HEEELLPP!! Bandsaw tripping breaker

[craigs]

This just in...

While tinkering with blade guides and fence alignment, i been doing the age old thing of "ill just test it again"....like something magical would happen and it would all start being nice. However! now when you press start, it still trips the breaker, BUT the blade moves an inch or so.

 

[RogerS]

Fit a Type C breaker. Problem sorted.

 

[craigs]

Fit a Type C breaker. Problem sorted.

that's my thinking also

 

[AJB Temple]

We all do that

Its not a breaker though. It's an RCBO. Still just a drop in, but whereas a breaker might be £5 an RCBO may be £40. Fitting is much the same. I would pop in a type C too.

 

[Spectric]

Hi

One other thought, have you something else that you could plug into that socket just to rule out the fixed wiring?

 

[craigs]

Oddly enough, when i read the specs and it said "no plug" i went and bought a spare, to which i just wired up to an outdoor security light that works like a charm.

 

[sunnybob]

Have you actually checked the wiring in the 16 amp plug on the machine? I would go straight there first.

 

[craigs]

Have you actually checked the wiring in the 16 amp plug on the machine? I would go straight there first.

The plug is good and when the blade briefly turns (an inch maybe) it goes in the right direction

 

[Trevanion]

You never have these problems with steam or water-wheel power.

 

[craigs]

You never have these problems with steam or water-wheel power.

im pretty sure im not going to get much power from flushing the lav or boiling the kettle

 

[Trevanion]

im pretty sure im not going to get much power from flushing the lav or boiling the kettle

I sell here, Sir, what all the world desires to have, POWER. Detailed plans available for purchase.

 

[TJC]

I would strongly suspect earth leakage rather than overload also.

I think there's an issue in the earthing of the machine - your 16a plug light proves the installation is correct.

 

[sometimewoodworker]

I like the video,

The type C is designed to handle the inrush current of an inductive load such as a motor, with no blade and no tension I would not expect this to trip without the motor trying to turn but your video shows instant triping. The issue with RCBO's is that you do not know if it is tripping on current due to inrush or if it is residual due to an earth leakage fault. Now as an electrician I would do something that I would never recomend to any non electrical person and that would be to temporarily bypass the RCBO and use inline protection(I have a fused link wire for this purpose) but this is not an option for yourself. The RCBO is not wired like a MCB and perhaps you may have a wiring issue, the neutral to the load does not come of a common bar, it comes from the RCBO itself with a wire from the RCBO going to the common bar. There is also a small wire that connects to the protective earth point. If you were to think of changing it then the electrician could check this out and being hands on rectify.

Sorry, though you are an electrician you seem to have missed the training that shows exactly if it’s an overload trip or earth leak trip

the flag in the window under the letters RCBO will change colour if it’s an earth leak fault, but will not if it’s an overload.

the speed of the trip suggests that an earth fault is more likely but the flag colour when tripped while not an absolute will give a better idea which it is.

This is something that anyone can safely check. The flag gets reset when you turn on the RCBO so you need to look after it trips.

 

[craigs]

Sorry, though you are an electrician you seem to have missed the training that shows exactly if it’s an overload trip or earth leak trip

the flag in the window under the letters RCBO will change colour if it’s an earth leak fault, but will not if it’s an overload.

the speed of the trip suggests that an earth fault is more likely but the flag colour when tripped while not an absolute will give a better idea which it is.

This is something that anyone can safely check. The flag gets reset when you turn on the RCBO so you need to look after it trips.

So turn it on and the flag is red, after it trips the flag is black. Same as pressing the test button.

I do remember the electrician doing earth checks when he installed the circuit which were all fine, it was only turned on yesterday for the first time.

 

[craigs]

I would strongly suspect earth leakage rather than overload also.

I think there's an issue in the earthing of the machine - your 16a plug light proves the installation is correct.

is there a simple way to test the machine earthing? not that im impatient , but i would like to get this resolved today if at all possible.

 

[MikeJhn]

As far as I know there is no such thing as a C curve RCBO, all those talking about changing for a C type are referring to an MCB which is an overload protection device only, an RCBO protects against differential current and overload protection, its Earth potential trip is supplementarity to its main function, modern RCBO's do not have the white earth connection, for the different types of RCBO's see below. Your machine may need PAT testing.

 

[Jackbequick]

Is it not the type C MCB that is more suited to motor start ups?
The sparky could have fitted a type B for a more prolonged use
if you mentioned using an extractor as well.

The spark that worked on the folks place fitted a type B for the welder.

Did you try starting the saw without a blade installed?
Or even checking the belt for tightness, slackening it a bit might help if its very tight.

Much Information....
Correct...motor start fuses (HRC type "M" ) are suited to the overload current (in Europe usually about 6 times run current). A separate circuit using motor fuses and maybe a polarised outlet so only your machine can plug into it....or have it permanently connected...A problem arises however with Circuit Breakers (and by the way C/b's and RCD's can become faulty)

You may have other devices on line reducing your 'available current before tripping'. Your installaton may not have any tpe of breaker curve suited to motor starting. You need a "C" or a "D" curve and if I had to choose one 'blind' I'd go for the "D"

Quite commonly a "C" curve breaker (about 6-7 times run current) is installed with motors....however it may not be adequate. You may need a 'D' Curve breaker (12-14 times run current) The RCD section may be not 'combo' but in line as a separate unit. A professional set up might be breaaker (with or without isolator) seriesed to overload and a contactor (3 units).

Just to explain a little....You need same high starting current awareness for circuit breakers as for fuses. Breakers (interruptors) operate more quickly and accurately than fuses...There's quite a lot of inertia being built up in a bandsaw for example and motor slip will be high, current being way above full load running.....starting current isn't reduced immediately as in a motor which is off load until up to speed.

Were the saw permanently connected an RCD would be perhaps less needed. On the other hand one can still get electroluxed through contact with live aspects of the machine. With polarisation the risk is that someone will use a polarised plug for other tools or lights...and an RCD is essential.

(Only a fool unless a sparkie who knows his onions and only does if for testing ...bypasses the RCD safety. An incident then or later would not be excused by 'just experimenting' Do the job properly.)

Testing

Firstly see the result of operating the RCD/Combo 'test switch.
Sometimes it will drop out then not reset immediately. That can be faulty rcd or faulty or overload at an outlet...maybe your saw.

One way is to ensure all outlets are known, turned off and 'do NOT use' labels attached...or disconnect them. Temporarily substitute a non-rcd breaker (5-8 minutes work whoa to go) of same current and start the machine on that.

If it drops on a "C" try a "D" or conversely...if it holds on a 'D' see what happens with several starts from "0" rpm with a "C". A tong tester might give enough reading as the needle jumps to tell the 'rough' starting current anyway...without going to that trouble. It it hits 10 amperes...a 'C' curve breaker isn't going to fix that. A 'D' curve may well do so.

RCD's, Presumably the RCD is properly connected...is your motor start capacitive?...leakage on charge can drop the rcd...that was common place on earlier TV's when the power supply was 'typical' I raised the matter with EMI and others, and the TV circuitry was altered, when I was rewiring places getting rid of the old "Standard A" earth leakage breakers . Of course the motor subject here could be faulty but your electrician can determine that.

Other stuff:
Your manual testing for mechanical freedom seems quite sensible and ok. As far as I can see unless you meant your mains fuse as you have no 100A obvious sub-circuit 100A fuse. LOndon to a brick the supply authority will have required mains fusing.... normally before the meters.

You have a 100A main switch. I don't know if you have 2 phases or whether both active and neutral are being switched or only one side used...Whichever it is 100mA rcds as MAINS protection as opposed to or as well-as main switches are commonly used to protect a property against (perhaps) electrically created fire which is not causing the sub circuit rcds to drop out.

 

[Jackbequick]

Much Information....
Correct...motor start fuses (HRC type "M" ) are suited to the overload current (in Europe usually about 6 times run current). A separate circuit using motor fuses and maybe a polarised outlet so only your machine can plug into it....or have it permanently connected...A problem arises however with Circuit Breakers (and by the way C/b's and RCD's can become faulty)

You may have other devices on line reducing your 'available current before tripping'. Your installaton may not have any tpe of breaker curve suited to motor starting. You need a "C" or a "D" curve and if I had to choose one 'blind' I'd go for the "D"

Quite commonly a "C" curve breaker (about 6-7 times run current) is installed with motors....however it may not be adequate. You may need a 'D' Curve breaker (12-14 times run current) The RCD section may be not 'combo' but in line as a separate unit. A professional set up might be breaaker (with or without isolator) seriesed to overload and a contactor (3 units).

Just to explain a little....You need same high starting current awareness for circuit breakers as for fuses. Breakers (interruptors) operate more quickly and accurately than fuses...There's quite a lot of inertia being built up in a bandsaw for example and motor slip will be high, current being way above full load running.....starting current isn't reduced immediately as in a motor which is off load until up to speed.

Were the saw permanently connected an RCD would be perhaps less needed. On the other hand one can still get electroluxed through contact with live aspects of the machine. With polarisation the risk is that someone will use a polarised plug for other tools or lights...and an RCD is essential.

(Only a fool unless a sparkie who knows his onions and only does if for testing ...bypasses the RCD safety. An incident then or later would not be excused by 'just experimenting' Do the job properly.)

Testing

Firstly see the result of operating the RCD/Combo 'test switch.
Sometimes it will drop out then not reset immediately. That can be faulty rcd or faulty or overload at an outlet...maybe your saw.

One way is to ensure all outlets are known, turned off and 'do NOT use' labels attached...or disconnect them. Temporarily substitute a non-rcd breaker (5-8 minutes work whoa to go) of same current and start the machine on that.

If it drops on a "C" try a "D" or conversely...if it holds on a 'D' see what happens with several starts from "0" rpm with a "C". A tong tester might give enough reading as the needle jumps to tell the 'rough' starting current anyway...without going to that trouble. It it hits 10 amperes...a 'C' curve breaker isn't going to fix that. A 'D' curve may well do so.

RCD's, Presumably the RCD is properly connected...is your motor start capacitive?...leakage on charge can drop the rcd...that was common place on earlier TV's when the power supply was 'typical' I raised the matter with EMI and others, and the TV circuitry was altered, when I was rewiring places getting rid of the old "Standard A" earth leakage breakers . Of course the motor subject here could be faulty but your electrician can determine that.

Other stuff:
Your manual testing for mechanical freedom seems quite sensible and ok. As far as I can see unless you meant your mains fuse as you have no 100A obvious sub-circuit 100A fuse. LOndon to a brick the supply authority will have required mains fusing.... normally before the meters.

You have a 100A main switch. I don't know if you have 2 phases or whether both active and neutral are being switched or only one side used...Whichever it is 100mA rcds as MAINS protection as opposed to or as well-as main switches are commonly used to protect a property against (perhaps) electrically created fire which is not causing the sub circuit rcds to drop out.

I forgot to add in answer to a very fair doubt by one helper 'D' curve RCD combos are available: https://www.nhp.com.au/Media/News/A...e-and-100mA-DIN-SAFE-RCBOs-are-now-available#:

 

[MikeJhn]

I forgot to add in answer to a very fair doubt by one helper 'D' curve RCD combos are available: https://www.nhp.com.au/Media/News/A...e-and-100mA-DIN-SAFE-RCBOs-are-now-available#:

At 100ma not 30ma as required for electric shock prevention.

 

[craigs]

well bugger, now i'm more confused than ever. Now i know screwfix is not an electrical wholesaler, but they do have type C RCBO's. Although the brand in the garage is Steeple, my understanding is a Wylex will fit the same.

...wait a second, wasnt it deemed to look more like an earth leak on the machine?