competencies.
> 
> Paul.
> Phoenix
> 
> 
> OSHA Regulations (Standards - 29 CFR)


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