UGANDA STAND ARD  
  DUS 2264  
First Edition  
2020 -07-22 
 
 
 Reference number  
DUS 2264 : 2020 
© UNBS 2020   
  
Stay blocks and cable concrete cover - Specification  
 UGANDA STANDARD  DUS 2264 : 2020  
 
© UNBS 2020  – All rights reserved  1 
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible fo r its correct application  
© UNBS 2020   
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photocopying and microfilm, without prior wri tten 
permission from UNBS.  
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
Kampala  
Uganda  
Tel: +256 41 4 333 2 50/1/2/3  
Fax: +256 41 4 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 2264 : 2020  
2 © UNBS 2020  – All rights reserved  
 Contents   Page 
Foreword  ................................ ................................ ................................ ................................ ................. 3 
1 Scope  ................................ ................................ ................................ ................................ .......... 1 
2 Normative references  ................................ ................................ ................................ .................. 1 
3 Terms and definitions ................................ ................................ ................................ .................. 1 
4 Requ irements  ................................ ................................ ................................ .............................. 1 
4.1 Operating Conditions  ................................ ................................ ................................ .................. 1 
4.2 Design and Construction ................................ ................................ ................................ ............. 2 
4.2.1 General  ................................ ................................ ................................ ................................ ........ 2 
4 2.2  Dimensions  ................................ ................................ ................................ ................................ .2 
4.3 Marking ................................ ................................ ................................ ................................ ........ 3 
5 Tests ................................ ................................ ................................ ................................ ............ 3 
5.1.1  Transverse strength test for unreinforced concrete cable cover ................................ ................. 4 
Annex  A (Informative)  Information (in case of tender award)  ................................ ................................ .5 
Bibliography  ................................ ................................ ................................ ................................ ............ 7 
 DUS 2264 : 2020  
© UNBS 2020  – All rights reserved  3 
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade , Industry and 
Cooperatives established under Cap 327 , of the L aws of Uganda , as amended .  UNBS is mandated to co -
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT  Agreement  of the World Trade Organisation (WTO).  
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and  consists of key stakeholders 
including government, academia, consumer groups, private sector and other interested parties.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments . The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
The committee responsible for this document is Technical Committee UNBS /TC ###, [name of commit tee], 
Subcommittee SC ##, [name of subcommittee] . 
This second/third/… edition cancels and replaces the first/second/… edition ( US nnn-n:yyyy ), which has been 
technically revised.  
 DUS 2264 : 2020  
4 © UNBS 2020  – All rights reserved  
  UGANDA STANDARD  DUS 2264 : 2020  
 
© UNBS 2020  – All rights reserved  1 
 Stay blocks and cable concrete cover – Specification  
1 Scope   
1.1 This s pecification is for concrete products for use on power lines.  
1.2 The specification covers the following concrete products:  
a) Slab, LV  
b) Slab, HV  
c) Stay block, 19mm  (3/4")  
d) Stay block, 25mm  (1"). 
2 Normative references   
The following referenced documents referred  to in the text in such a way that some or all of their content 
constitutes requirements of this document. For dated references, only the edition cited applies. For undated 
references, the latest edition of the referenced document (including any amendments ) applies.  
ESI 43, Stay Strands and Stay Fittings for Overhead Lines  
US EAS 412 -3, Steel for the reinforcement of concrete — Part 3: Welded fabric   
US ISO 19595, Natural aggregates  for concrete  
US EAS 18 -1, Cement — Part 1: Composition, specification and c onformity criteria for common cements . 
3 Terms and definitions   
ISO and IEC maintain terminological databases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp  
3.1 
 
4 Requirements  
4.1 Operating Conditions  
4.1.1  The concrete products shall be suitable for use in tropical conditions at altitudes of up to 2  200m 
above sea level, temperatures of -1 to 40 oc and humidity of 95%.  
4.1.2  The stay block shall be buried at depths of up to 1.8m i n soils of various types to act as an anchor for 
stay wire on overhead lines.  DUS 2264 : 2020  
2 © UNBS 2020  – All rights reserved  
 4.1.3  The cable covers shall be laid above power cables buried underground in soils of various types. High 
voltage cables are buried at depths of up to 1.6m while low voltage cab les are buried at depths of 0.5m.  
4.1.4  The concrete stay blocks designated 19mm ( 3/4") shall be used with stay rod size  2438.4 mm x 19mm  
(8ft x 3/4" ) of 64kN minimum failing load while those designated 1" shall be used with stay rod size  2743.2 mm 
x 25mm  (9ft x 1 ") of 131. 6kN minimum failing load.  
4.1.5 The cable covers designated LV shall be used to cover cables operating at 240/415 V (low voltage) 
while those designated HV shall be used to cover cables operating at higher voltages up to 66kV.  
4.2 Design and Construction  
4.2.1  General  
4.2.1.1  The pr oducts shall be made using Portland cement conforming to US EAS 18 -1, course 
aggregates not exceeding 10mm nominal size and conforming to US ISO 19595 , clean river sand and drinking 
quality water free from any visual contamination.  
4.2.1.2  The products sha ll not contain additional admixtures and pigments. The composition of cement, 
sand and course aggregates shall be such as to satisfy the requirement for transverse strength and ultimate 
failing load.  
4.2.1.3  The concrete stay blocks shall be reinforced whi le the cable covers shall contain no steel 
reinforcement.  
4.2.1.4  Steel moulds shall be used in the manufacture of the products so as to ensure a smooth texture 
externally. The mould shall be accurately made to produce units of the dimensions, profiles and  shapes 
designed.  
4.2.1.5  The product shall be vibrated while on mould to ensure a dense mass free from honeycombs or 
segregation and fill the forms and spaces between reinforcement (for concrete slay blocks) compactly and 
without voids. The vibrator used shall have a frequency of not less than 5000 cycles/minute and shall not be 
attached to or allowed to touch reinforcement during compacting.  
4.2.1.6  Lettering shown on the drawings (for cable covers) shall be formed using accurately placed 
formers securely  fixed in position. Cutting either uncured or hardened concrete shall not be permitted.  
4.2.1.7  Freshly placed concrete shall be suitably protected and shall be kept constantly damp for a period 
of at least four days after concreting. The concrete shall be  allowed to dry slowly over a period of at least three 
days after wet curing is completed.  
4.2.1.8  Steel reinforcement rods shall be welded at all points of crossing and all dimensions shall be as 
per US EAS 412 -3. Alternatively, a welded reinforcing fabri c of  diameter  5.385  mm by 75 mm square  (No 5 
SWG  x 75 mm square ) with the wires symmetrically placed about the centre would be accepted  
4.2 1.9  The underside of the cable cover and stay block shall be flat while the upper sides shall be 
peaked as shown on drawings.  
4.2.1.10  The concrete cabl e cover shall have one end concave, the other convex (as shown in drawings) 
to provide a concave/convex Joint resisting lateral displacement.  
4 2.2  Dimensions  
4.2.2.1  The cable covers are required in two sizes with dimensions as shown in table 1 and figure s 1 and 
2 attached. Tolerances on length (L), width (W) and thickness at outer edges (H) shall be ±3  mm and ±2  mm 
respectively.  DUS 2264 : 2020  
© UNBS 2020  – All rights reserved  3 
 4.2.2.2  When tested in accordance with clause 6.1.1.1  the concrete cable covers shall withstand, without 
breaking the loads given in table  1. 
Table 1  Cable cover sizes and transverse s trength  
Category  Dimensions(L x W x H) mm  Average Breaking  Load (kg ) 
HV 610 x 230 x 50  750 
LV 305 x 150 x 40  300 
 
4.2.2.3  The concrete stay blocks are required in two sizes with dimensions as shown in table 2 and 
figures 3 & 4 attached. Tolerances on length (L),  width (W) and thickness at outer edges (H) shall be ±3mm 
and ±2mm respectively.  
4.2.2.4  When tested in accordance with ESI 43 - 91 the concrete stay blocks shall withstand, for a period 
of 1 minute, the ultimate failing loads given in table 2 below.  
Table 2  Concrete stay blocks - sizes and ultimate failing l oad.  
Cate 01  Dimensions(L  x W x H) mm  Ultimate failing load (kN)  
19mm  (3/4")  500 x 380 x50 65 
(25mm ) (1") 660 x 480 x 60  80 
 
5 Marking  
5.1 The upper side of each cable cover shall be marked longitudinally by means of impression  
5.2 Each cable cover and stay block shall carry an Impression or embossment of the manufacturer's 
name or identifying mark.  
5.3 The following information shall be m arked on the manufacturer's certificate supplied with the cable 
covers and stay blocks.  
 Name, trademark of manufacturer   
 The reference number  of standard to which the concrete product complies   
 Type of binder constituent (s) used   
 Dimensions of the product   
 Instructions  (all in English Language)  
 Batch Number  
6 Tests  
6.1 Tests for the concrete stay blocks shall be in accordance with ESI 43 -91 while cable covers shall be 
tested in accordance with clause 6.1.1.1  DUS 2264 : 2020  
4 © UNBS 2020  – All rights reserved  
 6.1.1 Transverse strength test for unreinforced concrete cable cover  
6.1.1.1  Procedure  
The cover sample to be tested shall be soaked in water at approximately 15 to 20°C for 24 hours immediately 
before testing and shall be  tested wet. Each cover to be tested shall be evenly supported upon two  self-
aligning steel bearers 50 mm in diameter, the distance between the  centres of the bea rers being 270 mm . The 
load shall then be  applied cent rally at a uniform rate of 9 000N/minute 10 percent through  a third steel bearer 
also 50 mm in diameter placed midway be tween the)  supports upon the upper surface of the cover and 
parallel to the supports.  
The length of all the bearers shall be more  than the width of the cover to be tested.  
6.2 Copies of previous type and routine test certificates certified by the relevant National Testing Authority 
of the country of manufacturer shall be submitted for Tender Evaluation.  
6.3 In the case of tender award certified test reports f or the concrete products to be supplied shall be sent 
for approval before shipment/delivery of the g oods. The test reports shall be certified by the relevant National 
Testing Authority of the country of manufacture.  
6.4 The Tenderer shall submit a clause by clause statement of compliance with these specifications. 
Relevant technical details including the  transverse strength, and ultimate failing load shall be submitted in 
support and shall be clearly marked to indicate the item and type reference numbers of the product offered.  
6.5 The manufacturer's declaration of conformity to reference standards, quali ty assurance certification 
and list of previous customers (utilities) shall also be submitted  DUS 2264 : 2020  
© UNBS 2020  – All rights reserved  5 
 Annex  A 
(Informative)  
 
Information (in case of tender award)   
Drawings and technical det ails shall be submitted for approval before manufacture of the co ncrete p roducts 
commences. U ndertakes to submit their comments or approval for the drawings within three weeks of 
receiving the daft copies.  
 
Fig:1 Concrete slab to cover cables  
 
 DUS 2264 : 2020  
6 © UNBS 2020  – All rights reserved  
 Fig:2  Concrete stay blocks . 
 DUS 2264 : 2020  
© UNBS 2020  – All rights reserved  7 
 Bibliography  
[1] TSP-07-001, Specification for Concrete Products (Stay Block s & Hatari Slabs)   
 DUS 2264 : 2020  
© UNBS 2020  – All rights reserved  9 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is governed by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The 
presence of this mark o n a product or in relation to a product is an assurance that the goods comply with the 
requirements of that standard under a system of supervision, control and testing in accordance with the 
certification mark scheme of the Uganda National Bureau of Standa rds. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 DUS 2264 : 2020    
 
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© UNBS 2020 – All rights reserved