D04756 Rev A, Page 1 of 2 SonoSite, Inc. 21919 30 th Drive SE Bothell, WA 98021-3904 Minidock Grounding Test Problem: This problem is related to performing a “grounding impedance test” using the metal portion of the connectors found on the Minidock, when the Minidock is mounted to the Mobile Docking Station. This test comes from IEC 60601-1, Sec 18(f) and has been integrated into biomedical evaluations by some hospitals or clinics prior to use. This test involves a high current (10 A< Test Amp <25 A) and low voltage (<6VAC) where the voltage drop is measured between the test points and the impedance is calculated. The limit is .1ohm when testing between a metal part that is protectively earthed on the device and the ground pin of the detachable cord connector in the device. This test cannot be performed using the connectors of the Minidock as the test will likely damage the Minidock. Standing alone, the metal parts on the connector assembly of the Mini-Dock are not connected to protective earth and so cannot pass the grounding impedance test. When cables from peripheral devices are connected to the Mini-Dock, the metal parts of the connector assembly may be indirectly connected to protective earth if a shield within a cable is connected to protective earth and the shield connection contacts the Mini-Dock metal part. In this type of inadvertent grounding through the shield connection, impedance is invariably too high to pass the test but current will pass through the Mini-Dock connectors and adjacent circuit areas possibly causing damage to the Mini-Dock. Solution: The Mobile Docking Station can be tested to the grounding impedance test using certain other metal locations but not using the metal connectors of the Minidock. The location on the Mobile Docking System that can be tested is from the ground pin in the IEC outlet strip to the metal case of a SonoSite peripheral device where the power cord of the peripheral device is plugged into the outlet strip. Other metal parts of the Mobile Docking System should not be tested since the metal parts of the MDS do not act as an enclosure for live parts. Regarding the connections on the Minidock, such grounding would be required if in normal and single fault conditions leakage current could exceed leakage limits when measured from the ungrounded accessible metal part (IEC 60601-1, Sec 17(g)). There are exceptions to this rule limiting leakage from an accessible part. IEC 60601-1, Sec 16(a) 5 allows: “Where the occurrence of a CONDUCTIVE CONNECTION, either directly or through the body of the OPERATOR, between a part accessible without the use of a TOOL, and a PATIENT is impossible in NORMAL USE, such a part may assume, in case of a fault in its BASIC INSULATION, a voltage to earth not exceeding 25V a.c., or 60V d.c.” In normal use, or operation according to the instructions for use (IEC 60601-1, Sec 2.10.8), the patient does not contact the connector assembly of the Mini-Dock that is located in the back of the Mobile Docking Station. The voltages in the Mini-Dock are a maximum 15V dc. Thus the Mini- Dock would come under this exception and the metal parts would not need to limit leakage by being protectively earthed. Technical Bulletin Minidock Grounding Tests January 18, 2005 For Release to: All SonoSite Customers

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D04756 Rev A, Page 1 of 2

SonoSite, Inc. 21919 30th Drive SE Bothell, WA 98021-3904

Minidock Grounding Test

Problem: This problem is related to performing a grounding impedance test using the metal portion of the connectors found on the Minidock, when the Minidock is mounted to the Mobile Docking Station. This test comes from IEC 60601-1, Sec 18(f) and has been integrated into biomedical evaluations by some hospitals or clinics prior to use. This test involves a high current (10 A< Test Amp
Confidential Page 2 of 2 D04756 Rev A

The Medicines and Healthcare products Regulatory Agency (MHRA) in the UK addressed this issue and it resulted in the same analysis and conclusion (MHRA 2004/011/022/291/001-SonoSite Titan Electrical Safety Issues). See SonoSite document M01456, MHRA Finding Concerning Minidock Grounding Issue for detailed report. To contact SonoSite Technical Support Phone: (425) 951-1330 or toll free (877) 657-8118 Email: [email protected]