5.2.2 1.5 m (5 ft) Setback From Leading Edge and 1.5 m (5 ft) Below the Dorsal D-Ring Anchorage
With the anchor set back and below the D-ring, as shown in Figure 6, there are seven variables to consider when calculating the MRFC.
These seven are labeled A, B, C, D, E, F, and G. H is the MRFC.
These variables are:
A = Free Fall Distance due to Below D-ring Anchorage
B = SRL-LE Deceleration Distance (Typical Overhead Distance)
C = Additional Deceleration Distance (Due to Below D-Ring Anchorage)
D = Dorsal D-Ring Shift and FBH Stretch
E = Safety Factor
F = Sub Total-Minimum Required Fall Clearance
G = Additional Fall Clearance Calculation for Swing Fall – 4’ Maximum
H = Minimum Required Fall Clearance
Use Figure 6 as a worksheet. The MRFC for this anchorage geometry is calculated as A+B+C+D+E=F. F is the Sub Total-MRFC. This total
does NOT account for swing fall. If a swing fall condition exists, use Chart 2 to determine “G”, the additional fall clearance needed. G+F=H
is the total fall clearance required.
5’ Minimum Setback from Leading Edge and 5’ Below Dorsal D-Ring Anchorage
A
2.6 m
(8.5 ft)
SRD Deceleration Distance
(Worst Case Value, See Table 1B for Exact Model)
B
0.5 m
(1.6 ft)
Dorsal D-Ring Shift and FBH Stretch
Combined amount of Dorsal D-ring up-shift and harness webbing elongation during a
fall event
C
1.5 m
(5 ft)
Dorsal D-Ring Height
Height of the Dorsal D-Ring from the walking surface
D
0.5 m
(1.6 ft)
Safety Factor -
Added length to account for other factors such as an improperly
adjusted harness, actual worker height or worker weight
E
5.1 m
(16.7 ft)
Sub Total- Minimum Required Fall Clearance
for Below D-ring Anchorage of SRD with
No Swing Fall (sum of A thru D only)
F
*Additional Fall Clearance Calculation
-
due to Swing Fall (using Chart 2)
H
Total Required Fall Clearance
Including sub-total E and Swing Fall F (from Chart 2)
Figure 6 - Calculating Minimum Required Fall Clearance SRL-LE
* If a potential Swing Fall Hazard condition is also present, additional Fall Clearance is needed in the
above calculation; see Chart 2 on the following page for calculating this additional required distance.
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