Another leccie question

[SAISAY]

How can this happen?
Everything in my workshop is working fine.
Suddenly the bandsaw starts to play up and trigger the safety switch.
I unplug it, reset the switch and everything works fine.
I plug the bandsaw back in and, before I even have time to turn the power on at the wall, the safety switch goes out again. It doesn't matter which powerpoint I use, the same thing happens.
I thought that, as long as the powerpoint is off, there is no connection to the power but STILL the switch gets triggered.
If there is a white elephant to be bought, I will be the one to buy it :(
Can a possibly damaged cord do this?
I cannot remember anything happening to the cord but, hey, anything is possible in a workshop.
Wolffie

[thatirwinfella]

either an extension cord or cable in the wall has been damaged, and is creating a path to earth. it could possibly a loose connection at a powerpoint into which dust or moisture has entered.

[Pat]

Wolfie, for your own safety, get a sparky to check the Bandsaw and your shed's electrical system.

[SAISAY]

I would if I could but I can't so I won't.
It is easier to pull teeth on a chook than to get a sparky to come out here, too many much more profitable jobs around on the farms.

"Sorry, we are too busy to travel that far, maybe in 6 months!!":(

It is only the bandsaw that is causing the problem. MIght be cheaper to buy a new one even though this one is less than 6 months old.
I have tested all the wires on the machine with the multitester for conductivity and cannot find any problems even when wriggling the wires vigorously, the magnetic switch only shows contact when on, as soon as I release it (pretending there is no power on it) there is no contact.
I wonder whether this thing condenser? could cause the problem seeing it is intermittent?
I do not know how to test it.
If I use an extension cord to another part of the house, the same thing happens, so I do not thing it is the electrical system in the house.

Wolffie

[SAISAY]

I was reading on another post about multiple RCDs.
Here is a pic of my circuitboard, do I need to have another RCD installed?
http://www.woodworkforums.ubeaut.com.au/attachment.php?attachmentid=73251
The incoming power is 40A.
When we had the circuitboard installed, we thought it better to have several circuitbreakers installed, in case something short circuited but was told one RCD was enough, as we never use that many things at the same time.
Wolffie

[Wood Borer]

What an electrician would do is to isolate the problem.

They would disconnect the motor and see if was causing the problem, then the wiring between the switch and the motor etc until they found what was causing the problem.

With the cord disconnected from the power point, ask an electrician to measure for continuity between active and neutral, active and earth and neutral and earth. There should be no continuity between any of these terminals. If there is, that will be your problem.

I am not suggesting that you perform these tests because it sounds like you are not a qualified electrician and that would not be legal.

[montiee]

They would disconnect the motor and see if was causing the problem, then the wiring between the switch and the motor etc until they found what was causing the problem.

The point is that if his description is correct the motor has absolutely nothing to do with the issue (at the stage he is at) because the switch at the wall is still off. It should be isolating the component from the power. Open circuit.

It really sounds like the switch at the wall has fried itself at a minimum and is no longer working correctly and causing a short when a cord is plugged in either because the motor is blown or the outlet itself is shorting internally when pins are inserted. An electrician would probably change over the outlet with a new one because it's obviously failing without a doubt since it's no longer isolating correctly. Don't need to do any tests if the description is correct.

That's be my guess if the fuse is being triggered even if the switch is off.

You'd then need to see whether the bandsaw itself suffered damage from the powerpoint short or was the one causing the damage. You know that if it happens again it's most likely the bandsaw once it powers on again.

Edit: Actually reading the problem again you say it happens on all switches. You didn't try to plug the bandsaw and run it from the other switches did you before coming to this conclusion. Perhaps your safety switch is on the way out though your outlets should isolate anyway. Certainly a werid problem. Hell the power points may be incorrectly wired in the first place would be my guess if it's a happening on all of them. Who knows. Best to get a pro in for something like this.

[scanfor]

Wolffie, your RCD is doing exactly what it should be doing. There is a fault in the appliance. Whether the GPO is switched on or off, the very act of plugging in the cord is tripping the RCD and so it should be checked out.

Try plugging another known appliance into the same GPO and I'll bet pounds to a pinch of wallby poop that it doesn't trip the RCD. Process of elimination => appliance faulty.

[nev25]

Mate you have the same problem as before

http://www.woodworkforums.com.au/showthread.php?t=71539

Two things IMO it can be

!/WIreing
If you plug a another appliance into any Power point on the circuit that keeps tripping and the RCD don't trip Its not wiring its probably the Band saw.

2/ The RCD is detecting a low resistance between the neutral and earth in the appliance
IE when you switch off the power point the switch is only in the active conductor so it still sees the fault between neutral and earth.

A sparkie has a measuring instrument Commonly called a MEGGA that measures Insulation resistance.
You problem would be found within a few minutes.
But as you said you are having trouble getting one My suggestion if possible is to take the band saw to them

[SAISAY]

What an electrician would do is to isolate the problem.

They would disconnect the motor and see if was causing the problem, then the wiring between the switch and the motor etc until they found what was causing the problem.

With the cord disconnected from the power point, ask an electrician to measure for continuity between active and neutral, active and earth and neutral and earth. There should be no continuity between any of these terminals. If there is, that will be your problem.
No continuity between these points at all

I am not suggesting that you perform these tests because it sounds like you are not a qualified electrician and that would not be legal.
That is what I meant when I said we have tested all connections and wonder whether it could be the condenser or whatever it is called in English.
I was a sparkie in a different country many years ago, in the times of porcelain fuses, before curcuit breakers and safety switches came in, hence I do know how to test for continuity, although I may not know the English terms for things.
Wolffie

[Wood Borer]

The point is that if his description is correct the motor has absolutely nothing to do with the issue (at the stage he is at) because the switch at the wall is still off. It should be isolating the component from the power. Open circuit.

It would depend if the switch in the GPO only switched the active. If there was a path between the Neutral and Earth then this could be the problem was my thinking.

Remember he has tried it in other GPO's with the same outcome.

[SAISAY]

Mate you have the same problem as before

http://www.woodworkforums.com.au/showthread.php?t=71539
Two things IMO it can be

!/WIreing
If you plug a another appliance into any Power point on the circuit that keeps tripping and the RCD don't trip Its not wiring its probably the Band saw.
Yes, it is the same problem as before but we thought it was the power wires and did not realise it only happened when the bandsaw was connected.

2/ The RCD is detecting a low resistance between the neutral and earth in the appliance
IE when you switch off the power point the switch is only in the active conductor so it still sees the fault between neutral and earth.

A sparkie has a measuring instrument Commonly called a MEGGA that measures Insulation resistance.
You problem would be found within a few minutes.
But as you said you are having trouble getting one My suggestion if possible is to take the band saw to them
Thank you Nev, in that case I feel more confident about claiming warranty, I would feel such a fool if it was my wiring.
Oh yes, what I used is called an ohmmeter but I do not have a megger. Call it early onset of partsheimers :rolleyes:
I guess, I could take the white thingy (condenser?) :D and have it tested?
'cept it is crimped onto the motor wires.
Suppose, the motor weighs less than the complete unit.
Sometimes it is a bummer living in the middle of nowhere.
Oh yes, what I used is called an ohmmeter but I do not have a megger. after that many years I STILL have to learn the English terms :B
Wolffie

[SAISAY]

Wolffie, your RCD is doing exactly what it should be doing. There is a fault in the appliance. Whether the GPO is switched on or off, the very act of plugging in the cord is tripping the RCD and so it should be checked out.

Try plugging another known appliance into the same GPO and I'll bet pounds to a pinch of wallby poop that it doesn't trip the RCD. Process of elimination => appliance faulty.
Exactly the conclusion we came to but I just wanted to be sure..
Any other appliance in the powerpoint does NOT trigger the RCD but the bandsaw plugged into another powerpoint DOES.
It was a process of elimination that led me to the white thing whatever it is called in English.
Wolffie

[scanfor]

white thingy = capacitor

25 microFarad => probably for motor starting, not power-factor correction.

If it has failed, then usually the motor will not start, but just hum until you turn the motor shaft by hand and then it will spool-up.

It could be "leaky" though and causing some problems with the RCD. If an electrician took it out of the circuit to prove that it stopped the bandsaw tripping the RCD, then he'd have to be very careful that it was not still holding a charge - Bzzzt/Flash/Ash.

[SAISAY]

white thingy = capacitor

25 microFarad => probably for motor starting, not power-factor correction.

If it has failed, then usually the motor will not start, but just hum until you turn the motor shaft by hand and then it will spool-up.

It could be "leaky" though and causing some problems with the RCD. If an electrician took it out of the circuit to prove that it stopped the bandsaw tripping the RCD, then he'd have to be very careful that it was not still holding a charge - Bzzzt/Flash/Ash.
Thank you, warranty call tomorrow:)

:think2: Would it be an idea, if and when I can get a sparky to attend:fingerscrossed:,to have separate RCDs for House, Shed and Workshops?
Wolffie

[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 :D
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 :D
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/electricalsafety/publications/guide/resclicence/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/electricalsafety/publications/guide/resclicence/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.

:rantoff:

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.

:rantoff:

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 :2tsup:

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 :oo:
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

[Vernonv]

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

Yes you are quite correct if we were talking about the appliance on/off switch, but we were referring to the switching in power points (GPO's), which are normally single pole switches. We were also looking at why when a GPO was turned off that the RCD could still trip. Now if the GPO had a double pole switch and the GPO/switch was not faulty, then there is no way a faulty appliance can trip the RCD with the switch off (assuming the wiring to the GPO is correct).

[SAISAY]

These units have magnetic switches and cannot be started accidentally when the GPO is switched on.
We just remembered last night that about a month before we started having problems, we got hit by lightning twice in 10 minutes.
It triggered the RDC and blew the telly, fax and phones. Telly recoved after a couple of days but phones never did. Workshop was not connected at that time.
Maybe that is where our problems started?
Wolffie