Electrical Leakage

[FACTOR]

Our electrician came around today for some routine maintenance: replace some extractor fans, new light fixtures, etc... . While here he checked something out on our main board with his hand held meter and told us there is an electrical leakage.  Please keep in mind electrics is not my field of expertise.

 

I sort of understand the concept of "electrical leakage" and it sounds like something I need to take care of. I gather a low level of leakage is normal, but he said we are above the normal range.

 

Our main cable is underground and he said water from watering the garden is one possible explanation for a decayed cable and that could be causing the leak.  

 

Jeez, I saw the cables when they were put in underground and they looked pretty heavy duty plastic, or whatever, coated and I can't believe that after just three years water could have compromised them. 

 

Any advice, thoughts? What to do about electrical leakage? Do I have to dig up the whole buried portion of the main cable, approx 25 metres, to find the problem?

 

Thanks.

[RichCor]

 "Electrical Leakage" is any undesired current running along an undesired path. Anything other than an electrical appliance that allows a LIVE wire current to be conveyed to NEUTRAL or GROUND is considered an electrical leak. As such, "Electrical Leakage" can run from Deadly Dangerous to just Expensive, depending on where it's occurring.

 

I'd say you need to find out more information on where the electrician believes the 'leak' is occurring -- and how dangerous the condition may be.

 

If the leak is occurring AFTER the CU/Breaker Box then it may be possible to isolate the branch circuit and temporarily disconnect it until you can get it repaired.  If the electrical leak is BEFORE the CU/Breaker Box then I'd suggest you get professional crew in to take care of it pronto.

[FACTOR]

RichCor, thanks for the reply.

 

Question: how is the location, or source, of the leakage actually determined? 

[Crossy]

3 hours ago, FACTOR said:

RichCor, thanks for the reply.

 

Question: how is the location, or source, of the leakage actually determined? 

 

Not always easy, if you can identify which circuit is leaking and split it until the leak stops (half-split fault finding) you can then try to isolate where the actual failure is.

 

Do you know exactly what he was checking? A meter for directly measuring the leakage isn't something that finds its way into the average Thai sparkie's toolbox (or for that matter the average Brit sparks van).

 

http://www.fluke.com/fluke/then/clamp-meters/fluke-360.htm?pid=56072

 

"Only" USD 700

 

Do you have an RCD/RCBO/Safe-T-Cut device? Does it trip regularly?

 

[lopburi3]

2 hours ago, Crossy said:

Do you have an RCD/RCBO/Safe-T-Cut device? Does it trip regularly?

 

Indeed I would guess that the lower setting of such unit is tripping rather than any measurement electrician made.   Then it becomes which breaker being off allows unit not to trip at lowest setting?  And then what on that breaker is leaking.  But this would not explain why he suspects feed from meter to house.  Did he perhaps check voltage at meter and again at box and find a loss?  

 

But if no adjustable RCD type device not sure how he determined this - did he measure voltage at meter and again at house?

[Crossy]

14 minutes ago, lopburi3 said:

But if no adjustable RCD type device not sure how he determined this - did he measure voltage at meter and again at house?

 

A leak to ground on the buried incomer won't cause a measurable volt drop, the source impedance is just way too low.

 

I wonder if sparky is trying to drum up some business.

[bankruatsteve]

Did your electrician offer a solution or plan to resolve the problem or did he just notify you?  I don't know how he could determine leakage in the mains by checking at the CU.

 

[thedemon]

In Thailand it seems quite common that in some houses if you touch an electrical appliance (e.g. a desktop computer case) you will get a slight zap. Not enough to hurt but enough to startle.

 

I have often wondered what exactly causes this. Is it leakage as being discussed in this topic?

[Crossy]

1 minute ago, thedemon said:

In Thailand it seems quite common that in some houses if you touch an electrical appliance (e.g. a desktop computer case) you will get a slight zap. Not enough to hurt but enough to startle.

 

I have often wondered what exactly causes this. Is it leakage as being discussed in this topic?

 

Sort of.

 

The tingle you feel is indeed leakage, usually caused by the mains inlet filter of a switching power supply. These are intended to be grounded, the leakage current is tiny, not in itself hazardous, but as you have found can startle. Without the ground the filter can float the metalwork to about 50% of the supply voltage.

 

Any Class-1 appliance (pretty well anything with metal casework) needs to be grounded to prevent this minor zaps during normal operation and (more importantly) prevent the major (lethal) zaps that may occur during a malfunction.

 

[bankruatsteve]

2 minutes ago, thedemon said:

In Thailand it seems quite common that in some houses if you touch an electrical appliance (e.g. a desktop computer case) you will get a slight zap. Not enough to hurt but enough to startle.

 

I have often wondered what exactly causes this. Is it leakage as being discussed in this topic?

Perhaps but I think the jury is still out.  The "zap" you get is from class-1 equipment that is not grounded.  "Not grounded" means only 2-hole receptacle and/or no ground rod with grounding wire running from the CU to all power outlets.

[thedemon]

Thanks very much for the replies.

 

The house I live in now doesn't have this issue. However my neighbour's house which was built a little after mine and electrical work done by the same contractor, does have the issue.

 

Anecdotally, my neighbour does seem to have more problems that I do with electrical issues e.g. small transformers burning out.

 

Could there be a relationship between these problems and the zap issue?

 

Also is there an easy way to diagnose the issue and rectify it? 

[bankruatsteve]

Very easy.  Do you have 3-prong power outlets?  Do you have a ground rod with wire running to your CU and a bunch of green wires running into the box?  If so, you have ground.

 

Otherwise, could be you don't have any class-1 stuff and not an issue for you (yet).  But, "small transformers burning out" - what's that about?

[lopburi3]

1 hour ago, Crossy said:

 

A leak to ground on the buried incomer won't cause a measurable volt drop, the source impedance is just way too low.

 

I wonder if sparky is trying to drum up some business.

Was thinking too small or too long rather than actual leakage - as that seems to be what he was talking about and am sure he did not measure leakage.

[Crossy]

8 minutes ago, lopburi3 said:

Was thinking too small or too long rather than actual leakage - as that seems to be what he was talking about and am sure he did not measure leakage.

 

Yes, something could well have been lost in translation.

[FACTOR]

Thanks for all the replies. Yes, he checked at the CU. Yes, I have a Safe-T Cut type device (you mean a main box with a bunch of switches, right?) No, it doesn't trip much, in fact, never. I do feel a tingle in both showers, coming from the metal/plastic hoses on the shower heads. But we don't we use the hot water boxes anymore because of that. Maybe the leak is due to the tingles in the showers, or rather the tingles are caused by the leak. 

 

Yeah, maybe the sparky is trying to drum up business. No way of knowing at this point. His "plan" is A. to come back after Lao New Year is finished, in a week or so. and B. it sounds like he wants to dig up the garden where the main cable is buried and start looking there. Apart from that I can't figure out much more. My wife is acting as go between/translator, of course. 

 

 

One thing I have gathered from the useful replies you all have sent me is that one of the first things that needs to be determined is if the leak is occurring before or after the CU. 

 

More tips and insights are appreciated.

 

Thanks.

[Crossy]

If you are getting tingles in the shower, are your shower units correctly grounded? THIS IS VITAL FOR THE AVOIDANCE OF DEATH!!!!

 

If you don't know, pop the lid of one of the shower units (power off please) and post a photo of the electrical connections.

 

Does your Safe-T-Cut have a "Test" button, (the sign of an RCD/RCBO), does it trip if you press it?

 

 

[lopburi3]

He says a main box with a bunch of switch (breakers) so not sure he actually has a Safe-t-cut or such.  Also not clear if any type of ground for electric or showers. 

[FACTOR]

3 hours ago, Crossy said:

If you are getting tingles in the shower, are your shower units correctly grounded? THIS IS VITAL FOR THE AVOIDANCE OF DEATH!!!!

 

If you don't know, pop the lid of one of the shower units (power off please) and post a photo of the electrical connections.

 

Does your Safe-T-Cut have a "Test" button, (the sign of an RCD/RCBO), does it trip if you press it?

 

 

Crossy -- Tomorrow I will try to get some photos of the shower unit electrical connections and a photo of my Safe-T Cut and try to post them on this thread. I have not had luck in the past posting photos on TV but I will try again tomorrow. 

 

Thanks.

[FACTOR]

3 hours ago, lopburi3 said:

He says a main box with a bunch of switch (breakers) so not sure he actually has a Safe-t-cut or such.  Also not clear if any type of ground for electric or showers. 

The electrician who installed the showers assured me they were grounded. And I see a cable leading from the shower units to the ground.

 

Tomorrow, I will take a photo of my CU and try to post it so you guys can take a look at it.

 

Thanks.

[RichCor]

As other's have noted, I'm also dubious how the electrician arrived at his Electrical Leakage finding.

 

Not saying it isn't happening, as odd power conditions can occur if your CU is wired for Earth-Ground but your Earth-Ground Rod connection has failed, or if the CU doesn't have the 'MEN' Earth-Ground Neutral bridge wired in place. Or a variety of other scenarios. But that can wait for the pictures.

 

If an Electrical Leakage was occurring prior to your CU/Breaker Box, you *might* be able to see this by powering OFF the MAIN BREAKER and see if your Power Meter is still ticking over.  If it is, even only a little bit, this would indicate something prior to the CU is causing energy usage.

 

If you truly have a functional Safe-T-Cut or RCD (Residual Current Device) that's properly wired in place then this should indicate you don't have electrical leakage OCCURRING TO GROUND after your Safe-T-Cut device (or at least none stronger that it's current trip setting).

 

So... my request for photos would be:

CU / Breaker Box (cover off)

The Outside Ground Rod

Shower Heaters (cover off)  

...and if the Water Heater Ground-Wire doesn't go back to the CU / Breaker, then photos showing the dedicated Ground Rod connection

 

 

 

When posting images, if on a PC, then look for the Choose Files link at the bottom of the editor box, find and upload the images you want to upload, then place those images in your post by setting an inset point (the flashing '|' ) where you want the image to appear and click an image from the Uploaded Images area:

 

 

[elgordo38]

On 4/11/2017 at 11:18 PM, RichCor said:

 "Electrical Leakage" is any undesired current running along an undesired path. Anything other than an electrical appliance that allows a LIVE wire current to be conveyed to NEUTRAL or GROUND is considered an electrical leak. As such, "Electrical Leakage" can run from Deadly Dangerous to just Expensive, depending on where it's occurring.

 

I'd say you need to find out more information on where the electrician believes the 'leak' is occurring -- and how dangerous the condition may be.

 

If the leak is occurring AFTER the CU/Breaker Box then it may be possible to isolate the branch circuit and temporarily disconnect it until you can get it repaired.  If the electrical leak is BEFORE the CU/Breaker Box then I'd suggest you get professional crew in to take care of it pronto.

I sympathize with your problem its second opinion time worth the money. If factual it could be dangerous then again your electrician could be lining himself up to lining his pockets with your money. Due to the gravity of the situation I would even consider a 3rd opinion might be in order. 

[RBOP]

I was getting a mild buzz almost like a vibration when running my fingers across the metal case of my notebook computer. Always happens when there is no ground wire hooked up to the outlet. When there is a gound wire, the buzz feeling goes away. Was getting some mild shocks from the metal casing from my outdoor aircon condensor. After hooking up a ground wire the shocks disappeared. I guess proper grounding is very important.

[bankruatsteve]

Some of us don't need to guess, but there you go.  Good to hear you "got it".

[xerostar]

This situation reminded me of when my wife called a plumber because the pressure pump kept switching on at regular intervals, day and night.

The house was built to my specs with all plumbing hidden under floor and in walls as is normal for Oz. 

This all happened while I was away.

The plumber diagnosed "a leak". They dug up half the bathroom and could not find the leak. So he said the only choice was to re-plumb the whole house.

My wife didn't bother to ask me and went ahead with re-plumbing the whole house with ugly blue pipes running down from the ceiling in the kitchen and bathrooms. 

If she'd asked me I would have told her the top-up valve in the swimming pool tank was probably leaking and I'm sure that was the cause.

So I would be very skeptical about Tradesmen in Thailand diagnosing  things to their advantage.

Although admittedly, with electricity it is more a safety concern than a water leak.

Oh and they replaced the dug-up section of the bathroom with non-matching tiles.

Lovely !

[thailand49]

"Your electrician"  he opens a can of worms for you and then basically leaves you hanging. The guy has some type of meter not known to the average guy but opens a can of worm and leaves you hanging. I get a second opinion Thai or not, frustration right? if the guy can't fix it or tell you who to call then in the future get rid of him.

[Muhendis]

2 minutes ago, RBOP said:

I was getting a mild buzz almost like a vibration when running my fingers across the metal case of my notebook computer. Always happens when there is no ground wire hooked up to the outlet. When there is a gound wire, the buzz feeling goes away. Was getting some mild shocks from the metal casing from my outdoor aircon condensor. After hooking up a ground wire the shocks disappeared. I guess proper grounding is very important.

Proper grounding is indeed important the mild shocks are, as Crossy has already said, due to a capacitive coupling* of the live to the case of the appliance. If the case of the appliance is earthed/grounded then this current becomes harmless and unnoticeable/nonexistent. Any tingling feeling when touching an appliance case is a sure indication of a missing earth/ground and needs to be fixed like yesterday. The electrician may have spotted something but is quite likely making a big thing of it until he can understand it better. Or he sees an opportunity to dig up your garden. Take note of Crossy's suggestion that his test equipment may not necessarily be intended for the measurements he needed to make. I note that there is no remark about safety trips cutting out which, if they are installed properly, would indicate that YOU are protected. If there is leakage prior to the consumer unit then that could show up in unexpectedly high bills.

 

* A capacitive coupling is a description of the capability of a capacitor (electronic component or close proximity of electrical conductors) to allow the alternating voltage/current of one circuit to transfer to another.

[bazza73]

On 4/12/2017 at 10:24 AM, Crossy said:

 

Sort of.

 

The tingle you feel is indeed leakage, usually caused by the mains inlet filter of a switching power supply. These are intended to be grounded, the leakage current is tiny, not in itself hazardous, but as you have found can startle. Without the ground the filter can float the metalwork to about 50% of the supply voltage.

 

Any Class-1 appliance (pretty well anything with metal casework) needs to be grounded to prevent this minor zaps during normal operation and (more importantly) prevent the major (lethal) zaps that may occur during a malfunction.

 

I've noticed with two metal kettles in the house I get zapped. Changed to plastic and the problem disappeared. Haven't seen or felt a problem anywhere else in the house, hot water units included. Could this be the leakage you speak of?

[fdch]

On 4/12/2017 at 6:36 AM, FACTOR said:

RichCor, thanks for the reply.

 

Question: how is the location, or source, of the leakage actually determined? 

i had some what of the same

mostly because of the wiring here in thailand is to thin and the fuses are far to high(20 or 30 amps) you can by using to much apliances on 1 group melt the housing of the cables

if a + conects with a - the fuse will blow

but if a plus connects with a ground cable  it is an expensive leak and  the fuse and most of the grounding switches here will not disconnect

so u use power all the time

i had this , i just took all my grounding cables of 1 by 1 untill i found the leak replaced the wire from this circuit ,

problem solved

[Crossy]

Several posts removed, let's try to stick to the forum rules people.

 

[Wirejerker]

Wow. This is fantastic
1. The wife is acting as go between/translator
2. Electrician measured with his meter leakage
3. Don't use the heaters any more cause getting tingles
Posters gone ballistic someone used the leakage word ( like the "C" word........ cancer )
I think the electrician found a high potential difference between the earth and neutral then chatted to the wife what the problem could be and as a laymen she passed on ONE of the many things it could be that made sense to her being the underground cables leaking.. OP getting tingles in the shower now that's leakage. I would be looking for a problem in the earthing. Earth rod, bad earth connection, no MEN. I would never dig up the cables until they had been checked with a megger and proved faulty



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