After attending an ASA Safety Committee meeting, I learned of the Dennington harness.  Does anyone have any input on how well they work?  Pros of the system, cons of the system?  I'd like to know from first-hand experience rather than advertisement.  Anyone can make themselves sound good.

Considering a majority of places our company works have fairly low elevations between floors, I'm thinking this may be a good idea.

-Justin

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Eat. Skate. Sleep. Repeat.

Looks a little gimmicky to me and I'm not sure I buy the claims on the web site.  I've never heard of them before.  Maybe try one out?

I got to see one in person, handle it, and see it tried on.  Two differences I noticed right away were the stretchy ropes on the back and there's a strap that runs just under your butt to act like a seat when in suspension, supposedly relieving some strain to the legs.

The trick is convincing the person in charge of ordering harnesses (not me, unfortunately) to spend the $175 to get a mid-range model.

Right on the homepage of Dennington is...

"The Dennington Safety harness has received the highest certification in fall protection history to the original federal specification which allowed only a maximum fall distance of 6 ft.  That specification did not allow an extra 3½ ft. of elongation."

OSHA currently allows a FREE FALL of six feet... and the fall cannot result in a contact with a lower level.  They use the words original federal specification.  Since I came into safety not too long ago, I'm not familiar with previous OSHA standards regarding fall protection.  Seems like they're doing a little play on words to help business.

-Justin

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Eat. Skate. Sleep. Repeat.

That's one of the things that caught my eye, as well.  The rule says six feet maximum free fall.  That is to say, the arresting action of the fall protection system must activate within six feet.  Shock absorbers are and have been legal for a long time (max deployment is 3.5 feet).

Right... they're legal as long as the employee doesn't contact the lower surface.  With that said, Dennington is correct in the sense that several personal fall arrest systems are out of compliance due to the extension of several shock absorbers, assuming they extend completely.  However, it's highly unlikely a shock absorber will fully deploy if there's a low-height fall.  If clearance isn't enough, not even a Dennington will work.  Their lanyards are 5'0" (if I remember correctly).  Add five feet from the D-ring to the worker's feet... 10'0".  Add 8" for the bungees stretching... 10'8".  Add another 6" or so for the D-ring raising up... 11'2".  Well look at that... a 10' slab-to-slab won't work. 

Am I right on that one?

-Justin

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Eat. Skate. Sleep. Repeat.

Shock absorbers can extend 3.5 feet.  That's legal.  So you can have a 6 foot free-fall, plus 3.5 feet deceleration for a total of 9.5 feet.  There will also be some stretching, as you indicate, and that is legal too - as long as you don't hit the lower level.

You only add 5 feet from floor to D-ring if the anchorage point is at or near the worker's feet.  If the anchorage is overhead (as is preferred), then the distance will be the height of the anchorage point above the worker's feet, minus the total distance from the floor to the D-ring (approx 5 feet) plus the length of the lanyard.  In other words:

Free Fall Distance = AH - (D + LL)

AH = Anchorage Height (vertical distance from the worker's feet to the anchorage point)
D = Vertical distance from the worker's feet to the D-ring
LL = Lanyard length

This assumes a reasonably straight vertical line between all the points (anchorage, D-ring and worker's feet).

Hope that makes sense.

Say the anchorage point is 10'0" above the finished floor.  The worker has a 5'0" lanyard.  Let's say he's about 6'0" tall, making the D-ring in the center of his back about 5'0" off the ground.  Assuming you're using that "super safe" Dennington harness, add 8" for stretching of the bungees and about 8" for the harness being pulled off the body due to suspension.

5'0" + 5'0" + 8" + 8" = 11'4"

That's 16" more than the anchorage point height.  Even if the employee is tied off above his head to that 10'0" anchorage point, he/she will still hit the ground, UNLESS a retractable lanyard is being used.  Then one would have to assume the retractable would engage it's locking mechanism properly.

-Justin

P.S.:  Fall protection has got to be one of the more frustrating aspects of safety.

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Eat. Skate. Sleep. Repeat.

If the anchorage is 10 feet above the finished floor, the lanyard will be nearly taut when hooked to a D-ring 5 feet above the floor.

Free Fall Distance = AH - (D + LL)

Free Fall Distance = 10 - (5 + 5)

Free Fall Distance = 0

Too many different scenarios to choose from.  The few inches from D-ring travel will let the employees feet hit the ground IF HE FELL.  He won't be working on the ground and be tied off... that's what I'm getting from your formula.

Anchorage point  = 10'0" above floor
Feet on the ground to D-ring = 5'0"
Lanyard length = 5'0"

In order for zero free fall, he would have to be standing on the ground.

-Justin

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Eat. Skate. Sleep. Repeat.

I'm suggesting that the fall is measured from the object or platform which supports the worker.  So, I'm working under the assumption that the anchorage point is 10 feet above that point.  However, I don't think that is what you mean now that I think about it.  The important measurement is the anchorage point height above the object or platform that supports the worker (when calculating the free-fall distance, that is).

Right.  I was saying the point is 10'0" above the floor... or 4'0" above the working surface (going on the assumption the surface is 6'0" above the ground).

-Justin

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Eat. Skate. Sleep. Repeat.