901.16 Construction Inspection Guidelines for Sec 901 - Revision history

Smithk: updated archaic link

2022-03-08T13:55:25Z

updated archaic link

← Older revision		Revision as of 08:55, 8 March 2022
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	The ''Engineering Policy Guidelines'' cannot cover every case that might arise. These instructions are intended to help the inspector cope with most installation problems. They are not necessarily given in the sequence a contractor may use in installation of such facilities.		The ''Engineering Policy Guidelines'' cannot cover every case that might arise. These instructions are intended to help the inspector cope with most installation problems. They are not necessarily given in the sequence a contractor may use in installation of such facilities.
	[[image:901.16.jpg\|left\|225px]]		[[image:901.16.jpg\|left\|225px]]
	Before the contractor commences any work, it is good practice to check with the supplying electric utility to determine whether location of the substation or control station and plan configuration of equipment thereon is satisfactory with them. This is done by [~~http~~://~~wwwi~~/~~design~~/~~default.htm~~ Design] while the project is in the design stage, but the utility sometimes has a policy change between time of design and actual construction which will affect the substation or control station. There have also been cases where supply voltage was changed or the supply line was moved to a different location in the interval between design and construction. Time and expense can be saved if the utility is again contacted for approval of contract plans before construction commences. Any change from the design agreement will require documentation by a letter from the utility company.		Before the contractor commences any work, it is good practice to check with the supplying electric utility to determine whether location of the substation or control station and plan configuration of equipment thereon is satisfactory with them. This is done by [https://modotgov.sharepoint.com/sites/DE/ Design] while the project is in the design stage, but the utility sometimes has a policy change between time of design and actual construction which will affect the substation or control station. There have also been cases where supply voltage was changed or the supply line was moved to a different location in the interval between design and construction. Time and expense can be saved if the utility is again contacted for approval of contract plans before construction commences. Any change from the design agreement will require documentation by a letter from the utility company.

	Check for overhead power lines that may not have proper clearance. Proper clearance is determined by the line to ground voltage of the transmission line. The power company will inform MoDOT of clearance needed. Vertical clearance shall be in accordance with [[643.3 Policy, Standards and Regulations#643.3.3 Definitions and General Information\|Vertical Clearance for Overhead Crossings]].		Check for overhead power lines that may not have proper clearance. Proper clearance is determined by the line to ground voltage of the transmission line. The power company will inform MoDOT of clearance needed. Vertical clearance shall be in accordance with [[643.3 Policy, Standards and Regulations#643.3.3 Definitions and General Information\|Vertical Clearance for Overhead Crossings]].

Smithk: Per TS, minor clarifications

2020-08-14T19:51:17Z

Per TS, minor clarifications

EPGsysop: Per TS, replaced LED wattage references with A,B and C nomenclature

2018-02-13T17:06:14Z

Per TS, replaced LED wattage references with A,B and C nomenclature

← Older revision		Revision as of 12:06, 13 February 2018
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	To calculate voltage drop of a circuit, line current and line resistance must be known. Then, by using Ohm’s Law, E = IR; where E = impressed secondary voltage, I = line current, and R = resistance of conductor cable, the voltage drop of any particular circuit may be calculated.		To calculate voltage drop of a circuit, line current and line resistance must be known. Then, by using Ohm’s Law, E = IR; where E = impressed secondary voltage, I = line current, and R = resistance of conductor cable, the voltage drop of any particular circuit may be calculated.

	For a sample problem that frequently occurs on a lighting project, assume the following data and circuit diagram. The circuit shown below is a typical multiple or parallel arrangement of ~~275 watt~~ LED luminaires using line-to-line voltage of 480.		For a sample problem that frequently occurs on a lighting project, assume the following data and circuit diagram. The circuit shown below is a typical multiple or parallel arrangement of LED-C luminaires using line-to-line voltage of 480.

	[[image:901.16 Schematic Wiring Diagram.jpg\|center\|700 px\|thumb\|<center>'''Fig. 901.16 Schematic Wiring Diagram'''</center>]]		[[image:901.16 Schematic Wiring Diagram.jpg\|center\|700 px\|thumb\|<center>'''Fig. 901.16 Schematic Wiring Diagram'''</center>]]

EPGsysop: Per TS, provided guidance to allow the use of LED luminaires for roadway lighting.

2018-02-09T23:38:58Z

Per TS, provided guidance to allow the use of LED luminaires for roadway lighting.

Show changes

EPGsysop at 19:21, 7 April 2017

2017-04-07T19:21:12Z

← Older revision		Revision as of 14:21, 7 April 2017
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	Before the substation is accepted, the supplying utility should make its hookup and install its metering equipment, if required. The utility will then either accept the substation as complying with its rules and safety codes, or will suggest minor changes with which MoDOT must comply. The contractor will be made aware that the utility’s requirements as well as those of MoDOT must be met.		Before the substation is accepted, the supplying utility should make its hookup and install its metering equipment, if required. The utility will then either accept the substation as complying with its rules and safety codes, or will suggest minor changes with which MoDOT must comply. The contractor will be made aware that the utility’s requirements as well as those of MoDOT must be met.

	In several areas in the state, MoDOT is not permitted to place a pole mounted control station. In these areas, a concrete base must be poured and the control cabinet mounted on top of the base. It is secured with four anchor bolts placed in the concrete base. The inspector will note that the neutral conductor is grounded by a ¾ in. x 10 ft. copper clad rod driven into the soil before the concrete base is poured. If rock is encountered and the ground rod cannot be driven to the proper depth, it is permissible to drive the ground rod in a location where there is no rock and run a No. 6 bare copper conductor from the rod through the base and attach it to the power company’s ground. If conditions are ~~such~~ that the rod cannot be driven within a reasonable distance of the base, then it is permissible to lay the rod horizontally on top of the rock and backfill. Driving or drilling a ground rod into solid rock does not provide an adequate grounding condition.		In several areas in the state, MoDOT is not permitted to place a pole mounted control station. In these areas, a concrete base must be poured and the control cabinet mounted on top of the base. It is secured with four anchor bolts placed in the concrete base. The inspector will note that the neutral conductor is grounded by a ¾ in. x 10 ft. copper clad rod driven into the soil before the concrete base is poured. If rock is encountered and the ground rod cannot be driven to the proper depth, it is permissible to drive the ground rod in a location where there is no rock and run a No. 6 bare copper conductor from the rod through the base and attach it to the power company’s ground. If conditions are so that the rod cannot be driven within a reasonable distance of the base, then it is permissible to lay the rod horizontally on top of the rock and backfill. Driving or drilling a ground rod into solid rock does not provide an adequate grounding condition.

	'''Trenching, Cable Conduit Installation And Backfilling (for Sec 901.10)''' This operation consists of excavating for the type of trench called for on the plans, placing one or more cable conduits unreeled from a cable trailer and backfilling the excavation in the specified manner. The above operation would seem to be one of few problems, however, Traffic informs us that repairing underground faults, shorts and grounds is one of the major expenses they have when maintaining highway lighting. Sharp rocks, broken glass and other sharp objects work their way through the plastic duct and the insulation and, in time, cause problems. In view of this potential problem, the inspectors are to inspect the excavation and the backfilling operation carefully. Even when the backfilling operation requires sand, it is always possible that objectionable material can be incorporated with the sand due to carelessness or inattention. Cable conduit is to be bent or kinked during installation to the point where the conductors cannot be easily pulled from the duct.		'''Trenching, Cable Conduit Installation And Backfilling (for Sec 901.10)''' This operation consists of excavating for the type of trench called for on the plans, placing one or more cable conduits unreeled from a cable trailer and backfilling the excavation in the specified manner. The above operation would seem to be one of few problems, however, Traffic informs us that repairing underground faults, shorts and grounds is one of the major expenses they have when maintaining highway lighting. Sharp rocks, broken glass and other sharp objects work their way through the plastic duct and the insulation and, in time, cause problems. In view of this potential problem, the inspectors are to inspect the excavation and the backfilling operation carefully. Even when the backfilling operation requires sand, it is always possible that objectionable material can be incorporated with the sand due to carelessness or inattention. Cable conduit is to be bent or kinked during installation to the point where the conductors cannot be easily pulled from the duct.

Smithk: updated link

2016-06-15T14:29:25Z

updated link

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	'''Conduit Systems.''' When cable is pulled through any conduit, the inspector checks the cable for abrasion and slashes as it emerges from conduit. Normally interior surfaces of a conduit are smooth but damaged ends can result in a rough or jagged surface that will slash the cable jacket as it is pulled. Specifications require that bushings be placed on conduit ends when cables are pulled into place. This will usually prevent any burrs or rough edges on conduit ends from damaging the cable. However, this will be carefully checked. Sometimes a rough edge has not been completely covered by the bushing, or a bushing may become loosened or displaced during the cable pulling operation.		'''Conduit Systems.''' When cable is pulled through any conduit, the inspector checks the cable for abrasion and slashes as it emerges from conduit. Normally interior surfaces of a conduit are smooth but damaged ends can result in a rough or jagged surface that will slash the cable jacket as it is pulled. Specifications require that bushings be placed on conduit ends when cables are pulled into place. This will usually prevent any burrs or rough edges on conduit ends from damaging the cable. However, this will be carefully checked. Sometimes a rough edge has not been completely covered by the bushing, or a bushing may become loosened or displaced during the cable pulling operation.

	Drains are required at low points of conduit systems located within a structure. Refer to [http://www.modot.~~mo.gov~~/business/standards_and_specs/~~Sec0707~~.pdf Sec 707.3.1]. Installation of drains or drain holes in junction boxes or conduits are to be given careful attention by the inspector. Failure to install or provide drains in conduit junction boxes and conduits can result in damaged cable and cracked structures due to water collecting in the conduits and freezing.		Drains are required at low points of conduit systems located within a structure. Refer to [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=11 Sec 707.3.1]. Installation of drains or drain holes in junction boxes or conduits are to be given careful attention by the inspector. Failure to install or provide drains in conduit junction boxes and conduits can result in damaged cable and cracked structures due to water collecting in the conduits and freezing.

	After the contractor has completed cable splicing, continuity checks, and resistance tests on circuits located in structures, the inspector confirms that all pull box covers are firmly fastened in place and sealed. Sealing is particularly important when the pull box is located in the sidewalk. Proper sealing eliminates the opportunity for surface water and deicing salts to enter the conduit system. A conduit system will always be subject to condensation; however, every attempt should be made to eliminate any possibility of surface moisture entering the system.		After the contractor has completed cable splicing, continuity checks, and resistance tests on circuits located in structures, the inspector confirms that all pull box covers are firmly fastened in place and sealed. Sealing is particularly important when the pull box is located in the sidewalk. Proper sealing eliminates the opportunity for surface water and deicing salts to enter the conduit system. A conduit system will always be subject to condensation; however, every attempt should be made to eliminate any possibility of surface moisture entering the system.

Smithk: "ensure" correction

2010-07-09T14:05:01Z

"ensure" correction

← Older revision		Revision as of 09:05, 9 July 2010
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	The resistance measuring instrument the contractor may use for making conductor cable insulation tests is a simple DC generator. This utilizes a hand operated crank to generate 500 volts. The contractor may choose to use a motor driven generator. The generator induces a potential of 500 volts between conductor and ground. Any weakness, nicks or cuts in insulation or any leaks in splices will create a current path through the insulation to ground. The generator scale is graduated in ohms to give a direct reading in resistance units. Other permitted resistance measuring devices may be battery powered.		The resistance measuring instrument the contractor may use for making conductor cable insulation tests is a simple DC generator. This utilizes a hand operated crank to generate 500 volts. The contractor may choose to use a motor driven generator. The generator induces a potential of 500 volts between conductor and ground. Any weakness, nicks or cuts in insulation or any leaks in splices will create a current path through the insulation to ground. The generator scale is graduated in ohms to give a direct reading in resistance units. Other permitted resistance measuring devices may be battery powered.

	'''Resistance Measuring Device (for Sec 901.14.1) ''' Before making insulation tests, the resistance measuring device, commonly called a “megger”, should be given 3 simple tests to ~~insure~~ reliable readings. These tests are performed as follows:		'''Resistance Measuring Device (for Sec 901.14.1) ''' Before making insulation tests, the resistance measuring device, commonly called a “megger”, should be given 3 simple tests to ensure reliable readings. These tests are performed as follows:

	:1. With no test leads connected to megger terminal, crank the instrument at a rate of at least 3 revolutions per second or until slip clutch starts to function. Since there is no current path across the terminals, indicator needle should read infinity.		:1. With no test leads connected to megger terminal, crank the instrument at a rate of at least 3 revolutions per second or until slip clutch starts to function. Since there is no current path across the terminals, indicator needle should read infinity.

Smithk: minor clarification

2010-04-16T17:40:01Z

minor clarification

← Older revision		Revision as of 12:40, 16 April 2010
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	'''Power Supply Asssembly (for Sec 901.8)'''		'''Power Supply Asssembly (for Sec 901.8)'''

	'''Substation And Control Station Erection.''' After the substation location has been approved by the supplying utility, the contractor may proceed with arming and erecting the substation pole. Since most substations are designed for step-down of a high voltage system to a 240/480 volt secondary supply, the main portion of this ~~section~~ covers inspection procedures on this type of substation. Erection of a pole mounted, secondary service control station and its inspection, however, will differ only to the extent that less equipment will be involved.		'''Substation And Control Station Erection.''' After the substation location has been approved by the supplying utility, the contractor may proceed with arming and erecting the substation pole. Since most substations are designed for step-down of a high voltage system to a 240/480 volt secondary supply, the main portion of this article covers inspection procedures on this type of substation. Erection of a pole mounted, secondary service control station and its inspection, however, will differ only to the extent that less equipment will be involved.

	The inspector will note that a minimum of dimensions is given on the standard drawing. None are given for spacing equipment on cross arms. Location of equipment on cross arms is not critical from the standpoint of actual weight or electrical safety. It is good practice, however, to have the contractor install the control transformer far out on the cross arms. Location of the distribution transformer on the opposite end of arms is to varied according to its weight. This will give a balanced condition for the equipment. If equipment is not balanced, the pole will, in a short time, start to bend toward the greatest load. If a cluster type mounting unit is specified in lieu of cross-mounting for the transformer and oil switch, only the height of cluster need be checked.		The inspector will note that a minimum of dimensions is given on the standard drawing. None are given for spacing equipment on cross arms. Location of equipment on cross arms is not critical from the standpoint of actual weight or electrical safety. It is good practice, however, to have the contractor install the control transformer far out on the cross arms. Location of the distribution transformer on the opposite end of arms is to varied according to its weight. This will give a balanced condition for the equipment. If equipment is not balanced, the pole will, in a short time, start to bend toward the greatest load. If a cluster type mounting unit is specified in lieu of cross-mounting for the transformer and oil switch, only the height of cluster need be checked.

Smithk: minor clarification

2010-03-30T18:27:20Z

minor clarification

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	'''Description (for Sec 901.1)'''		'''Description (for Sec 901.1)'''

	'''Definitions.''' Refer to [[901.15 Glossary\|901.15 Glossary]] for definitions of terms and equipment used in highway lighting work.		'''Definitions.''' Refer to [[901.15 Glossary\|EPG 901.15 Glossary]] for definitions of terms and equipment used in highway lighting work.

	'''List Of Equipment And Materials.''' Each proposal containing highway lighting has a list of equipment and material, which the contractor is required to submit to MoDOT before work commences. On this list the contractor indicates trade names and catalog numbers of the items he proposes to install. Since Project Operations-Materials does not have personnel or test facilities to perform electrical tests on this apparatus the list provides MoDOT the information needed for a check against the specifications.		'''List Of Equipment And Materials.''' Each proposal containing highway lighting has a list of equipment and material, which the contractor is required to submit to MoDOT before work commences. On this list the contractor indicates trade names and catalog numbers of the items he proposes to install. Since Project Operations-Materials does not have personnel or test facilities to perform electrical tests on this apparatus the list provides MoDOT the information needed for a check against the specifications.

Smithk: article construction

2009-07-21T15:31:53Z

article construction

← Older revision		Revision as of 10:31, 21 July 2009
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	Before the contractor commences any work, it is good practice to check with the supplying electric utility to determine whether location of the substation or control station and plan configuration of equipment thereon is satisfactory with them. This is done by [http://wwwi/design/default.htm Design] while the project is in the design stage, but the utility sometimes has a policy change between time of design and actual construction which will affect the substation or control station. There have also been cases where supply voltage was changed or the supply line was moved to a different location in the interval between design and construction. Time and expense can be saved if the utility is again contacted for approval of contract plans before construction commences. Any change from the design agreement will require documentation by a letter from the utility company.		Before the contractor commences any work, it is good practice to check with the supplying electric utility to determine whether location of the substation or control station and plan configuration of equipment thereon is satisfactory with them. This is done by [http://wwwi/design/default.htm Design] while the project is in the design stage, but the utility sometimes has a policy change between time of design and actual construction which will affect the substation or control station. There have also been cases where supply voltage was changed or the supply line was moved to a different location in the interval between design and construction. Time and expense can be saved if the utility is again contacted for approval of contract plans before construction commences. Any change from the design agreement will require documentation by a letter from the utility company.

	Check for overhead power lines that may not have proper clearance. Proper clearance is determined by the line to ground voltage of the transmission line. The power company will inform MoDOT of clearance needed. Vertical clearance shall be in accordance with [[643.3 Policy, Standards and Regulations#643.3.1.3 Definitions and General Information\|Vertical Clearance for Overhead Crossings]].		Check for overhead power lines that may not have proper clearance. Proper clearance is determined by the line to ground voltage of the transmission line. The power company will inform MoDOT of clearance needed. Vertical clearance shall be in accordance with [[643.3 Policy, Standards and Regulations#643.3.3 Definitions and General Information\|Vertical Clearance for Overhead Crossings]].

	On projects where 45 ft. mounting height poles are specified, clearance from overhead primary lines is especially important since the higher poles will place them nearer high voltage conductors (above 2.3 kilovolts). When high voltage comes in contact with a steel or aluminum pole most of the current will go directly to ground. However, there is generally enough over-current to damage the luminaire, the pole and bracket cable and occasionally the control cabinet and its contents.		On projects where 45 ft. mounting height poles are specified, clearance from overhead primary lines is especially important since the higher poles will place them nearer high voltage conductors (above 2.3 kilovolts). When high voltage comes in contact with a steel or aluminum pole most of the current will go directly to ground. However, there is generally enough over-current to damage the luminaire, the pole and bracket cable and occasionally the control cabinet and its contents.