Curious Power Issue while using Chain Saw with Extension Cable!

danrv

Try the Ryobi on a 32a circuit. That’s what I’m using for my Qualcast. 

sujsuj

grumbler said:

This MCB (yes, MCB, not RCD) is just 16A.

Your 2.3kW saw draws normally about 10A, more when it starts or is overloaded. Hardly a surprise that it trips the MCB occasionally and unpredictably.

Extension leads (unless they are faulty) have nothing to do with this.

Or it can be some fault with the saw.

But then how the RIOBI work well when I connect it directly to the socket instead of using extension cable..? No issues when I connect RIOBI directly to socket and use it!!

sujsuj

grumbler said:

Section62 said:

grumbler said:

This MCB (yes, MCB, not RCD) is just 16A.

Your 2.3kW saw draws normally about 10A, more when it starts or is overloaded. Hardly a surprise that it trips the MCB occasionally and unpredictably.

Extension leads (unless they are faulty) have nothing to do with this.

Setting the discussion about the theory aside then, can you explain why the same MCB doesn't trip when the same chainsaw is plugged into the wall socket with the extension lead(s) removed from the equation?

As I said, "occasionally and unpredictably". Most likely, without the extensions lead the tests were short and without serious load.

Not really, I managed to cut a wood halfway when connected directly to the socket. But chainsaw will not even start when I used it with extension cable.

sujsuj

Section62 said:

sujsuj said:

grumbler said:

Jonboy_1984 said:

They create additional resistance (and heat) when coiled due to the magnetic fields.

I think, magnetic field is a myth as cable has two cores with opposite currents.

And, again, heat (poor dissipation in this case) on its own cannot cause MCB tripping

RCD tripped

sujsuj said:

tripped switch highlighted

That isn't an RCD you've highlighted.  It is an MCB.

Move your wood pile closer to the power source... will be easier, safer and cheaper.

But I am cutting a tree branch!

Eldi_Dos

sujsuj said:

Section62 said:

sujsuj said:

grumbler said:

Jonboy_1984 said:

They create additional resistance (and heat) when coiled due to the magnetic fields.

I think, magnetic field is a myth as cable has two cores with opposite currents.

And, again, heat (poor dissipation in this case) on its own cannot cause MCB tripping

RCD tripped

sujsuj said:

tripped switch highlighted

That isn't an RCD you've highlighted.  It is an MCB.

Move your wood pile closer to the power source... will be easier, safer and cheaper.

But I am cutting a tree branch!

Pruning saw would be cheaper and more efficient with the benefit you could use in damp conditions.

QrizB

Section62 said:

grumbler said:

This MCB (yes, MCB, not RCD) is just 16A.

Your 2.3kW saw draws normally about 10A, more when it starts or is overloaded. Hardly a surprise that it trips the MCB occasionally and unpredictably.

Extension leads (unless they are faulty) have nothing to do with this.

Setting the discussion about the theory aside then, can you explain why the same MCB doesn't trip when the same chainsaw is plugged into the wall socket with the extension lead(s) removed from the equation?

Maybe because he unplugs his fan heater and plugs it in there instead?

(Said in jest but let's not forget that the chainsaw might not be the only thing on the circuit.)

Jonboy_1984

Are there any other devices on the same circuit (i.e. they also lose power when the switch goes to off). If so what are they?

Ectophile

With a long extension lead, there will be additional resistance in the circuit.  That will make it harder for the chainsaw to start up, and it may take longer to get up to speed.

The circuit breakers commonly used in houses are specified to allow brief surges of current as motorised things start up.  But if that surge is extended by a motor that's struggling to start, then a breaker may trip.

ThisIsWeird

SS, why aren't your other MCBs labelled? What is  supplied by the neighbouring 20A jobbies?
16A is low for 'sockets', unless it supplies a very limited number, say upstairs bedrooms. I mean, a couple of heaters used during winter would trip that MCB if used at the same time.
So, if the 20A MCB also supplies sockets, then try your saw and ext in there - they 'should' work ok, assuming no actual faults with them.

Have to say, I thought S62's remark re added resistance potentially leading to increased current draw was weird, but I get what he says - a high-draw device with a large initial surge, coupled with being laboured by a voltage drop, is a good theory - just enough to send the MCB over the top when the trigger is pulled. It wouldn't take much for a 16A MCB to trip - it's not actually a fault as such, just a too-low rated or too-fast an MCB. But, it's the one for that circuit, so shouldn't be interfered with other than by a pro. 
So, what do the 20A jobbies supply?

Jonboy_1984

They said on the second page its a garage socket, my guess is someone installed a pre-loaded consumer unit in the garage, and the unmarked 20A's are not connected to anything.

That is why I am wondering what else is plugged in on the same 16amp circuit.