Dangerous Earth Fault? - Page 1
Forum section: electronics / general

author: tom66
author_rank: Super Contributor
timestamp: January 05, 2013, 02:05:34 pm
content: OK my dad showed me this odd phenomenon and I quickly realised it could be dangerous.There is a tingling sensation when touching the washing machine drum and an earthed faucet at same time in the kitchen. I figure it could be an earth fault perhaps?I measured 1.5mA AC and 3VAC between the drum and the faucet.I told my dad to call a licensed electrician to find the fault. At the moment it is just a tingle but am concerned it may exceed safe limits at some point in the future.Anyone heard of this before? Perhaps a leak in the washing machine? Obviously not enough to trip the RCD (says 30mA.) Electrical system (wiring, sockets, consumer unit) were checked and upgraded just a few years ago by licensed contractor.The machine is a ZANUSSI ELECTROLUX Progress 1400.

author: SeanB
author_rank: Super Contributor
timestamp: January 05, 2013, 02:18:48 pm
content: Open earth in the power lead to the washing machine, either in the cable or in the plug. What you then feel is the current that normally should flow in the earth lead that is capacitively coupled in either via the cable and motor capacitance or the internal suppression capacitors in the machine.

author: G7PSK
author_rank: Super Contributor
timestamp: January 05, 2013, 04:55:21 pm
content: My Grandmother had an AGA and a fridge near each other and if you touched both together you could get a tingle. Its something to do with different earthing points or dirty earth clamps creating a PD.

author: Stonent
author_rank: Super Contributor
timestamp: January 05, 2013, 08:19:43 pm
content: I used to get shocked all the time when removing the coax from my TV or cable modem at my old house. I measured 45V across the coax. I never could get the cable company to come out and look at it (they wanted money to troubleshoot). But they were about as useless as tits on a boar hog as most cable companies are.Didn't matter the owner which changed over many years... Telecable > TCI Cable > Comcast > Time Warner... All useless.

author: akcoder
author_rank: Contributor
timestamp: January 06, 2013, 06:54:48 am
content: Quote from: Stonent on January 05, 2013, 08:19:43 pmA good friend had this same problem, discovered the hard way. It was quite amusing when he jumped and screamed like a little girl after taking about 52v to the forearm. We stopped what ever it was we were doing and promptly fixed the grounding issue. He didn't much like getting shocked :-)-dan

author: G7PSK
author_rank: Super Contributor
timestamp: January 06, 2013, 10:04:36 am
content: I get a shock from the aerial lead of both our satellite boxes, there is 18 volts on them but this seems to be enough if you touch the core wire on the coax must be due to HF was my thought the boxes are only two leads to the mains so should be double insulated and as said before the voltage is only 18V.

author: MikeT
author_rank: Newbie
timestamp: January 06, 2013, 11:14:24 am
content: It could be you are discharging the machines suppressor/capacitor through yourself.This is a common fault if there is a faulty earth (cpc) to the machine, at switch off thecapacitor is not able to discharge itself unless someone provides an earth path.

author: PChi
author_rank: Frequent Contributor
timestamp: January 06, 2013, 12:45:23 pm
content: I think that it's worth getting out the trusty multimeter set to ohms and checking for a low resistance between the drum and the earth. It's also worth checking that the earths of the mains sockets all measure low resistance and to the incoming cable.Getting a licensed electrician is a good idea who should have the correct equipment but when it comes to safety I like to check myself as well.Some televisions used to not have a ground connection. For EMC reasons the 'chassis and coax socket' was connected to live an neutral via a couple of Class Y capacitors. So the coax had about 1/2 mains voltage on it but couldn't supply much current so was safe. I assume that with all the sockets they have these days they aren't like that any more.

author: AndyC_772
author_rank: Super Contributor
timestamp: January 06, 2013, 01:10:12 pm
content: I've had some quite nasty shocks off my AV setup. I went through every device in turn and no one item has any significant leakage between live and chassis, but the cumulative total when they're all hooked together is clearly quite high. Everything uses two pin figure-of-8 mains plugs, presumably to avoid causing hum through the speakers as a result of an earth loop.

author: SeanB
author_rank: Super Contributor
timestamp: January 06, 2013, 01:49:34 pm
content: Often you will find the coax is grounded at the service point especially if it is overhead wiring ( lightning protection so a close strike does not take out 1000 subscriber boxes that the cable company has to replace at own cost) and often this is poor or broken, so the cable floats. Add a 2 wire connection to a cable box and a psu with the input capacitor connected to the output via a 10n class Y cap and you will get a tingle and a spark. Check cable is properly connected to the earth rod by the service entrance, and add the earth if it is not there or call the cable company and moan. Outdoor TV antennas are supposed to be grounded by a minimum 4mm cable to a earth rod directly under the pole. Same for satellite TV dishes ( not that many are) as well.

author: Simon
author_rank: Unknown
timestamp: January 06, 2013, 05:40:54 pm
content: could it be that you have no earth in the house ? otherwise sounds like a faulty earth wire in the washing machine.

author: paulsev
author_rank: Contributor
timestamp: March 11, 2013, 11:57:24 am
content: The first thing you should do is call a licensed electrician, he will setup an independent earthing conductor outside by driving a copper rod into the ground to establish one. Then he will run a trailing lead from it into the house and using a volt meter try to measure resistance to earth and any possible voltage that may exist.Most importantly he will independently verify if your earthing system is good and that you don't have a burnt out neutral either, which may also cause everything in your house to become slightly live because the return from your appliances is now flowing to earth. In Australia and most other first world countries we use a "Main - Earth - Neutral" system that links the earth and neutral together and if this link is broken then every earthed appliance in the home including taps can become potentially live.