Accessibility Testing, is an integral part of the product construction review for Risk of Shock and Risk of Injury hazards. As such, it is usually done earlier in the product safety certification process, separate from the full product safety test program. Accessibility testing identifies circuits which are considered “accessible”. In most cases, it involves identifying circuits that are inadequately protected against access. The test appears to be simple to perform = checking to see if various probes will fit into openings in a product’s enclosure. However, there are many considerations in determining what probe to use, where to use it, and under what use conditions.
Risk of Shock – Accessibility: In order for the user to get “shocked”, the user must touch an electrical circuit. Ability to touch an electrical circuit is typically referred to as “accessibility”. The product safety standards specify “accessibility probes” that are used to determine what circuits are considered to be user accessible. There are different accessibility probes in different standards. Typically these same probes are also used to determine access to parts involving the potential for injury.
Accessibility Probes: The shape and size of the probes specified in the standard depend on the type of product and the age/size of the typical user (adult, children). IEC, EN, and “IEC harmonized” UL/CSA standards typically specify one set of probes while UL & CSA standards that are not harmonized to IEC standards tend to have a different set of probes. Be sure to check your product safety standards for the accessibility probes that apply to your product. Some of the more common probes include:
Purpose of the Test: To verify that there are no openings that would allow a typical user’s finger or handheld tool to access parts involving a shock or injury hazard. For example, a user’s finger contacting a rotating motor or high voltage part. Or, a screw driver inserted into an opening.
Test Preparation: Most safety standards require opening and removing all parts that can be removed or opened without tools before applying the accessibility probes. This can include using a Fingernail probe to try and pry open snapped-together parts.
Pass/Fail Criteria: Verify the exact criteria in your standard. Most standards indicate:
As you can see, we don’t simply perform the tests because they are in the standard. Each test in the standard has a set of objectives that relate to the 6 Hazards of Product Safety. Accessibility Testing is performed as part of the Risk of Shock & Risk of Injury compliance review. User access to hazardous voltages or moving parts can cause serious injury or death. It is therefore a very important test – another test that directly saves lives.
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