Table saw problem

[rspsteve]

Mike its blowing a 10 amp fuse in the plug I put a 13 amp in and it tripped the whole thing.

Thanks everyone , I will call the sparky and get him to sort it ....of course it could still be a problem with the saw .

 

[Spindle]

Hi

Was there anything else running on the same circuit when you tried to use it the second time - the combined load then tripping the breaker?

Just a thought

Regards Mick

 

[Bluekingfisher]

If the machine is tripping fuses it is a clear indication something is over loading the system (sorry to state the iobvious) but for those guys simply changing or replacing a 13A fuse in the plug when it occasionally blows are asking for trouble. You might come back one morning to find a pile of ashes. That would definately ruin your day.

It would appear that your saw is on, or near the maximum tolerance for tripping the fuse, it being the weakest link. I think the RK is a mere coincidence unless it is arcing somewhere and causing an earth fault??

A 32 A ring main, same rating as a ring main in the house has to accomodate all other machines and electrical gizmos feeding from the circuit up to a max of 32A, again sorry to state the obvious. If your workshop is located some way from the house ( i assume you are feeding the shopo from the fuseboard in your house??) if so, the distance from the house has a bearing on the efficiency of the output at the workshop. A bit like pressure drop if you will. The longer the run the more likely to have the drop, particulary if you are running under gauge/rated cable. Did the spark who fitted your system know you intended to run such big machines from the installed 32A ring?

You will most probably need a dedicated 16A supply for you saw fitted with a C rated MCB on the fuse board. The "C" rating handles the start up amp draw of the motor (Most MCB's in a fuse board are generally "B" rated as they do not need to handle such a large amp draw when you switch it on. So for example if you fitted a B rated 20A fuse in the main board it would still trip. If you have a fuse board in the shop with spare ways, just fit the 16A C rated fuse (about £5 from electrical outlets ) and run a dedicated supply to the saw. The 16A plug and sockets are again about a fiver. In addition to supplying appropriate power to the saw it means you can unconnect the saw saw from the fuse board while not affecting your other outlets on the 32A ring main if you ever have to work on either .

Apologies if this has been an egg sucking exercise but don't take chances with electricity.

Good luck

David

 

[Random Orbital Bob]

Very useful in fact David. I'm a total dunce where electrics are concerned so a rudimentary explanation like that is really useful. So do I take it that my 16A P/T which I've installed a 13amp regular plug to and plug into my regular 32A ring main is OK given it never trips anything? In other words, though ideally it should have a separate 16A supply, its obviously not drawing quite that much current on startup so I'm getting away with 13A tolerances?

 

[rspsteve]

If the machine is tripping fuses it is a clear indication something is over loading the system (sorry to state the iobvious) but for those guys simply changing or replacing a 13A fuse in the plug when it occasionally blows are asking for trouble. You might come back one morning to find a pile of ashes. That would definately ruin your day.

It would appear that your saw is on, or near the maximum tolerance for tripping the fuse, it being the weakest link. I think the RK is a mere coincidence unless it is arcing somewhere and causing an earth fault??

Definatley not arcing out .

A 32 A ring main, same rating as a ring main in the house has to accomodate all other machines and electrical gizmos feeding from the circuit up to a max of 32A, again sorry to state the obvious. If your workshop is located some way from the house ( i assume you are feeding the shopo from the fuseboard in your house??) if so, the distance from the house has a bearing on the efficiency of the output at the workshop. A bit like pressure drop if you will. The longer the run the more likely to have the drop, particulary if you are running under gauge/rated cable. Did the spark who fitted your system know you intended to run such big machines from the installed 32A ring?

spark knew what i was running and used the correct rating amour cable

You will most probably need a dedicated 16A supply for you saw fitted with a C rated MCB on the fuse board. The "C" rating handles the start up amp draw of the motor (Most MCB's in a fuse board are generally "B" rated as they do not need to handle such a large amp draw when you switch it on. So for example if you fitted a B rated 20A fuse in the main board it would still trip. If you have a fuse board in the shop with spare ways, just fit the 16A C rated fuse (about £5 from electrical outlets ) and run a dedicated supply to the saw. The 16A plug and sockets are again about a fiver. In addition to supplying appropriate power to the saw it means you can unconnect the saw saw from the fuse board while not affecting your other outlets on the 32A ring main if you ever have to work on either .

My sparky is away till monday will call him then.

Apologies if this has been an egg sucking exercise but don't take chances with electricity.

thanks for the explaination

Good luck

David

 

[Bluekingfisher]

Hi Bob- I must first state I am not a qualified electrician, purely an ametuer with a little experience having suffered the same issues as rspsteve.

I would say that if you have a machine rated at 16A then you are talking about a 5HP motor? this being the case I am wondering how the 13A fused plug doesn't blow?? or indeed the machine run at all? 5HP machines would normally operate on a 3 phase system (415V)

Its simple maths to work out the amps rating for the machine. Amps = power(W) divided Volts (V) so in rspsteve case, a 2.5HP machine (1875W) the machine would draw around 8A while NOT under load. However, when you turn on the machine the required Amperage could rise to around half of that again, so perhaps 12 amps. A poor comparison would be, if you can remember trying to push start a car with a flat battery. The amount of effort to get it moving was lung busting but as the car got rolling the effort required to keep it moving was a lot less. Poor analogy but I hope you get the idea? you could also take into consideration things like flat tyres on the car or excessive luggage in the car, harder to start and keep moving, as it wold be if something was restricting the free movement of the working parts of the WW machine. Things like poorly adjusted drive belts blades that are too big or worn bearings etc. This of course doesn't take into consideration other factors like suitrability of cable/flexes which supply powe ro the machine, all of which create resistance,. Again if you can imagine trying to pour water down a pipe, much more problematic if for example trying to empty a bath down a 15mm pipe rather than a 110mm soil pipe. In electrical circumstances the resistence, ohms (friction) creates heat, which if you are lucky will trip the fuse or if not, melt the cable resulting in fire. Definately bad news.

So in an ideal situation with a 2.5HP rated motor he is right on the cusp of being within his tolerance but of course as parts and cabling, switches etc get older they, like most things become less efficient and tend to pack up or become intermitent during operation.

I suspect your motor is not 5HP (3 phasing would most likely be required) but somewhere around 2HP? (1.5Kw) in which case your 13A fused plug would probably see you OK.

As mentioned, I am not a qualified spark, just a bungler who through blood sweat and tears now has his own system fully operational. I have four machines all requiring a 16A supply. I have them all on individual feeds, i.e each with their own 16A C rated MCB in the shop fuse board and a single 2.5mm cable running through plastic conduit ducting to the socket point. If anything it is easier to do it this way rather than have a ring with several plug sockets on it. Much easier to maitain too.

Good luck with it.

David

 

[Random Orbital Bob]

Thanks David....that's helpful.

 

[rspsteve]

Thanks David

I have been i touch with a local machine repairer he is going to check it out next week when i am off .

He seems to think 13A is ok for this machine and is going to check it over , without seeing it he said it sounds like a capacitor has gone down , something that sorts out the extra surge on start up , we will see and i will report back .

Steve

 

[Bluekingfisher]

No problem Steve, I think you are taking the right course of action, let the expert look it over. It may well be a faulty capacitor and that will solve your problems. Dust and debris can also after a time work its way in there and affect the function of electrical components.

Good luck and let us know how you get on. I always like to shadow the "expert" when they are working on something, I find it a great way to pick up tips which would otherwise not be found in the user manuals etc

David.

 

[rspsteve]

Will update hopefully wednesday .

Cheers all .

Steve

 

[Benchwayze]

My Bosch SCMS started tripping the circuit breaker when I switched on. By plugging it into the socket furthest from the Consumer Unit, I solved the problem. Unfortunately, that put my saw too near the door, and it was too noisy for the neighbours. So I have since had a higher rating plug and socket fitted.

Maybe a more remote socket would get you by?

HTH

 

[rspsteve]

Well had a bit of a look this evening there is a very tight spot when rotating the blade....think the motor needs to be removed and further investigation needed.

Steve

 

[rspsteve]

Hi all

Had an engineer over to check out the table saw , he confirmed the 13 amp supply was well cappable of running the machine , the capacitors were fine so it looks like the bearings on the motor are definatley to blame the tight spot is too much on start up .

He is ordering up new bearings and hopefully they will be fitted and problem solved next wednesday, my next day off.

Steve

 

[carlb40]

Hi all

Had an engineer over to check out the table saw , he confirmed the 13 amp supply was well cappable of running the machine , the capacitors were fine so it looks like the bearings on the motor are definatley to blame the tight spot is too much on start up .

He is ordering up new bearings and hopefully they will be fitted and problem solved next wednesday, my next day off.

Steve

Cool - WIP :mrgreen:

 

[rspsteve]

I`ll ask him to do one..lol

 

[Grahamshed]

Perhaps not the best outcome but at least you know it is 'easily' fixable.

 

[popeye_sailorman]

I have also just bought the same saw, was doing the same thing !! Mind you i bought it as scrap ! But thought at worst new motor and switch. After stripping it down and blowing the dust out of every orifus ! hey presto it is working fine !! so maybe it is just a good clean it needs. It is now happily running on a 13amp plug on a 16amp ring !

 

[gwaygway]

The cost is about £ 4 from any supplier and the socket is the same try screwfix for cheap.
My new axminster saw draws a lot for startup with a big blade and needed 20 amp trip.

 

[devonwoody]

That riving knife you fitted. (Mentioned at the beginning of thread)

Is it causing the timber to bind against the fence (hence overload)?

What blade kerf is fitted and knife thickness are you using?

 

[rspsteve]

That riving knife you fitted. (Mentioned at the beginning of thread)

Is it causing the timber to bind against the fence (hence overload)?

What blade kerf is fitted and knife thickness are you using?

It is tripping on immediate start up not put a piece of timber on the saw since fitting the riving knife .

blade kerf is 2.8mm I think and the knife is just under that.

Steve