| Electronics > Repair |
| A/C unit earth leakage |
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| andyB2022:
Hi, I've just installed my new A/C Hisense QG35XV0E split unit. The unit is working fine. However, while I was looking at it operating, I touched the metal case of it and the balcony's railing and got a little shock. Nothing too scary, my RCD didn't trip. Then I got my Fluke meter and measured from the case straight to the railing and got a value of ~2mA. What can be the cause of this? I will ground the unit properly; it was initially connected for testing purposes. However, I don't think it's good for the unit to leak 2mA to ground permanently. |
| Gyro:
It sounds like general leakage current from interference suppression caps, motor winding insulation etc. HOWEVER it does imply that the unit isn't properly grounded which is very important for something that big, metal, and touchable. It could also be that your balcony rail isn't particularly well grounded if it is supported by dry brickwork or whatever (although it is probably more structurally anchored). Try the Fluke on AC volts - if there is any significant voltage (more than single digit) then it indicates that it isn't properly grounded, rather than some small difference in ground potentials. Don't leave it without investigation though. It will be a Class-I appliance which could become lethal if something fails and there is no solid case ground! (although the RCD would hopefully catch it). |
| indeterminate:
I don't think it's good for the unit to leak 2mA to ground permanently. It is normal The mains filter network in the AC unit is just doing its job and removing noise from the supply |
| perieanuo:
little shock means usually dozens volts, for correct grounding it's too much, doesn't matter if it's coming from static or functional leakage current. there are people feeling 12Vdc/Ac, but normally you should feel discharge of a lot more voltage potential in respect to earth. what i'm saying, your earth circuit doesn't respect the ohmic maximal value in your country (ie, you felt 50volts, earth must be below 4ogms for example, added with your earth connection to earth central connection, divide those 50V by resistance you should have between your AC earth terminal upto earth of power distribution box, the value is not ok for sure). lot of theory, bad earth connection for sure. with correct earth equivalent resistance (ohms, no more), you shouldn't feel a thing |
| SteveThackery:
My brand new Microsoft Surface laptop feels distinctly "live" when I touch it plugged in. It's more noticeable when sliding a finger across the case - I can feel a 50Hz "buzz" through the finger. I'm not concerned - I assume it is current flowing through the capacitors at the input of the separate PSU. I don't think the protective ground is carried through to the DC output. |
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