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Suggested Wiring Procedures for an Overhead Temporary Service Pole (NEC 2002)

By Warren Goodrich
Suggested Wiring Procedures for an Overhead Temporary Service Pole (NEC 2002)

All 125 volt rated receptacles rated in amps 15, 20, or 30 that are installed on a temporary service pole or installed for use as temporary wiring must be GFCI protected (NEC Article 527.6.A). If all 125 volt receptacles installed on the temporary or installed for use as temporary wiring are on the same branch circuit, the GFCI protective device installed as the first receptacle on that circuit may protect be used as the GFCI protective device serving all other receptacles on that circuit attached to the load side of that GFCI protective.

Receptacle Style and Type

The lead receptacle on each circuit must be a GFCI receptacle with the other normal receptacles that are then GFI protected by that one GFCI protective device. You may use a GFCI breaker serving each circuit and also serving as the overcurrent device instead of the GFCI receptacle style protective device if you wish. Any direct connect circuit (connectors & wire nut style connection) is allowed not to be GFCI protected, until a receptacle appears on that circuit, then the GFCI protective device must appear when that receptacle appears Article NEC Article 527.6.A. If the branch circuit is direct connected, at the end of line, without any receptacle installed on that circuit, then no GFCI protective device is required. Code mute.

Any other type receptacle other than 125 volt 15, 20, 30 amp receptacles, no matter what amp or voltage rating, must also be GFCI protected or you must have a documented, recorded record showing the tests were done before initial use and every 3 months thereafter. These records must be presented to the Electrical Inspector upon his or her request (NEC Article 527.6.B). The requirements of other receptacles stated in NEC Article 527.6.B includes 40 and 50 amp receptacles or even 220 volt receptacles if not part of a permanent wiring system of a permanent structure.

Receptacle Box/Style and Type

All boxes on an overhead temporary service pole will be considered exposed to wet location. (See definitions in NEC Article 100). Therefore all boxes, fittings, and covers must be approved as weatherproof if surface mounted (NEC Article 312.2.A and NEC Article 314.15.A). The receptacles on the temporary must have a weathershield mounted over the box. NEC Article 406.8 This weather shield will look like a plastic cover you would find over a thermostat in a motel hallway, except the weathershield must be approved as weatherproof and approved for the purpose. This weathershield might be clear or opaque.

To view an example of a weatherproof device box and a weather shield , click onthe picture icon to the left.

 

If the any box is metal, you must bond the metal box to the grounding conductor. NEC Article 250.110 The bonding method may be accomplished by installing a green ground screw NEC Article 250.126 secured to a threaded hole in the back of the box. The bonding method of a receptacle may be accomplished by installing a self grounding receptacle approved for the purpose using the metal box as the grounding contact between the yoke of the self grounding receptacle NEC Article 250.146.B and the metal box if the box is surface mounted NEC Article 250.126.A using a normal receptacle mounting yoke. The previous rules applies if the box is with equipment grounding such as the box connected by an equipment grounding conductor to a green grounding screw NEC Article 250.126 or a metal conduit being used as an equipment grounding conductor bonding the metal box. NEC Article 250.118

You can identify a self-grounding receptacle by the spring clip mounted at the yoke, to insure an adequate contact to the box. NEC Article 250.146.B This type of self-grounding receptacle is commonly used on metal conduit wiring style often found on commercial project where no grounding conductor is ran, but instead this wiring style is using the conduit as the grounding path. NEC Article 250.118 The boxes must be securely mounted to the structure of the temporary. NEC Article 300.11.A

Pole Dimensions/Style/Type/Depth Requirements

The following requirements will not be found in the NEC, but these requirements will most likely be required by either the Utility Company rules, or the Authority Having Jurisdiction. The Authority Having Jurisdiction will use the NEC articles referring to the requirement that any permanent wiring style must be substantially mounted to a permanently installed structure. NEC Article 300.11.A You will find in the Chapter for temporary wiring that any electrical service is not considered as temporary but must be referred to NEC Article 230 for permanent service installations. NEC Article 527.4.A

In order to meet the minimum safety standards concerning wiring a service try the following link to our web site titled “Wiring a Service

A temporary overhead pole service is only a normal electrical service mounted on a pole. No less is required of a temporary pole service than a normal main dwelling service only smaller in amp rating and weatherproof.

The pole on an overhead temporary should be a minimum of 5" thick.

The total length requirement, generally is, approximately 16' long.

Special Note: If you opt for the 5' deep pole set without braces, then add 2' to the pole as described making the total pole length for the 5' deep pole set option of approximately 18' . The depth of the hole setting a pole must be at least 1/3 the length of the pole or be supported by braces.

"EXPLANATION" If you put 3' of post in the earth, [ braces are normally necessary on an overhead temporary if the pole is set to the 3' depth for the pole service ]. Mount your receptacle box [or boxes] on the bottom of the assembly starting approximately 2' 6”above finished grade - the receptacle assembly whether 1 receptacle or two receptacles should be taking up approximately 12" or space, then mount your disconnect or panel above the receptacle(s) - taking up approximately 1' 6", then mount your meterbase at 5' 6”above finish grade to center of meter, then run your rise up the post to 12' above finished grade level leaving the point of attachment at least 12' above finished grade. Then secure the riser to the pole by using a strap near the bottom {just above the meterbase} and then a strap at the top of the riser {just below the weatherhead}. You must supply a set of feeders approved for a wet location, and sized by the maximum amp rating of the main disconnect(s) used on the pole and able to reach at least 3' past the weatherhead into free air for the Utility Company' s connection., then you have used up approximately 16' for the pole length with a foot of pole to spare.

One example of an overhead temporary service may be viewed by clicking on the picture icon to the left.

Nipple Style and Type: Between Disconnect and Receptacles

When you come out of the bottom of the disconnect or panel, you will find your bossed [treaded] receptacle box conduit hole, laying offset from the hole at the bottom of your disconnect or panel box. You can usually resolve this offset condition where the holes don' t line up, by using an offset nipple. An offset nipple is like a short nipple with an “S”curve created when it is molded. The minimum size nipple, for a total number of conductors of three to nine 14 awg or three to nine 12 awg THWN conductors, which should be an adequate number for most applications from panel to receptacle paths, is 1/2". NEC Chapter 9, Table 1, Note 4. You could use a 1/2" offset nipple, this offset nipple, will usually make your "existing offset condition" work out, by twisting the offset 1/4 turn, to lessen the depth of offset adjustment needed, in order to meet your receptacle box bossed [threaded] hub out of line from your panel box knock out. The minimum size wire to your receptacles, through your offset nipple, from your over-current device [breaker or fuse], is 14 awg using a 15 amp maximum size overcurrent device. NEC Table 240.4.D The maximum size wire to your receptacles, through your offset nipple, from your overcurrent device [breaker or fuse], is 12 awg using a 20 amp maximum size overcurrent device. NEC Article 240.4.D and NEC 110.3.B [listing and labeling requirements.] The maximum wire size to a duplex receptacle is 12 awg on a 15 or 20 amp receptacle device. NEC Article 210.21.B.2 A 15 amp receptacle is allowed to serve a 14 awg -15 amp circuit and / or a 12 awg -20 amp branch circuit. NEC Article 210.21.B.2 Any form of receptacle must be and weather proof NEC Article 314.15.A. Any form of receptacle exposed to the weather must be with a weather shield. NEC Article 406.8.

An example of another weatherproof GFI protected receptacle with a bubble shield may be viewed by clicking on the picture icon to the left.

Any receptacle must be GFCI protected if on a temporary service pole or if 220 volt rated receptacle or receptacles rated more than 30 amp must be recorded on documented records made available to the electrical inspector upon request. NEC Article 527.6.A & B

An example of a 220 volt receptacle that must be GFI protected or provided with documented records of its use may be viewed by clicking on the picture icon to the left.

The conductors serving outside receptacles exposed to physical damage must be protected by the proper minimum nipple size required according to the size of the conductor being protected and the type of nipple being used.

Please keep in mind that any conductor 4 awg or larger must be protected with plastic bushings on the ends of the conduits. PVC is not exempt from the plastic bushing requirement for conductors 4 awg or larger. NEC Article 300.4.F

An example of a plastic bushing installed as required for 4 awg or larger conductors in a conduit may be viewed by clicking on the picture icon to the left.

Disconnects Size/Styles/Types/Minimum Sizes Per Circuits

Your overcurrent device [breaker box or fuse box] can be of an array of sizes, each size creating new requirements. I will attempt to approach the majority of your choices.

You must ensure that whichever panel you use to install as a panel used on a temporary service pole is a service rated panel. Some panels are not approved as a service rated panel but only allowed to be used as a non service rated panel [sub panel]. When building a service you must use a service rated panel that is listed and labeled as a service rated panel. When wiring a service rated panel the neutral bar and the grounding bar must be married together as well as containing a main bonding jumper to the metal of the main service rated panel or disconnect box.

To view an example of the inside wiring of a main service rated panel or disconnect you may view by clicking on the picture icon to the left.

If you use a type service panel limiting only one circuit in the box, you may use a minimum rating of 15 amps, weatherproof service rated panel. NEC Article 230.79.A

If you use a type service panel with only two circuits in the box, you must use a minimum rating of 30 amps, weatherproof service rated panel. NEC Article 230.79.B

An example of a two circuit service rated panel may be viewed by clicking on the picture icon to the left.

If you use a type service panel with more than two [three or more] circuits in the box, you must use a minimum rating of 60 amps, weatherproof service rated panel. NEC Article 230.79.D

You must use a service rated panel equal to or larger than the demand load calculated for your project as required by NEC Article 220 and NEC Article 230.79

It is allowed that if you have six or less [breakers or disconnects] {that are grouped}, a main disconnect, and / or, breaker is not required. NEC Article 230.71.A The number of breakers counted as main disconnects must not exceed 6 sweeps of the hand. The six maximum number of breakers may be either single pole or double pole breakers as long as it only takes six sweeps of the hand to just off all the main disconnect forms. NEC Article 230.71.B

Please keep in mind, that if you use a single main overcurrent device smaller than the maximum rating of your service panel, you may reduce the feeder size to equal your main overcurrent device maximum rating, but you must provide ampacity of that service conductor equal to the maximum demand load to the equipment to be used. NEC Article 220 and NEC Article 230.79

Please keep in mind, that although you are working with a "temporary", NEC Article 230 must still apply as a permanent service, and be treated as such. When it comes to services connecting to utility company point of connection there is no temporary wiring concerning that service until you are on the load side of that service panel after the branch circuit fuses or breakers.

Please keep in mind that any equipment being utilized as a service panel must be service rated as listed and labeled on that service rated panel' s label.

Nipple/Style/Type: Between Meter and Disconnect

Your nipple between the service panel, and the meterbase, must be sized by the feeder sizes which must be sized by the total of your service panel main over-current device/s maximum rating, or provide the maximum demand load of the equipment to be used on this service.

An example of a meter base connected by an offset nipple to a service rated panel may be viewed by clicking on the picture icon to the left.

If your service panel main over-current device size is 15 amps, you may use a feeder rated no less than a 15 amp rated conductor, from the transformer, through to the main lugs of the service panel, or the lug of your main over-current device depending on the service rated panel style that you plan to use. You may use 14 awg THWN between the riser and meter base and also between the meter base and the main service rated panel NEC Article 240.4.D The conduit minimum size for 14 awg would be ½”conduit no matter the type of conduit. NEC Appendix C

If your service panel main over-current device size is 30 amps, you may use a feeder rated no less than a 30 amp rated conductor, from the transformer, through to the main lugs of the service panel, or the lug of your main over-current device depending on the service rated panel style that you plan to use. You may use 10 awg THWN between the riser and meter base and also between the meter base and the main service rated panel NEC Article 240.4.D The conduit minimum size for 10 awg would be ½”conduit no matter the type of conduit. NEC Appendix C

If your service panel main over-current device size is 60 amps, you must use a feeder rated no less than a 60 amp rated conductor, from the transformer, through to the main lugs of the service panel, or the lug of your main over-current device depending on the service rated panel style that you plan to use. You may use 6 awg THWN between the riser and meter base and also between the meter base and the main service rated panel NEC Table 310.16 and NEC Article 110.14.C.1.A The conduit minimum size for 6 awg would be ½”conduit no matter the type of conduit. NEC Appendix C

If your service panel main over-current device size is 100 amps in a residential setting, you must use a feeder rated no less than a 100 amp rated conductor, from the transformer, through to the main lugs of the service panel, or the lug of your main over-current device depending on the service rated panel style that you plan to use. You may use 4 awg THWN between the riser and meter base and also between the meter base and the main service rated panel NEC Table 310.15.B.6 The conduit minimum size for 4 awg would be 1”EMT conduit NEC Appendix C 1 or 1 ¼”Schedule 40 PVC conduit NEC Appendix C 10 or 1 ¼”Schedule 80 PVC conduit. NEC Appendix C 9

You must use the 60 degree column found in NEC Table 310.16 to decide the ampacity of your conductors if that conductor is smaller than 1 awg and larger than a 10 awg conductor NEC Article 240.3.D 10 awg or smaller conductors. You must use the 75 degree column found in NEC Table 310.16 to decide the ampacity of your conductors if that conductor is larger than 1 awg. This is true regardless of the temperature rating of the insulation of that conductor. NEC Article 110.14.C

The conduit size must be sized meeting the requirements of NEC Appendix C using the conduit type you plan to use compared to the conductor size and type of insulation on those conductors.

Meterbase/Supplier/Requirements

Some Utility companies will furnish that meter base for your temporary. Some Utility companies require you to furnish your meter base. You really should call your local Inspector and your local Utility company to confirm what rules apply in your area concerning that meter base. Also check with you Utility company and your local Inspector concerning any special local rules applying to temporary services. Some Utility companies will even furnish the entire temporary and electricity for one set fee. This is where you really should make those two contacts both the AHJ [local Electrical Inspector] and your serving Utility Company for specialized local rules.

An example of an overhead meter base showing line [power into meter base] and load [power out of meter base to your panel] may be viewed by clicking on the picture icon to the left.

Straps/Where Required

You must support the pipe with straps. The NEC states that you must install a strap near each end of the conduit. Check the support requirements of the style and type of conduits you are using. Keep in mind that if the conduit is installed below the height of the meterbase chances are that conduit will be considered as subject to physical damage requiring heavy wall conduit approved for use where subject to physical damage. Please confirm that the conduits being installed below approximately 6' are approved where subject to physical damage.

Feeder/Style /Type/Size

If you are using this temporary on a residential application, you may size your feeders by NEC Table 310.15.B.6 allowing a reduction in size from that required for commercial use. If you are using this temporary on a non-residential unit you must size your feeder by NEC Table 310.16

Special Note: Keep in mind that the chart in NEC Article 310.16 must be adapted to meet the requirements of NEC Article 110.14.C. If the conductor required is smaller than a 1 AWG. but larger than a 10 awg conductor then the temperature rating of the conductor as per the ampacity in NEC Table 310.16 must be limited to 60 degree centigrade [such as the column for TW conductors] regardless if the conductor is rated 75 or 90 degree such as THHN Conductors. If the conductors are used as a feeder for a residential setting then you may disregard the temperature limitations and use the NEC Table 310.15.B.6 exclusively with no temperature rating in your concerns. This use of NEC Table 310.15.B.6 may be controversial when used on a residential setting yet on a temporary. Please contact you local AHJ [Electrical Inspector] to confirm that you are allowed to use this table in your local area.

In this application you must use a conductor approved for a wet location, and approved as a service conductor [with a "W" in it's identification and sunlight resistant] NEC Article 310.8.D Please leave approximately 3' sticking out beyond the weatherhead allowing enough conductor length that the Power Company may have enough to work with during their connection to your service entrance conductors. Please identify the neutral with either a white or gray identifying means. NEC Article 200.6.A and B

The following feeders are accepted practice to use in this application to serve as a service entrance conductor serving an overhead temporary, but this list does not name all conductors approved for this application.

Sunlight Resistant Copper Conductors

15 amp rated contained within a ½”conduit NEC Appendix C = 14 awg THWN / OR / THW / OR / XHHW NEC Article 240.3.D

30 amp rated contained within a ½”conduit NEC Appendix C = 10 awg. THWN / OR / THW / OR / XHHW NEC Article 240.3.D

60 amp rated contained within a ¾”conduit NEC Appendix C = 6 awg. THWN / OR / THW / OR XHHW NEC Table 310/16

100 amp rated contained within a 1”conduit NEC Appendix C = 4 awg. THWN / OR / THW / OR XHHW {residential} NEC Table 310.15.B.6

200 amp rated contained within a 1 ½”conduit NEC Appendix C = 2/0 awg. THWN / OR / THW / OR XHHW {residential} NEC Table 310.15.B.6

Aluminum Feeders

15 amp rated contained within a ½”conduit NEC Appendix C = 12 awg THWN / OR / THW / OR / XHHW NEC Article 240.3.D

30 amp rated contained within a ½”EMT or schedule 40 PVC conduit NEC Appendix C1 and NEC Appendix C10 or contained within a ¾”schedule 80 PVC conduit NEC Appendix C9 = 8 awg. THWN / OR / THW / OR / XHHW NEC Table 310.16

60 amp rated contained within a 1”conduit NEC Appendix C = 4 awg. THWN / OR / THW / OR XHHW NEC Table 310/16 and NEC Article 240.4.B

100 amp rated contained within a 1”EMT or schedule 40 PVC conduit NEC Appendix C1 and C10 or contained within a 1 ¼”schedule 80 PVC NEC Appendix C9 = 2 awg. THWN / OR / THW / OR XHHW {residential} NEC Table 310.15.B.6

200 amp rated contained within a 2”conduit NEC Appendix C = 4/0 awg. THWN / OR / THW / OR XHHW {residential} NEC Table 310.15.B.6

Special Note: If you are using aluminum wiring you must use anti-oxidation inhibitor [Nolox] at each connection of that aluminum conductor.

Riser Pipe/Type/Style

Accepted practice will lead you to Sch 40 PVC due to a cost factor. You may use Sch 80 PVC, EMT, Rigid conduit or several other types of conduit in this occasion also.

Special Note: If you are using the riser as support for the service drop coming from the power pole then you must use a minimum size rigid conduit of 2”

Transformer

Your Utility Company will flag the area where they plan to set your transformer and provide the maximum distance allowed for your overhead temporary from the Utility pole and you overhead temporary Your Utility Company will furnish your transformer for you.

Grounding Requirements

You must drive a 1/2" x 8' minimum size made grounding electrode [Ground rod] at your temporary. NEC Article 250.52.A.5.B

You must then run the grounding electrode conductor up the pole to the service panel. NEC Article 250.64

You must not use an aluminum grounding electrode in direct contact with the earth. NEC Article 250.64

Absolute minimum grounding electrode conductor size is a # 8 copper for 100 amp or less and # 6 copper for more than 100 amp. NEC Article 250.66

Grounding service conductor sizes between a ground rod and a service panel are as follows;

30 amp feeder = # 8 copper grounding electrode conductor NEC Article 250.66

60 amp feeder = # 8 copper grounding electrode conductor NEC Article 250.66

100 amp feeder = # 8 copper grounding electrode conductor NEC Article 250.66

Special note: If installing a grounding electrode conductor to a made electrode the maximum grounding electrode conductor size required is a 6 awg copper conductor NEC Article 250.66.A

200 amp feeder = # 6 copper grounding electrode conductor to a made electrode. [ground rod] NEC Article 250.66.A

General Info on Temporary Approved Length of Time to be Used

The maximum allowable time for any type of temporary wiring are as follows; 90 DAYS on non construction type projects. NEC Article 527.3.A and B

LIFE OF CONSTRUCTION PROJECT where on a construction site as long as construction process is an active construction project. NEC Article 527.3.A and B

Special Note: The temporary wiring style running from the temporary on the load side of the overcurrent device is rather forgiving on a temporary wiring condition. You must show that the temporary wiring is under a controlled supervision. [ NOT AS SERVICE EQUIPMENT BUT ON THE LOAD SIDE OF AN OVERCURRENT DEVICE] NEC Article 527.3.A and B

Special Note: Pole braces are required on an overhead temporary mounted 3/4 of the way to top of the pole and made in a “V”pattern with the wide part of that “V”pattern pointing toward the serving utility pole so that those braces are pushing into the earth instead of pulling out of the earth. These braces must be installed unless the supporting temporary pole is proven to be buried 5' or more below undisturbed dirt or to a depth in the earth equal to 1/3 the total length of that supporting temporary pole as required by most AHJs [Electrical Inspectors].

One last look at an overview example of an overhead temporary may be viewed by clicking on the picture icon to the left.

This document is based on the 2002 national electrical code and is designed to give you an option, as a self - help, that should pass minimum code requirements. While extensive research has been implemented in the preparation of this self - help document, the author and / or provider of this document assumes no responsibility for errors or omissions, nor is any liability assumed from the use of the information contained within this document by the author or provider.

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