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Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

September 30, 1991

Mr. Kelly Sears
Safety Director
Jensen Construction Co.
5550 N.E. 22nd Street
Des Moines, Iowa 50316-0345

Dear Mr. Sears:

This is in response to your June 3, letter in which you request the Occupational Safety and Health Administration (OSHA) to recognize the existence of a "hazardous position greater than that which existed before installing" an anti-two blocking device as required by 29 CFR 1926.550(g)(3)(ii)(c). We apologize for the delay in responding to your inquiry.

Before a "greater hazard" defense is recognized by OSHA, an employer must show, among other things, that there are no alternative means of employee protection. Your letter indicates that you have problems with a particular brand of anti-two blocking device and that repeated attempts to have the particular device redesigned have failed. However, there is no indication that other brands or designs have been used, nor is there a full showing of the events or reasons leading to the individual failures you mention. Consequently, based on the information received, it is not appropriate to recognize the existence of a "greater hazard", nor to suspend the requirements of .550(g)(3)(ii)(c).

If we may be of further assistance please call Mr. Roy F. Gurnham or Mr. Dale Cavanaugh at (202) 523-8136.



Patricia K. Clark, Director
Directorate of Compliance Programs


June 3, 1991

Gerald Reidy
Director of the Office of Construction
and Maritime Compliance OSHA
Room N-3610
200 Constitution Avenue
Washington, D.C. 20210

Dear Mr. Reidy:

As a result of a U.S. Department of Labor inspection at our project at Montainburg, Arkansas on May 16, 1990, Jensen Construction Company was issued a citation on June 6, 1990 for violating 29 CFR 1926.550(g)(3)(ii)(c). (See Attachment #1)

At that time, Jensen Construction Company contested the abatement period of June 12, 1990. The reason for contesting the abatement period was the availability of the anti-two blocking device from the distributor, Rector Equipment Company of Dallas. The devices were scheduled to be shipped from Rector Equipment Company on August 27, 1990. (See Attachment #2) However, the anti-two blocking devices were received on July 23, 1990 and installed on August 11, 1990.

After installing the devices, Jensen Construction Company had the anti-two blocking device fail. The cable holding the device in line with the cranes' hoisting cable was cut allowing the anti-two blocking counter weight to fall approximately 200 feet down the hoisting cable. The counterweight shattered at impact.

After discussing this problem with Rector Equipment Company and CraneTronics, manufacturers of the anti-two blocking device, Jensen Construction Company was under the impression that these were isolated instances. Therefore, Jensen Construction Company signed the settlement agreement on or about November 15, 1990 disposing of this matter prior to hearing.

Although the matter had been settled, we continued to have the anti-two blocking device fail. Under the guidance of American Crane Corporation, we tried different designs, i.e.: used a larger counterweight; a chain in place of a cable; replaced the cranes' hoisting cable with rotation resistant cable. None of these strategies have worked.

On November 19, 1990 Jensen Construction Company gave American Crane Corporation notice that we would no longer test different methods for use of the anti-two blocking device for them. (See Attachment #3)

To this day we are still experiencing anti-two blocking failures. So far during the month of May 1991 we have had a total of 13 failures on our projects.

Jensen Construction Company feels that the faulty design in the anti-two blocking device has created a greater hazard for our employees when it is in use than they would have without it's use. We have followed the manufacturer's guidelines and have tried other designs under their direction. We believe that the anti-two blocking devices should be disconnected while American Crane Corporation and CraneTronics correct the problems with the present device and supply us with a workable device. If they are not disconnected while this problem still exists, we are putting our workers in a hazardous position greater than that which existed before installing the anti-two blocking device.

Please give us your opinion on this matter and the direction we need to take.



Kelly Sears
Safety Director


Attachment 1 (For Attachment 1 see printed copy)


Attachment 2


Rector Equipment Co.,Inc.
11618 Hawn Frwy
Dallas, Tx. 75253
Attn: Mr. Howard Ponder

Ref: Your PO# P1644 Our SO# 134105 (anti-two blocking kits)

Dear Howard,

Thank you for your order for two of pt.# 1172003 and one of pt # 1172002 anti-two blocking kits for Jensen Construction Co. of Pine Bluff, Arkansas. Shipment of this order is scheduled for 8/27/90.

The (2) 1172003 kits are for (1) model 999 your 18134 and (1) model 9270 your 18144. The 1172002 kit is for model 5300 your 18139.



Larry Schroeder
Parts manager


Attachment 3


Mr. Allen Williams
The American Crane Corporation
202 Raleigh Street
P.O. Box 9012
Wilmington, North Carolina 28403

Dear Mr. Williams:

In connection with your recent telephone conversations with Jim Godwin and Ricky Turnbow in our Pine Bluff, Arkansas office I wish to summarize what steps we have taken to correct our problem concerning the anti-two blocking system.

The anti-two-blocking device as is utilized on the 9270 crane has been destroyed twice by it's inadequate design which does not preclude the counterweight from being entangled in the hoisting line, thereby severing the attachment cable or chain and free falling to the headache ball at which time it self destructs and spews the area with metal shrapnel. This is a very dangerous situation with 200 feel of boom in the cranes.

After the two failures we have been sent a larger mouth counterweight and are using 1/8" cable which attaches the weight to the A-2-B Switch. Also awe have changed the hoist line to rotation resistant cable.

We have cooperated with American Crane to solve this problem but if experimentation is required due to a faulty product the manufacturer needs to perform that function and not Jensen Construction Company.

Under the current regulations we are using the anti-two-blocking system on several cranes at the Frog Bayou project but we feel they place our personnel in danger.

We would like to hear your thoughts and comments on this subject.



Kelly Sears

Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.