bricks, cable protecting caps (clay,Underground Cable Construction. soil resistivity (K3) Derating factor formula = Cable current * K1*K2*K3*K4…*Kn, While K’s are the derating factors of the cable. Insulation electrical strength approx 10: 16: Ohm x cmDucting for electricity cables is rigid and held within black protective tubing. water, BT, TV cables, drains, etc. 1. Alberta Electrical Utility Code, 6th Edition, 2022 Declared in force on September 1, 2023. 75mm - 50Mtr Coil; Coil Dia: 1. 10. However, you should discuss the application of this information in respect of any use of the land with the local electricity company. This can be achieved by a safe system of work based on planning, use of plans, cable locating devices and safe digging practices. Solar Cable PV1-F in ducting underground. The advantages of thermoplastic ducts are: Do not corrode. 2 Earthing ArrangementsGeneral purpose ducting (Daviduct) is a cost effective alternative to higher specification systems for use in general light and medium duty applications. "Cover" refers The reason each pipe is a different colour is purely for safety reasons and to identify which ducting is protecting which type of cable. Loop high voltage feeders around the inside of the manhole tied to the insulators. In case of a dispute, the duct and optical cable manufacturer’s procedure shall apply. Duct Pipe Cable Marker Systems Recommended Minimum Depths Carriageway Electricity HV (High Voltage) red duct Black or or tile N/A Red or black Yellow with blackPlastic Utilities Duct for Underground Installations 3. Bends: Short radius and Long radius 22. The legal framework for health and safety at work is set down in a variety of legislation - Acts of Parliament, and Statutory Regulations. S. Ducts may be of stoneware, cement concrete. 9m 1. Cable to be well supported by firm bed of sand beneath the cable. UF cable can be direct-buried (without conduit) with a minimum of 24 inches of earth cover. Just imagine the condition of overhead wires after a severe storm, all torn, damaged, and tangled. Easy to assemble, cut, and drill. 1 of 2. 8 handling of cables 19 6. 2. It is therefore no surprise that general electrical installations, accessories and equipment for use within the EU, and their associated harmonised standards, have been developed with these supplyDiscuss Sealing underground ducting in the Electrical Wiring, Theories and Regulations area at ElectriciansForums. 2m 2. 8, 300. Hubbell offers a comprehensive offering of steel and aluminum duct products. 289 products. IEC 60183: Guide to the selection of high -voltage cables. Buy Cable Ducting products and get the best deals at the lowest prices on eBay! Great Savings & Free Delivery / Collection on many items. , the second largest electric utility in the country, said it was working on moving power cables underground in selected areas in Cebu to do away with the. Most of them are related to the mistaken notions about the ways of burying THHN/ THWN electrical. g. That’s why it’s so important to pick an. 128 shall apply to all underground electric supply and communication systems coming within the jurisdiction of this Commission, and shall be effective on December 1, 1967. Choosing trees to plant near underground utilities. Class 3 twinwall ducting with a smooth internal bore and a corrugated external profile making it suitable for cable management systems. Schedule 2 of The Electricity Safety, Quality and Continuity Regulations 2002 gives the ground clearances for different types of line. It’s a lightweight material that shouldn’t be placed in direct sunlight because of its low UV stability. Flexible conduit is a form of routing and securing wiring which retains pliability in movement. 5 TRENCH LAYOUT 12 3. Recommended Positioning of Utility. 10. Browse our range of utilities & services such as ducting for providing protection for pipes or cables in the ground. £19. £6. 75 mm. This method requires digging a 1. Furnish and install a “Danger – High Voltage” sign at each manhole, cable chamber, junction box, pull box, and vault. 3. It's typically offered in a variety of materials although. Naylor General Purpose Black Cable Duct 45º Bend. Laying of engineering networks. 1 Cables must be suitable for laying direct in the ground, in concrete cable trenches, conduits, exposed cable ducts, in the open, on ladders, trays, exposed to direct sunlight, or immersed in water for extended periods. The cables are laid in the trench and covered with a 10 cm thick layer of sand. All ducts shall be indelibly and clearly marked with the legend ‘ELECTRIC CABLE DUCT’ the Class of duct and the manufacturers name or reference number in accordance with ENA TS 12-24. 4 U/G cable found in shallow cover 33 5. -insulated cables to Table 6 of B. FIG 3 Rubber double insulated 2 core cable - HO7RN-F 2 cable Cable Ducting Electric (PE) pipe. 128 attached hereto be and it hereby is adopted. These clearance distances are for along the entire length of the service pipe and must be taken into account when the trench is being excavated. (2) M identifies either the mid-wire of a three-wire DC circuit, or the earthed conductor of a two-wire earthed DC circuit. 6: “Sealing of conduits after cables, etc. Underground ducts of rigid metallic steel conduit, Schedule 80 PVC conduit, or equivalent, containing cables operating at a potential above 35,000 volts, shall be installed at a depth of at least 36 inches. We always think ahead, being one. 2. For cables in commercial parks on in areas where underground cables are routinely installed in duct, meeting these requirements may require cutting into the duct if the. Code of Massachusetts Regulations. Equipment that produces, modifies, regulates, controls, or safeguards a supply of electric energy. 1. g. 2: '4. Unarmoured cables in 750N dual-walled ducts ('twin wall') to BS EN 61386-24 should be OK. 42 Ex VAT. See Regulation 522. 5 Draw-in Pit B3. 5 Siting of Distribution & Supply Equipment 5. The National Electric Safety Code section 32 Table 352-1 indicates the minimum depth for Direct Buried, Single Duct or Duct Bank. Protect wiring from impact and the environment in runs indoors, outdoors, and underground. Corrugated exterior for strength. • Footpath or service strip ducting must be laid at a minimum of 250mm depth of cover. High resistance to corrosion. Said General Order No. We are pioneers in the field of manufacturing and supply of all kinds of identification labels, Pipe Marking tapes, Duct Labels, Electrical. 45m wide trench which is then covered with a layer of sand. 7 is dedicated to separations between underground cables and between underground cables and a wide range of underground installations, such as communication systems, pipelines, tanks, structures, ducts, etc. Features & Benefits: Naylor MetroDuct Underground Electric Cable Ducting Coil - 50m. For use with electric cables. power and telecom cable. Find many great new & used options and get the best deals for Electric Cable Duct Ducting 32mm or 38mm ID x50m Smooth Bore Coil Black / Hockey at the best online prices at eBay! Free delivery for many products!. In this system, small and large cables can be used together, however, its dependency on the number of these cables is restricted through the wiring regulations. underground power cables, and to a limited extent to overhead lines that may form a part of an FAA-owned circuit. the requirements of the Canadian Electrical Code and BC Hydro’s standards as follows: 1. 22 meters (4 feet) in depth. The duct must have. Wall and trench duct is heavily utilized in the healthcare industry. For example, a maple tree that stands 15 feet tall has roots that spread 15 (or more!) feet in both directions. Class 2 - Ducts for underground cables between 230V and 20kV (including LV services) and pilot and. Class 2 - Ducts for underground cables between 230V and 20kV (including LV services) and pilot and. Manufactured from polyethylene. 2 U/G cable found damaged 33 5. (ii) Requirements revised that dimensions of the cable duct to be agreed between the specifier and manufacturer. In the case of single core cables, within the metallic. This is done not for interference but to prevent eddy current heating. the cable may be subject to similar damage in other locations. 67 £20. Click and Collect is available or enjoy free UK delivery on selected orders over £150 excl. problems of installation can be avoided by designing cable layouts within the installation limits of this recommended practice. To meet the intent of Rule 12-604, armoured cable located in areas where the cable may be subject to mechanical damage from vehicles or equipment must have mechanical protection for 2 m above grade. Smooth internal bore to prevent tugging of cables. Available in various sizing options. Projected number of cables assuming 1800 pairs of cable will be placed: 15000/1800 = 9, which requires 9 conduits. Step 6 – Preparing a 50mm deep bed of sand or fine soil in the base of the trench. 77, Then multiply this value by the cable current. 3 (A)] TABLE E3801. 7. At least modulo the 1/4" or so distance between the conductors. For standards pertaining to. 90° bend with a 150mm inner diameter and 178mm outer diameter. The ducts are appropriately marked, in accordance with the customer’s requirements. contained underground electrical cables. A quick guide to Underground Ducting. 2 Dargan Depot (Belfast)Cable Ducting – pipes-underground. I've had little luck finding out what's required so far through. Article 507. Enter postcode for local availability. 3. Heavy load performance RED-E-DUCT products are engineered to withstand . Class 2 power ducting is for low voltage applications (230v/11kV & 20kV with 450kN compression performance at operating temperatures of 50°C). Cables shall also be numbered where they branch off from a main route. 5m, but if loaded up to the maximum you will get some volt drop, plus a 4mm. 2. The use of plastic cable ducts or tubes is prohibited. To protect against mechanical injury the trench is then covered with bricks and other materials. (i) Requirement added that cable ducts dimensions shall be specified by duct ID unless otherwise agreed. or in cable ducts: If it is necessary to install any of these types of cable in an in-air environment (i. Protection of Conductors and Cables A review of Rule 12-012(5) indicates that it is intended to apply to cables other than armoured cable, mineral-insulated cable and aluminum-sheathed cable. Straight joint Breech joint Pot end Main Service Joint 1. in concrete and underground. 1 of C22. 1Mtr x. A lightweight, high strength Twin Walled main duct system providing excellent protection for electrical cables when installing through walls and for fast underground installation. 1 Construction (Design and Management) Regulations (CDM) 5 2. 3 Doubt about identification of cables amongst different 33 utilities 5. VAT. Soil & Vent 60; Access Covers & Gratings 27; Building Steel 13;. MIPATEX DWC pipes are made from the best available HDPE raw material with a very high life expectancy, which is more than 50 years in some cases. Features & Benefits: Underground Twinwall Electric Cable Ducting 150/178mm x 6m BlackApril 29, 2014. C. It is intended to provide guidelines in relation to any work in the vicinity of underground or overhead lines (OHL) electrical cables, and improve communication between DEWA and its stakeholders. Prewired conduit, or armored cable, offers an all-in-one solution with the wires already running through it. The minimum depth measured vertically to the top the project proponent shall ensure that underground services and. 2. Coil Weight: 14. Wire Sleeving. Loop the wires through the fish tape and wrap them with electrical tape. 2 in Appendix 4 to BS 7671:2018 (page 378), but note you should take into account the following correction factors using the expression if Equation 2 in item 5. 1 PB NJUG Guidelines on the Positioning of Underground Apparatus for New Development Site. See Regulation 522. Most purchases from business sellers are protected by the Consumer Contract Regulations 2013 which give. Back in 2013, the Visayan Electric Co. for use in cable ducting. Lightweight and easy to install. Hard objects can damage conduits, and even tiny fractures can let water in. direct buried conduit chapter 2. 3. An underground power cable is under the ground and so maintenance costs are quite less as the wire is safe from potential damage. Some water authorities allow MDPE to be laid at a shallower depth, depending on circumstances, but must. Class 1 power ducting is for high voltage applications (33kV, 66kV & 132kV with 450kN. but even that needs a depth a dam sight more than 4 inches!!!. Cable numbers shall be marked on the cables along their routes and at both termination points. Flame-resistant and self-extinguishing. UPVC Cable Duct Pipes DUCT Pipes are manufactured as per DIN 8062 and BS 3506 standards. 5mm waste pipe as a makeshift conduit running cables from the attic through the walls. This offers long-lasting protection and makes it a popular choice for many. 2. Title 220 CMR 126. APPLICABILITY These guidelines apply to all public and private underground utilities, including, but not limited to, electric power, communications (e. electrical cables when installing through walls and for fast underground installation. Install direct-bury Type UF-B cable. One of the main dangers which may arise when digging is that of possible injury from underground power cables. 28 states that;The cost to the developer of installing underground wiring in a 12-lot subdivision was almost three times the installation cost in a 48-lot subdivision, he reported. Twinwall Utility Duct Bend - 90 Degree x 125mm For All Colours. Protect wiring from impact and the environment in runs indoors, outdoors, and underground. Any. 3. 1 General B3. Size 125mm. 450mm is a generally recommended minimum and 600mm if the ground is likely to be disturbed. Bottom of excavation to be 300mm below top of cable or duct. All underground service conduits must be drained at the building entrance as per the BC Electrical Code. Flexible Conduit Ducting: Navigate intricate installations with ease using flexible conduit ducting. ELECTRICAL SUPPLIES AND WIRING SYSTEMS IN EXPLOSIVES BUILDINGS 5. Rigid metallic conduit is most often used in commercial applications. Duct Material: High Density Polyethylene (HDPE) This 94mm ID / 110mm OD twinwall ducting comes in a 50mtr coil with a factory fitted drawstring, complete with one coupler to connect multiple. 1. 3 SPEN Documents. For the sake of this test, let us say our configuration is exactly like DET6 below, that we can use an ampacity table which is handy:The reports are still available and can be purchased here. 150/178mm Electric Cable Ducting – 6m (Pack of 4) 150/178mm Electric Cable Ducting – 6m (Pack of 4) Featured Products. AS 5488-2013 Classification of subsurface utility. Hope this helps. 10. 37. net. See electric cable duct stock video clips. 2 U/G cable found damaged 33 5. being introduced into the duct. Underground wiring can be encased in concrete to reduce the burial depth. AS 4799-2000 Installation of underground utility services and pipelines within railway boundaries . . B Metering Equipment Clarified 480V, 2 wire service to indicate that it applies to meteredDirect-burial cable is a type of cable designed to withstand direct exposure to the soil and moisture and is rated for wet, dry, and damp environments. Unarmoured cables in 750N dual-walled ducts ('twin wall'). LV electrical cables and communication cables. Aug 1, 2011. Underground Cable Laying Method Statement. What Precautions Are Needed When Backfilling? Where a. Choose from top trade brands. Clause 8. Where, in a roof space, electrical cables can be stood on, a suitable form of covering is required to prevent the electrical cables from being damaged. The customer service conduit or duct must be gray, 75 mm (3 inches) in diameter, rigid DB2 PVC. 1 Insulating underground cables 04 2 Capital costs for installation of 05 underground cables 3 Underground cable technologies 06 4 Planning and environmental issues for 08 underground cables 5 Land use restrictions over cable routes 09 6 Operation, maintenance, refurbishment 10 and up-rating cables 7 Cable installation methods 11Discuss Trench Depth for underground cable. BUT you need to make sure: water can't build up in there, as most cables (even. 00. Alberta Electrical Utility Code. “Seal all underground conduits to prevent gases and water from entering the building or other MHs via the ductbank. Underfloor duct is ideal for hotel, retail, casino, and convention center applications. Daviduct is manufactured to traditionally accepted dimensions but do not. Unlike SWA cable 12v 2 core cable is not steel wire armoured and therefore rodents can chew into 2 core cable in the ground. e. 10. At bends the bending radius shall not be less than that specified by AS/NZS3000, AS3008 or the manufacturer’s recommendations. Series code: HSG47 (Third edition) Download a free copy (PDF) Buy this product. If more than one cable is required to be laid. As low as £5. 00 incl VAT. Direct laying. 1 Electrical Distribution Within Explosives Areas 4. 8 Section 35. Electric cable duct underground polypipe civils ltd 10. 50 incl VAT. Please make sure you provide a draw wire or rope within the laid ducting so that we can pull the cable through. Many EU countries have operated similarly-rated public supplies for more than 50 years. Easy to handle and install due to lightweight structure. Underground Cables: Electric power can be transmitted or distributed either by overhead system or by underground cables. 00. 9. It also must be PLTC-rated which includes passing the UL 1685 flame test. • Electric ducts are installed at the correct depth and position in accordance with the current version of the SWUK Guidelines on the Positioning and Colour Coding of Underground Utilities Apparatus, Volume 1, 29 October 2013. ‘Electric Cable Duct’. splices chapter 4. 1 JULY 1990 TO IS : 1255 -1983 CODE OF PRACTICE FOR INSTALLATION AND lVlAIN1'ENANCE Of' POWER CABLES UP TO AND INCLUDING 33 kV RATJNG ( Second Revision ) ( Page 7, clause 4. Smooth internal bore to prevent tugging of cables. Underground Ducting; Black Electric Cable Ducting; Class 3 Power Cable Ducting; Class 3 Power Cable Ducting. An organization responsible. IEC 60447: Basic and safety principles for man-machine interface, marking andNeutral or mid-wire(4) N or M Blue NOTE: (1) Power circuits include lighting circuits. 50mm Twin Walled Cable Duct Black. com Abstract: The design, installation, and protection of wire and cable systems in substations are covered in this guide, with the objective of minimizing cable failures and their consequences. 2 address these requirements. 1 This procedure applies to the installation of Superior Essex fiber optic cable into an underground duct system using either a pulling method or an air blowing method. It also applies to Extra Low Voltage (ELV) ranges and Low Voltage (LV. Wiring Ducts Information. GAVINBAYLISS 10 months ago. At MKM Building Supplies, your local building materials supplier, we have everything you need for your next construction or domestic project. In some cases the bedding layer of sand may be reduced to increase the depth of cover, however when laying cables direct a smooth surface must still be provided. electrical cable ductingHigh Voltage (HV)Medium Voltage (MV)Low Voltage (LV) applications with cables operating at 11kV, 33kV, 66kV and EHV up to 132kV. They are durable. Our highly cost-effective cable ducting products provide top-quality solutions for civil engineering, contracting, groundworks, and house-building projects. Section 9. Feed the fish tape through the conduit. High resistance against to and UV radiation. PVC conduit is threaded and comes in numerous thicknesses. IEC 60445: Identification of conductors by colours or numerals. This guidance is aimed at all those involved in commissioning, planning, managing and carrying out work on or near underground services. 41. Ensure you leave sufficient slack for corners, as well as for the depth it will need to be buried, or the length needed to run it up a wall. 5m deep and 0. Wiring ducts are rigid trays typically used as raceways for cables and wires within electrical enclosures. Duct: A closed passageway formed underground or in a structure and intended to receive one or. c. Black colour for clear identification. 1. S. Wire color. 7, in addition to Table 22 for 250-volt grade cables as seen in Figure 4, this would have been to accommodate the thickness of the. ENG. Steel wire armoured (SWA) cable is a type of hard-wearing, reinforced power and auxiliary control cable. All cables running underground must be installed in ducts with ECC in separate duct. Direct-burial cable is a UL rating earned once a cable passes insulation water absorption and crush-resistance tests. General design requirements outlined for new residential subdivisions, CBD projects,Electroplast Dutchclamp Coverall Two-Part Cable Duct is a practical solution for optimal protection and identification of cables and wires! View Product. 5m underground chambers, that flooded. Almost anything can be used as the conduit will protect the cable from being pierced or being corroded. The illustrations below outline the most common circumstances leading to contact with live electricity cables. Six inches Install galvanized rigid metal electrical conduit with individual insulated wires six inches deep. Street Works UK Guidelines on the Management of Third Party Cable Ducting: VOLUME 4: Street Works UK Guidelines for the Planning, Installation and Maintenance of Utility Apparatus in Proximity to Trees: Street Works UK 10:. The use of a proprietary cable pulling lubricant is required to reduce the risk of friction damage. Ducting. In the event of crossing or proximity of underground telecommunication cables and underground power cables, a minimum clearance of 100 mm shall be maintained, or the requirements according to (i) or (ii) shall be fulfilled: (i) A fire-retardant partition shall be provided between the cables, e. v. S. Yellow – Gas, oil, steam, petroleum, or other flammable material. Step 7 – Installing the ducting efficiently with as few bends and minimum waste as possible. %PDF-1. Browse by Population Size, Brand & more Hide Filters Show Filters Other In Stock (14) Class 3 power ducting is for general applications (450kN compression performance at operating temperatures of 23°c). The supplementary Department for Business Enterprise & Regulatory Reform Have you ever wondered what is underground cable ducting? Perhaps you’re curious about where it’s used or why there are so many types and colour variations of electric. water, BT, TV cables, drains, etc. 9 MB) 062111 Application of Underground Distribution Transformers (PDF, 233 KB) 062288 Underground Conduits (PDF, 630 KB)3 Apr 2012. For use with electric cables. Pipes or ducts are laid in the ground with manholes or suitable possessions along the cable route. 202 of BS 7671:2018, states that wiring systems shall be supported such that they will not be liable to premature collapse in the event of a fire. Product Details. Install a metal lined, plastic, 6" wide warning tape 18" above all raceways and duct banks. •. Most codes require that all electrical conduits be buried at least 12 inches deep for the house, garage, or building entrances. Marker Tape 24 3. It helps in wildfire prevention and in. £270. Following large-scale power outages, like the storm that hit B. net. • Cannot occupy a cabinet, outlet box, panel, or similar enclosure housing the electrical terminations of an electric light, power, or Class 1 circuit — unless the nonconductive optical fiber cable is. Brand PBSL Group. Twinwall Cable Ducting Red (750n) 100/118mm x 6mtr Incl. The advantages of thermoplastic ducts are: Do not corrode. This can be achieved by a safe system of work based on planning, use of plans, cable locating devices and safe digging practices. Existing Cables Back˜ll to Local Authority standard Sand 75mm min. Schedule 2 of The Electricity Safety, Quality and Continuity Regulations 2002 gives the ground clearances for different types of line. and electrical contractors on how to prepare the site for the installation of mains and service cable. They are durable. Add to basket. Add to Basket. Normally, breadthwise trunks range from 2/3 inches x 2/3 inches to 9 inches x 4 inches (i. 2 Dargan Depot (Belfast)The common non-metal electrical conduits include PVC conduit and PVC-C underground power cable ducts. It does not always need conduit, but it can be run inside the conduit to add additional protection to any electrical system. Add to basket. 43. So, I'm looking to run a cable capable of 220V 50A (and I believe 3 phase) to my detached garage via underground cable/conduit. Install #4/o bare copper ground cable the length of the duct bank to be used to connect the manholes to grounding system. Cable / Duct Marker Warning Tape A length of plastic tape laid above the duct along its entire length indicating the presence of the duct below the tape. Self-lay - United UtilitiesThis document provides guidance and information for developers and self-lay providers who want to install water mains and services on new developments. When running a gas main supply pipe underground the HSE specifies it should be at least 750mm deep in a verge or road, but 600mm deep for a footpath. APPLICABILITY These guidelines apply to all public and private underground. £130. 1Mtr x. Department 220 CMR - DEPARTMENT OF PUBLIC UTILITIES. Cable Duct 125mm (ID), 148mm (OD) Ridgiduct cable duct is suitable for underground cable ducting of low and high voltage power cables, this includes 400/1000 volt, 11kV, 33kV and triplex cables. Applying cable lubricant will make it easier to pull the cable. separate duct couplings to be marked where this is impractical. It must have the words ‘Electric Cable Duct’ stamped down the side so it’s easy for anyone coming across it to know exactly what’s inside. 2 It is the responsibility of all staff engaged in underground cable installation to comply with appropriate legislation. Abstract: The design, installation, and protection of wire and cable systems in substations are covered in this guide, with the objective of minimizing cable failures and their. 4 Cable Enclosed in Duct B3. Slope ducts to drain towards manholes and pullboxes, and away from building and equipment entrances. IEC 60287: Electric cables – Calculation of the current rating. The employer shall ensure. Underground Service Clearance for Swimming Pools. 00 - Underground Electric Supply And Communication Lines 50,000 Volts And Below. 2. e. It is one of a number of armoured electrical cables – which include 11 kV Cable and 33 kV Cable – and is found in underground systems, power networks and cable ducting. 2 Health and Safety Executive Publication HSG 47, ‘Avoiding Danger from Underground Services’ 5 3. 2. Prevent a. Depth 450mm. Sample of Schedule of Test Results for Electrical Wiring and Checklists 301 14. It meets ENATS 12-24 and BS EN 61386 specifications. 12. of wires and cables. 1 Supply to Buildings Containing Explosives 5. VIEW PRODUCT. (4) An earthed PELV conductor is blue. BS 7671 covers circuits supplied at nominal voltages up to and including 1000V AC or 1500V DC. g. In areas where cables are not easily accessed in a roof space, electrical cables will need some form of fixing by clipping or tying. Underground Drainage & Ducting; Category. Tech. For short cable runs such as this you could do well to provide a 50mm duct as Jason suggests. Colour: Black. Allowable wire and cable types and sizes are specified according to the circuit operating. Photos courtesy Electrical Safety Authority (ESA) By Patrick Falzon, C. 1. 4-way underground duct line is shown in Fig. FREE delivery Fri, 8 Sept on your first eligible order to UK or Ireland. f) Appropriate registration of Easements-in-Gross to the line owner’s requirements shall be provided by the landowners prior to livening for all electrical reticulation cables, service boxes and ducting on private property including right-of-ways. (ENATS) 12-24 coloured black and embossed ‘Electric Cable Duct’. Grey. Under the Electricity Safety, Quality, and Continuity Regulations 2002, all underground low and high voltage electricity cables must be installed into PVC cable ducting. Duct spacers shall be sized for the ducts being held, and shall provide the minimum spacing between ducts required forconcrete flow and by the NEC. 2. 05m for 22kV to 33kV cables. 1 LV Service Cablesoutdoor location in accordance with the National Electric Code. Minimum duct diameter D: D = 4Ca πk−−−√ D = 4 C a π k.