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OK cheersYes, all power and lights go. None of the individual switches flip, just the main rcd switch.
Discuss Mitre saw tripping main breaker - Help! in the Electrical Tools and Products area at ElectriciansForums.net
OK cheersYes, all power and lights go. None of the individual switches flip, just the main rcd switch.
That's the right question to ask - if it is an illegal Neutral - Earth short in the house it should cause the trip when any significant current appliance is used - certainly on the same ciruit - though the saw start-up current surge will be high and could trip the Doepke 30 mA type B trip whereas a simple load (like a kettle) may not. The saw is double insulated - so if it is the RCCB that is tripping - which it is - it almost has to be an improper N-E short in the wiring - OR in an appliance that has been added in the last few weeks. It can't be tripping on surge current (a 63 A MCB) so it must be the imbalance that is causing the tripping. I suggest unplugging all appliances (washing m/c, fridge, cooker, etc) and seeing if the saw still trips the power. If it does - then get a qualified electrician in to sort the problem. Electrical safety issues like this need to be sorted by a qualified and experienced professional.No other similarly rated appliance does this like the kettle for example.
I suggest unplugging all appliances (washing m/c, fridge, cooker, etc) and seeing if the saw still trips the power.
Another relatively common cause of Neutral - Earth short are immersion heater failures. It may not be a full short but just a low impedance so it needs the high surge current to generate the current required to trip the RCCB. Whatever the problem - a failing RCCB tripping too easily, or a N-E s/c problem - you really need to get a good local electrician in to do the tests and measurements and, as you recently bought the house, ideally a full condition report. Don't stint on electrical safety.Did this previously (forgot to mention!), still tripped.
You almost certainly have a Neutral-Earth short on the ground floor ring circuit. If you don't know how to find that, get a qualified electrician in.OK, I'm pretty sure I've narrowed it down to the wiring itself on my ground floor sockets circuit.
Plugged the saw in in the garage, switched all other circuits off apart from the garage and it worked fine. One by one switched remaining circuits on and it trips on the ground floor sockets.
Unplugged absolutely everything from downstairs sockets and tried again. Tripped.
The only uncertainties I have are the boiler and an outdoor security light (seemingly non-working). They are hard wired, inside a downstairs cupboard so I couldn't physically unplug them, but just switch them off at the wall). I don't know if this is relevant or not?
Having hopefully eliminated all of the appliances, I'm assuming there is no further testing I can do myself?
Thanks again for all the help so far!
I hope the boiler and the outside security light are on fused outlets. They are both possible candidates for the short. And, no, switching them off will make no difference as the Neutral will not be switched.You almost certainly have a Neutral-Earth short on the ground floor ring circuit. If you don't know how to find that, get a qualified electrician in.
Most switched spurs are double pole.I hope the boiler and the outside security light are on fused outlets. They are both possible candidates for the short. And, no, switching them off will make no difference as the Neutral will not be switched.
I hope the boiler and the outside security light are on fused outlets. They are both possible candidates for the short. And, no, switching them off will make no difference as the Neutral will not be switched.You almost certainly have a Neutral-Earth short on the ground floor ring circuit. If you don't know how to find that, get a qualified electrician in.
True, most are, if they are wired correctly - assuming they are both proper fused spur outlets - the boiler probably is - and not just a light switch for the security light put in by some previous DIY person. I have seen that before for outside lights. Anyway, I appreciate the correction and reminder. It is most likely to be a N-E short elsewhere on the circuit then. It doesn't change the fact that he needs to get expert practical help on site. It is passed the guessing stage.Most switched spurs are double pole.
I hope the boiler and the outside security light are on fused outlets. They are both possible candidates for the short. And, no, switching them off will make no difference as the Neutral will not be switched.
Funnily enough I have the same saw as Joe and as do many others we all have the same or similar problem. Mine is a lumberjack make but identical and I mean identical in every respect except the colour. I have a 32 amp consumer unit in the workshop it has a 6amp mcb a 16amp mcb and two 32 amp mcbs only the 6amp and 16amp are being used. The 16amp is a complete ring around the workshop when I put my saw in and try to use it , it trips the mcb only the mcb 16 amp but if I plug it into my 25meter extension it works no problem and never trips the mcb ....why and how do I fix it. The saw is only a week old out of the box?Hi all
I've just signed up to the forum as I'm at a loss with what the problem is - I've asked the (sort of) electrical guy at work and he is also out of ideas.
I myself have next to no electrical knowledge, so please bare with me..
My SIP 12" Mitre saw is being problematic. 2000 w, 13amp fuse in plug.
Manual here: http://www.sipindustrial.com/manuals/01504.pdf
I've recently moved into a new home where, the first time I used the saw there were no problems at all. A week later I take the saw out and pull the trigger. The blade spins for an instant, stops immediately and the main breaker is tripped.
I then repeatedly try flipping it back on and testing it out in different sockets (upstairs, downstairs, oven socket etc.), different/no extension leads, checking the fuse, all ending up with the same result - initial spin up then trip.
I take the saw to work (carpentry workshop) - works absolutely fine. Wiggle the cable about while running it to see if the problem is there, continues to run perfectly.
I take the saw to another house just round the corner, with presumable similar wiring - absolutely fine there as well.
So I suppose:
What's wrong/different with my house that's causing the saw to trip the main breaker?
Is the saw itself problematic, but other properties seem to be able to just deal with it?
Why would it work properly on initial use but fail to work a week later?
Thank you very very much in advance!
Joe
View attachment 37244 View attachment 37245
this looks likea classic case of start up current tripping a type B MCB. the solution is usually to fit a type C, either 16A or even 20A, providing that the circuit parameters comply with a type C. also, ant replacement must be the same make as the CU assembly. (can't fit a MK in a WulexCU.).Funnily enough I have the same saw as Joe and as do many others we all have the same or similar problem. Mine is a lumberjack make but identical and I mean identical in every respect except the colour. I have a 32 amp consumer unit in the workshop it has a 6amp mcb a 16amp mcb and two 32 amp mcbs only the 6amp and 16amp are being used. The 16amp is a complete ring around the workshop when I put my saw in and try to use it , it trips the mcb only the mcb 16 amp but if I plug it into my 25meter extension it works no problem and never trips the mcb ....why and how do I fix it. The saw is only a week old out of the box?
The 16amp is a complete ring around the workshop when I put my saw in and try to use it , it trips the mcb only the mcb 16 amp but if I plug it into my 25meter extension it works no problem and never trips the mcb ....why and how do I fix it.
Hi Dave,That's a very weird arrangement, it's not normal to have a ring circuit fed by a 16A MCB.
Do you have the installation certificate from when it was installed? This will give us vital information as to whether or not the MCB could be safely replaced with one more resistant to this tripping problem. Specifically we need to know the earth fault loop impedance (Zs on the certificate) to be able to advise.
The "why" part comes down to the resistance of the extension lead limiting the motor's start-up current to a level that is below the MCB trip point.if I plug it into my 25meter extension it works no problem and never trips the mcb ....why and how do I fix it.
Hi pc1966Having a 16A MCB on the ring might have been an attempt for selectivity with a 32A or 40A MCB in the house CU.
More info on your system (e.g. what feeds the garage CU in the house) and ideally a test result on the garage CU to know what impedance there is would be useful.
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