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Table Of Contents  CertiGuide to A+ (Core Hardware)
 9  Chapter 1010:  Safety and the Environment
      9  III  The Three Demons

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III  The Three Demons
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Dealing with EMI
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Electromagnetic Interference can be an elusive creature because it cannot be seen with the eyes. Almost every device that uses electricity is capable of producing EMI.

Electrical motors, TVs and monitors are common examples of devices that both produce EMI and are sensitive to EMI issues.

PCs usually do not cause EMI because the manufacturer must follow government guidelines regarding the generation of EMI. In the United States, the agency responsible is known as the Federal Communication Commission (FCC).

Equipment used in Canada is the province of the Canadian Radio-Television and Telecommunications Commission (CRTC).

The FCC has two classifications for electronic equipment.

They are Class A and Class B.

Class A equipment is certified for use in a business environment only. More strict standards are involved for residential use and are found as Class B standards. The FCC encourages the use of Class B devices in business environments. FCC regulations known as Part 15 contains a little bit of circular logic that reads,

"This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including the appearance that may cause undesired operation."

In English, it appears that the FCC is telling us that our equipment cannot cause radio emissions that mess with other people's equipment.

[spacer]Legally Build Your Own PC

According to Part 15 rules dated September 2000, Section 15.102, "(b) assemblers of personal computer systems employing modular CPU boards and/or power supplies are not required to test the resulting system combining the following conditions are met:

(1) Each device used in the system has been authorized as required under this part (Note: according to section 15.101 (e), some subassemblies use a personal computer system may not require an authorization);

(2) The original label and identification on each piece of equipment remains unchanged;

(3) Each responsible party's instructions to ensure compliance (including, if necessary using shielded cables or other accessories or modifications) are followed when systems is assembled; and,

(4) If the system is marketed, the resulting equipping combination has authorized under a Declaration of Conformity pursuant to Section 15.101 (c) (4) of this part and a compliance information statement, as described in Section 2.1077 (b) of this chapter, is supplied with the system. Market systems shall also comply with the labeling requirements in Section 15.19 of this part and must be supplied with the information required under Sections 15.21, 15.27 and 15.105 of this part.

(5) The a similar of a personal computer system may be required to test the system and/or make necessary modifications a system is known to cause harmful interference how or two be non-compliant with the appropriate standards the configuration in which is marketed (see Sections 2.909, 15.1, 15.27 (d) and 15.101 (e) of this Chapter).

We have included this section as direct quote from the FCC, should anyone question the legality of building a PC yourself. It used to be a big issue.

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III  The Three Demons
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Dealing with EMI
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Version 1.0 - Version Date: December 6, 2004

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