Another leccie question

[NCArcher]

It's not the capacitor. It has a plastic case and no connection to earth so it cannot leak current to earth. If it is 'fried' it will only prevent the motor from starting not trip the RCD.
The fault is in the Bandsaw, probably within the switch or the motor connection. The neutral and earth are continuous from the plug to the motor and are not affected by switching either the power point or the saw on. There is a low resistance path from the neutral to the earth somewhere. (either in the switch, the motor or a damged cable) the only other possibility is a problem in the plug (although not very likely)
Blow everything out with an air compressor and see what happens.

[montiee]

So just for my own curiousity can someone explain how a fault appliance causes this problem in this very specific scenario of the power outlet not being switched on?.

It has always been my understanding that the switch at the wall physically isolates the appliance from the wiring and hence fuse box. For the safety switch to trigger there has to be some current flowing which should be impossible unless the actual wiring to the switch is incorrect or the switch itself is faulty and not isolating properly.

Something is really not making sense here. Sure the appliance may trigger the safety switch but it should not if the switch itself is doing it's job and isolating the voltagae and hence current flow. There may be multiple problems imho and the wiring itself being suspect as well as a dodgy bandsaw. What am I missing?

[scanfor]

You are right NCArcher, and it sounds like the compressor trick worked for Wolffie for a while last time he had the same problem.

Montiee, the switch in the GPO (unless it is a double-pole GPO for caravans and mobile plant) will only switch the ACTIVE conductor. The Neutral and Earth stay connected at all times the plug is in the GPO. Since the RCD is monitoring all conductors, it can still see a fault between the Neutral and Earth.

[Vernonv]

So just for my own curiousity can someone explain how a fault appliance causes this problem in this very specific scenario of the power outlet not being switched on?.

The switch only isolates the active line to the appliance. The earth and neutral lines are still "connected" even with the switch turned off. If the earth and neutral lines are somehow connected within the appliance (which they should not be), it means that any current flowing through the neutral wire can leak to earth and trip the RCD.

[SAISAY]

With a stroke of good luck I found a tagger and tester who came out this morning.
He tested all connections and absolutely nothing was wrong with our wiring or extension cords..
Seems we have a temperamental RCD. No matter what he did he could not trigger it even after 2 seconds with 30 miniamps.
He thought that since we were using the bandsaw when the RCD had a tantrum, and that machine we are using at the longest time frame,it would appear like the bandsaw was the culprit when it is actually the RDC that goes on strike.
We will see what happens when we get a new one put in.
$30 very well spent
Wolffie.

[Wood Borer]

That's great news.

Does this must mean that the other GPO's you tried with the bandsaw were on the same circuit?

[NCArcher]

With a stroke of good luck I found a tagger and tester who came out this morning.
He tested all connections and absolutely nothing was wrong with our wiring or extension cords..
Seems we have a temperamental RCD. No matter what he did he could not trigger it even after 2 seconds with 30 miniamps.
He thought that since we were using the bandsaw when the RCD had a tantrum, and that machine we are using at the longest time frame,it would appear like the bandsaw was the culprit when it is actually the RDC that goes on strike.
We will see what happens when we get a new one put in.
$30 very well spent
Wolffie.

I am a little confused Wolffie,
So when the 'tagger and tester' got there the band saw was no longer causing the RCD to trip?
By tagger and tester i presume you mean someone who did a one day course at TAFE to learn how test appliances for safe operation, not an electrician.
It doesn't sound right to me (I am an electrician) the symptoms you described do not point to a faulty or temperamental RCD. You proved that the RCD will trip, if his RCD tester (I assume he was using one) could not make it trip i think he may have a problem with the tester.
When the electrician arrives to replace the RCD, have him do some further testing before you pay for a RCD that may not be required.
I don't want you to pay for a RCD and a call out and still have the bandsaw trip the circuit.

[SAISAY]

I am a little confused Wolffie,
So when the 'tagger and tester' got there the band saw was no longer causing the RCD to trip?
Correct
By tagger and tester i presume you mean someone who did a one day course at TAFE to learn how test appliances for safe operation, not an electrician.
It is a bit more involved than that here in Queensland.
Here in Queensland you have to be an electric contractor to be a self employed tester and tagger. To become that you must work for 5 years for a sparky before you are allowed to do the course and after that 3 months of paperwork and another course, then you MAY be registered as an electric contractor.
As a matter of fact, even though you are an electrician in NSW (or any other state),, you will not be allowed to be selfemployed up here without going through all the training required here and can only work under supervision up here for 5 years..
After cyclone Larry, we had many tradesmen coming up from down South but, because building codes etc. are so different up here, they were not allowed to work unsupervised without a QLD license.
I know it sounds crazy but that's the way it is.
It doesn't sound right to me (I am an electrician) the symptoms you described do not point to a faulty or temperamental RCD. You proved that the RCD will trip, if his RCD tester (I assume he was using one) could not make it trip i think he may have a problem with the tester.
I forgot what he called the tester but we were talking about the price and it was $5.000 just for the tester. He does all the contract testing for all the machine shops around here. He was very thorough and tested every connection we have in the place.
When the electrician arrives to replace the RCD, have him do some further testing before you pay for a RCD that may not be required.
I don't want you to pay for a RCD and a call out and still have the bandsaw trip the circuit.

Test and Tag Regulations Queensland:
The regulations state that, while a 'competent person' may test and tag their employer's appliances without needing an electrical licence, they do need at least a restricted electrical contractors licence if they wish to test another company's electrical equipment.
http://www.deir.qld.gov.au/electrica...icence/obtain/
I called a sparky and asked his opinion and he told me it was not the first RCD he had heard of with that problem. It is a HAGER
However, we are having the RCD changed to have different ones for the different circuits so if one triggers, we will not lose power everywhere else. He will test the RCD at the same time. Now we just have to wait for him to find the time to do it.
Wolffie

[NCArcher]

while a 'competent person' may test and tag their employer's appliances without needing an electrical licence, they do needat least a restricted electrical contractors licence if they wish to test another company's electrical equipment.
http://www.deir.qld.gov.au/electrica...icence/obtain/
I called a sparky and asked his opinion and he told me it was not the first RCD he had heard of with that problem. It is a HAGER
However, we are having the RCD changed to have different ones for the different circuits so if one triggers, we will not lose power everywhere else. He will test the RCD at the same time. Now we just have to wait for him to find the time to do it.
Wolffie

Hmm, what you stated in your reply is not entirely correct. The person who tested your bandsaw is not a qualified electrician and i hope he didn't represent himself as such. A restricted electrical contractors licence is a clasification that is awarded, after appropriate study and testing, to anyone who wants to test and tag for other than their own employer or perform disconnect/reconnect work. Plumbers often hold this license to allow them to disconnect and reconnect hot water services.
I hold unrestricted wiring licenses in NSW and Vic. I could get a Qld one, if i found it necessary, upon payment of a fee and filling out a form. I am not required to be supervised. If i want to work for myself and charge directly i have to fulfill other requirements that relate to insurance and business management.
Sorry if i'm spamming your thread but i don't like people who do a weekend course and then give out electrical advice and charge for it. A test and tag licence enables anyone to test and tag appliances and charge for the privelege not perform detailed fault finding and analysis and advise the general public on electrical matters.



Sorry about that. I hope the sparkie sorts it out for you.

[greggyboy]

Gidday mate, I'm a sparky and it sounds to me like either the bandsaw is faulty or the lead supplying it is. Just because gpo is switched off the RCD can still pick up faults. It could be an earth leakage or a high resistance Neutral. You really should get a local sparky to check it out. Good Luck. Greg

[SAISAY]

Hmm, what you stated in your reply is not entirely correct. The person who tested your bandsaw is not a qualified electrician and i hope he didn't represent himself as such. I never said he was or did. I stated what is required in Queensland to get a Restricted Electric Contractor's License
A restricted electrical contractors licence is a clasification that is awarded, after appropriate study and testing, to anyone who wants to test and tag for other than their own employer or perform disconnect/reconnect work. Plumbers often hold this license to allow them to disconnect and reconnect hot water services.
I hold unrestricted wiring licenses in NSW and Vic. I could get a Qld one, if i found it necessary, upon payment of a fee and filling out a form. I am not required to be supervised. If i want to work for myself and charge directly i have to fulfill other requirements that relate to insurance and business management.
Sorry if i'm spamming your thread but i don't like people who do a weekend course and then give out electrical advice and charge for it. Neither did I say anything about a week-end course and giving electrical advice. I said that it took him 3 month's of paperwork and 5 years of working for a licensee to even be allowed to take the course . A test and tag licence enables anyone to test and tag appliances and charge for the privelege not perform detailed fault finding and analysis and advise the general public on electrical matters. I also clearly stated that he tested all connections and could not find any faults and that, regardles off what he tried, he could not get the RDC to trigger. At no time did he offer to replace anything at all but told me clearly that he was not allowed to replace any wiring, that was the job of a sparkie.. For somebody who is trusted by all businesses here as well as the local sparkies, and has been for several years, I find your comment quite insulting on his behalf.



Sorry about that. I hope the sparkie sorts it out for you.

Furthermore,
I stated earlier, that it is easier here to pull teeth on a chook than to get a sparky to bother with testing appliances I couldn't even get one to come and do a safety test after I had a leaky roof and water damage to my overhead fan/light.
This is country Queensland where tradies do not want to travel for an hour or 2 for a measly little job, not city NSW .
Wolffie

[patty]

The switch only isolates the active line to the appliance. The earth and neutral lines are still "connected" even with the switch turned off.

No not necessarily true Many Single Phase Motors have have double Pole Switches.... which Switch Both Active and Neutral

[patty]

Sorry if i'm spamming your thread but i don't like people who do a weekend course and then give out electrical advice and charge for it. A test and tag licence enables anyone to test and tag appliances and charge for the privelege not perform detailed fault finding and analysis and advise the general public on electrical matters.

Totally agree Ncarcher I covered this on an old thread and from the responses I never made any friends!!

[elkangorito]

So far, the most important test has NOT been carried out, which is by far the most revealing test in this situation.
As I mentioned in the previous thread, an insulation test will reveal all.

I remember once being called to a supermarket (one of the "big boys") in Sydney to attend to an urgent problem. At this time, I worked for an airconditioning company & was employed as a Facilities Supervisor (mixed roles of electrical engineer & Facilities Supervisor).
The fridgy had previously replaced this 5kW three phase fan motor due to its failure (restricted electrical license) & this new motor had failed within 3 days of its' installation. The supermarket was screaming blue murder! (it was summer).

I made sure I took an insulation resistance tester with me. Also, the fridgy who had installed this new fan motor, arrived on site about 10 minutes after my arrival.
The insulation test proved these results;
1] I disconnected the motor at its' terminals & tested its' insulation resistance. One phase was down to earth (no overload protection on the load side of the contactor - a previous contractors' error).

2] I disconnected the supply & Load leads to the motor isolator & tested it. Two phases had an unacceptably low resistance between them - faulty isolator. This would not have been picked up with a multimeter.

3] I inspected the D.O.L. contactor & the Load connected wiring. Wiring showed signs of heat damage. Tested this wiring (from contactor to Line side of the isolator) - found that insulation resistance was unacceptable between two phases.

Solution;
Replace all wiring from load side of the contactor (contactor was not damaged) to the isolation switch.
Replace isolation switch.
Replace wiring from Load side of isolator just to be sure, (a short run of cable) to the motor.
Replace motor (again).
Replace contactor.

Why did this happen?
The fridgy did not carry out any fault finding as to why the first motor had failed. Nor did he know how to do this (not his fault). However, he should have flagged this as a possible electrical fault, at which point, electricians would have been called in. Luckily, the supermarket agreed to pay for this work.

What am I trying to say?
An insulation resistance test can tell you HUGE amounts about circuits. You can use multimeters until you're blue in the face but the you'll only start to get answers when an insulation test is carried out (in this case). I'm not sure if P.A.T. test devices are able to test insulation resistance. Of course, the correct "test" voltage must be selected in order to test insulation correctly. This usually requires an electrician.

[SAISAY]

I will try to explain one last time:

If this guy did not know what he was doing and did not do a thorough job when he tests electrical stuff, he would not survive here for long.

1) It is a small community and everybody knows everybody, most are related to each other in some way and they all talk to each others.

2) Big guns like Chiquita, McKays and other big bananafarms would not contract him and neither would the sugar mills.

I still think I was VERY lucky that he found the time to come out here, didn't fleece me and spent 2 hours here but only charged me for 1/2 hour

NO CALL OUT FEE.
.
But then again, that is how things are done in a small community like ours

Outsiders who come here, bringing their big city business practices do not last long but if they try to fit in, they will be given a go and everybody's door is open.

It is when we have to call out people from the big smoke that we get fleeced
If they can't blind us with science, they try to dupe us with ????????

I am NOT saying that is what is happening with the advice given here

Wolffie