'buzz' from computer and USB chargers

[smokinfun]

Hi All,

 

Live in an old apartment that didn't have much for electrical safety.  So added a saf-t-cut and grounded my box to a pipe; and everything was fine.  Go to work for a few months and upon my return; seems that something changed.  Now my Macbook gives me a 'buzz' when you touch it.  The USB cables plugged into a charger will also give you 'buzz' if you touch one.  Something changed - probably a building electrician did some work.  The question is how do the ThaiVisa knowledge base propose to repair this situation?  Okay with electricial systems - can use a multi-tester.  But what could have changed?  Where should I start to look?  The grounding connection is behind a wall; so that would be difficult to check.  On the 7th floor so running a ground to earth is impossible.  And to get the owner up to code isn't going to happen.  (and I'm not moving)  Thanks for all in sharing your experience!!

[bankruatsteve]

Grounded your box to a "pipe"?  Was it a metal pipe?  Does your box carry ground to the power points (3-pin sockets)?

 

In any case, a "buzz" from equipment is almost always due to lack of proper ground - so that is the issue.  In your case, if you cannot confirm the ground to your box, then look for any structural steel (in the ceiling perhaps) and attach another wire from that to your box ground.  Again, the ground must also go to the outlets or that will do nothing.

[lopburi3]

Use the multi tester to check voltage between live and neutral and then between live and ground.  Should be almost the same if ground working.

[Crossy]

I wonder if the building sparks managed to swap L and N.

 

Easy check with a neon screwdriver.

 

[sometimewoodworker]

2 hours ago, smokinfun said:

So added a saf-t-cut and grounded my box to a pipe

If you have a balcony try adding a bond from the railings to your pipe ground. The building steel is almost certainly an excellent Earth so if you can get to that your earth will be good.

[smokinfun]

HI there, popped the electrical outlet and sure enough my ground wire is missing.  (guess should have checked that first)  Funny thing is the 'electrician' had to do extra work to remove my ground wire instead of just leaving it in the conduit.  So now a trip to get yellow wire and run it from the box to the outlet.  Went to HomePro and asked for 3 wire cable; but seems in Thailand they only have 2 wire.  Thanks so much for all the comments; seems to be very common to lack a ground in Thailand.  Wonder how many times a grandma kicks the bucket taking the laundry out of a machine.   Safety is a personal responsibility, thanks again for the education that makes that possible.

[lopburi3]

2 minutes ago, smokinfun said:

HomePro and asked for 3 wire cable; but seems in Thailand they only have 2 wire.

They might not have but 3 wire is easily available in Thailand.  Now you know why Thailand has been ahead of the curve in buying RCCB (ground fault cut offs) - they work without ground and have been locally made here since at least 1978 (when I bought).  

[smokinfun]

20 hours ago, lopburi3 said:

They might not have but 3 wire is easily available in Thailand.  Now you know why Thailand has been ahead of the curve in buying RCCB (ground fault cut offs) - they work without ground and have been locally made here since at least 1978 (when I bought).  

Yes, but the RCCB (that is the Safe-t-cut?) works when the Amps spike; but didn't seem to help the 'buzz'.  I'm sure the 'buzz' can't be good for electronics and having you act as the ground even with a Safe-t-cut is a bit concerning.  Why doesn't everywhere else use the Thai electrical system?  2 vs. 3 wires would save a pile of money on a large scale.  Again, thanks for the information.  And the ground wire has eliminated the buzz from my USB and computer.

[bankruatsteve]

9 minutes ago, smokinfun said:

Yes, but the RCCB (that is the Safe-t-cut?) works when the Amps spike; but didn't seem to help the 'buzz'. 

That's because a "buzz", "tingle", etc. are in the microamp range.  RCD usually triggers at 30 milliamp.

[lopburi3]

That trickle buzz is not hurting the equipment (and should not hurt us if we don't physically do so in reaction) but it is not nice for us so a very good reason to make sure we have grounds - and why white appliances will always tell you to attach a ground.  Was not advocating two wire systems - changed mine to 3 wire about 30 years ago - just that there was a reason many Thai were using alternative RCCD when most of us in the 3 wire world were not.  Both ground and RCCD should be our goal IMHO.

Edited September 6, 2019 by lopburi3