Common questions
Why do medical and dental rooms need 10 mA RCDs?
An ordinary safety switch trips at 30 milliamps. A patient connected to equipment, lying down, possibly sedated and with the skin’s resistance bypassed by electrodes or instruments, can be harmed by far less. So AS/NZS 3003 requires outlets in a body-protected area to be protected by RCDs that trip at 10 mA, and requires them to be located in the room, not back at the main switchboard.
Each 10 mA RCD protects a limited number of outlets, and the RCDs for one room are not shared with another, so a trip in one surgery doesn’t black out the next. The chair, and any imaging equipment in the room, sit on their own protected circuits for the same reason.
The RCDs are tested as part of the 12-monthly test, which is one reason the test matters: a safety switch that no longer trips at 10 mA is one you can’t see has failed.
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More questions
- What does a new dental surgery need electrically?
- Do I need an electrician to move a dental chair?
- How often does a medical or dental room need electrical testing?
- What is the green sign in a dental surgery or treatment room?
- Can a GP consult room be used for ECGs?
- Who certifies the electrical work in a dental or medical fit-out?
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