33-1-32

TO 33-1-32

TECHNICAL MANUAL

GENERAL INSTRUCTIONS FOR

INPUT POWER WIRING OF

ELECTRICAL/ELECTRONIC SUPPORT EQUIPMENT

This publication supersedes TO 33-1-32 dated 20 September 2007.

DISCLOSURE NOTICE - This information is furnished upon the condition that it will not be released to another nation without the specific authority of the Department of the Air Force of the United States, that it will be used for military purposes only, that individual or corporate rights originating in the information, whether patented or not, will be respected, that the recipient will report promptly to the United States, any known or suspected compromise, and that the information will be provided substantially the same degree of security afforded it by the Department of Defense of the United States. Also, regardless of any other markings on the document, it will not be downgraded or declassified without written approval of the originating United States agency.

DISTRIBUTION STATEMENT D - Distribution authorized to the Department of Defense and U.S. DoD contractors only (Administrative or Operational Use) (1 September 2004). Other requests shall be referred to 584 CBSS/GBHDE, Robins AFB, GA 31098. Questions concerning technical content shall be referred to 565 CBSS/GBLA.

WARNING - This document contains technical data whose export is restricted by the Arms Export Control Act (Title 22, U.S.C., Sec 2751, et seq.) or the Export Administration Act of 1979, as amended, Title 50, U.S.C., App. 2401 et seq. Violations of these export laws are subject to severe criminal penalties. Disseminate in accordance with provisions of DoD Directive 5230.25.

HANDLING AND DESTRUCTION NOTICE - Comply with distribution statement and destroy by any method that will prevent disclosure of contents or reconstruction of the document.

Published Under Authority of the Secretary of the Air Force

27 DECEMBER 2007

1 APPLICATION.

This technical order is applicable to all electrical/electronic support equipment that has 50, 60 and/or 400 Hz capability.

NOTE

• Support equipment which was manufactured prior to 1972 is exempt from the requirement (1C) to have the high and low input power wir-ing color-coded black and white respectively.

All grounding requirements of this technical order apply, however, the fuse holder must be wired such that its terminal closest to the panel in which it is installed will not have voltage present with the fuse removed.

• Support equipment that have inherently safe fuse holders or circuit breakers are exempt from the requirements of Paragraph 3d and Para-graph 3e. Inherently safe means the operator cannot under normal circumstances make con-tact with the high side of the power line while removing the fuse. However, upon initial re-ceipt of new support equipment or when com-pliance with this TO is questionable (such as repair of input power wiring, transformer, power supply circuitry, etc.) personnel are re-quired to make sure that the fuse holder is wired into the high side of the input power line through either ohmmeter testing or visual in-spection. Visual inspection consists of seeing a physical connection between the equipment connector plug high blade and the metal con-tacts of the fuse holder. This also applies to support equipment that has undamaged fuse protective covers which prevent connection of the power cord while the fuse holder is ex-posed. If the equipment has circuit breaker(s) installed in lieu of inherently safe fuse holder(s), they shall be checked for proper high side wiring as well. Support equipment that has no fuse(s) (external or internal) in the power supply circuit shall only be checked for proper grounding at the power connection.

a. Work required to comply with this technical order will be accomplished by the activities having maintenance responsibility for the item.

b. Inspection of equipment will be accomplished prior to any internal maintenance or calibration action to make sure the requirements of this technical order are satis-fied. Since this is an on-going inspection requirement, no markings are required to indicate compliance with this technical order. Red dots required by previous technical orders are to be disregarded.

c. Figure 1 and Figure 2 of this technical order show specific examples of the types of electrical plugs and receptacles that are in common use in the Air Force.

All input power wiring for equipment items covered by this technical order shall conform to Figure 3, Fig-ure 4, Figure 5, Figure 6, Figure 7 and Figure 8 as related to the wiring of the three conductor power cord.

The black wire shall be connected to the fuse or “Hot” side, the white wire shall be connected to the Neutral, common or “Low” side and the green wire shall be connected to Ground.

NOTE

The color code for European three conductor power cord is: The brown wire shall be connected to the fuse or “Hot” side, the light blue wire shall be connected to the Neutral, common or “Low” side and the green-yellow wire shall be connected to Ground.

2 PURPOSE.

To prevent shock hazard and equipment damage by stan-dardizing all power connections on electrical/electronic sup-port equipment. This will ground the chassis of the test equipment to earth ground and eliminate a possible differ-ence in potential between these two points. If in the design of equipment type AN, M/S, cannon or other uncommon coupling is used for the power connection, the applicable equipment technical order will take precedence as to electri-cal pin designation, but will still assure proper safe equip-ment ground and proper fuse wiring. Any changes to pin configuration will only be accomplished through a Time Compliance Technical Order.

a. When possible, replace two conductor power cords with three conductor cords using the black, white, green wiring convention. The green wire in the three conductor power cable must be connected to the panel of the support equipment to provide a good ground for the case.

b. Certain support equipment cannot be modified to re-place the two conductor power receptacle with a three conductor receptacle for various reasons: Example-- Line Filter is a part of originally installed receptacle (i.e., AN/UPM 84, etc.).

c. Ground all other support equipment in the same man-ner with the exception of those items which should not be grounded in any manner (i.e., AN/USM-430, etc.).

Consult applicable technical orders on all items for precautionary actions.

d. Equipment installed as an integral part of a test con-sole which is grounded will be exempt. However, Paragraph 1 still applies to the test console and it must be in compliance with the requirements of this TO.

Inspection/correction will be made in accordance with guidelines set forth in this technical order if test equip-ment is removed from the console for maintenance, calibration and/or adjustments. Care should be taken when installing equipment with two-wire power cords in the test console in order to prevent reversal of the two-wire plug. A check can be made by attaching the two-wire power plug to the power strip/power recep-tacles of the test console and check of voltage at the metal ring (outer terminal) of the fuse holder. The outer terminal will not have voltage present with the fuse removed.

Figure 1. Equipment Connector Plug (Male Connection)

Figure 2. Power Cord Connector Receptacle (Female Connection)

Figure 3. Power Cord Connector

Figure 4. Power Cord Connector, Plug Side View

Figure 5. Power Cable Assembly

Figure 6. Power Cord/Equipment Wiring (Special)

3 PROCEDURES.

The following information is provided for electrical/elec-tronic support equipment which has integral/permanently at-tached and detachable power cords. This includes both fused equipment and equipment protected by other interruption devices, such as circuit breakers.

Disconnect equipment input power cord from power source before replacing fuses or performing corrective maintenance on electrical/electronic equipment.

NOTE

Fuse characteristics (type and current/voltage rat-ings) will be verified with applicable technical data every time maintenance or calibration actions are performed. If the fuse is inaccessible, the fuse characteristics verification is not required. This also includes inaccessibility due to warranty seals while the unit is still within the warranty period.

Ensure fuse caps properly retain fuses when re-moved from the fuse holder.

a. Make a thorough visual inspection of the power cord wiring. For integral power cords, also inspect the point of entry into the test instrument. Look for frayed or cut cords, cracks in the insulation or other defects that could pose a potential shock hazard to the operator or could damage the equipment. Repair or replace any defective parts. All equipment will be checked with a power cord attached to ensure continuity between the power cord and the instrument. Additionally, detach-able power cords must be checked for continuity while detached from the instrument by verifying correct wir-ing between the two ends of the cord in accordance with the proper diagrams of Figure 2 and Figure 3.

After the continuity check has been performed, reat-tach the power cord to the instrument.

b. Perform an ohmmeter check of the input power cord to ensure correct grounding. There shall be a resistance of two (2) OHMS or less from the outside of the TEST SET to the GROUNDING BLADE of the POWER CORD PLUG. However, some equipment manufactur-ers isolate the power line ground from the chassis to eliminate objectionable 60 Hz hum. This isolated con-dition will be detected when continuity from the test set to the grounding blade of the power cord plug in-dicates a small resistance. Consult applicable equip-ment technical orders to identify devices used to iso-late the equipment. If diodes are installed as isolation devices, reverse meter leads to make sure that continu-ity exists in both directions.

c. If grounding requirements are not met, rewire/replace defective power cord. Repair will be accomplished us-ing Figure 7 or Figure 9 and appropriate maintenance data.

NOTE

• Paragraph 3d and/or Paragraph 3e will be ac-complished upon initial receipt of new support equipment or when compliance with this TO is questionable, such as repair of input power wiring, transformers, power supply circuitry, etc.

• TO 33-1-32 is a general guideline for wiring.

Consult the applicable equipment technical or-der for verification of proper wiring if you can-not comply with Paragraph 3d or Paragraph 3e due to warranty restrictions or fuse inaccessi-bility. Compliance with Paragraph 3d and Para-graph 3e is mandatory once a warranty expires.

If improper wiring is discovered, the activity having maintenance responsibility for the item must take the necessary steps to correct the wiring prior to using the equipment.

d. Inspect all support equipment having a single line fuse for correct wiring using the following procedures. (See Figure 7.)

Correct wiring of electrical fuse holders and asso-ciated fuse circuitry is imperative. As appropriate, fuse holders refers to any circuit interrupting de-vice. There must be complete assurance that the electrical power source connection to the fuse holder terminal is completely inaccessible to body contact. Telltale lamp type fuse holders will have trickle voltage accessible to body contact. Discon-nect the input power when changing or checking fuses.

(1) Turn ON-OFF switch to OFF; disconnect power cord from power source. If necessary, remove equipment from case. Remove fuse and turn ON- OFF switch to ON.

(2) Either by visual inspection or using an ohmmeter, inspect fuse wiring to make sure the fuse holder is wired into the high side of the line. If correct, proceed to step (3).

(3) Connect an ohmmeter between the power cord high side and the outer terminal of the fuse holder.

Ohmmeter should read greater than 100K Ohm.

(4) If during the above inspection the fuse holder is found to be wired incorrectly, reverse the two wires and repeat the steps in Paragraph 3d(3).

(5) If the wiring is not correct, do not proceed. Re-solve any wiring problems before continuing.

Once the wiring and fusing are correct, replace the fuse and turn the ON/OFF switch to OFF.

Reconnect power cord to power source.

e. Inspect all support equipment having dual or multiple line fuses for correct wiring using the following proce-dure. (See Figure 9.)

(1) Turn ON-OFF switch to the OFF position. Dis-connect power cord from power source; remove the equipment from the case, if required. Remove one of the fuses and turn the ON-OFF switch to the ON position.

(2) Either by visual inspection or using an ohmmeter, inspect fuse wiring to make sure the fuse holder is wired in the HIGH side of the line. If correct, proceed to the next step.

(3) Perform step 3d(3) and step 3d(4) for the empty fuse holder. Reinstall the fuse, then remove the other fuse and repeat step 3d(3) and step 3d(4) for this fuse holder.

(4) Replace fuse(s) and turn ON-OFF switch to OFF before reconnecting power cord to power source.

Figure 7. Fuse Holder Connections

THE END

Figure 8. Power Cord/Equipment Wiring

Figure 9. Fuse Holder Connections (Hi, Lo Fused)

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COVER