Curious Power Issue while using Chain Saw with Extension Cable!

Ectophile

grumbler said:

Section62 said:

ThisIsWeird said:

sujsuj said:

Jonboy_1984 said:

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.

For More clarity, I tried chain saw directly and with extension in 2 sockets...

1.  Garage socket , remember there is a connection from Garage to the Gate control CAME as well. Game control is always plugged  & ON. When I tried direct  chainsaw in socket it worked and MCB tripped when connected with extension.
2. Conservatory Socket - There was a exercise Vibration machine also  worked from that socket, but tried after removing that machine only. When I tried direct  chainsaw in socket it worked and plug 13A fuse spoiled  when connected with extension.

I may have to try again to see if same results again. Also I have a third extension cable to be tried though it is smaller 10M one.

A 13A fuse blew when you used the socket in the conservatory? 
There is surely something more amiss here? 
'Fuses' are relatively slow- blowing, so I'm struggling to think of what condition - other than a fault with the extension cable - could make this happen.
Yes, two cables are seemingly affected, but I've just had two PV inverters come up with the exact same - and very unusual - fault within minutes of eachother. That blew my mind, nevermind anything else.

Motor starting currents can be mind blowingly high. It isn't clear the type of motor in this chainsaw, but as an example, an induction motor in locked rotor condition could draw up to 10 times the nominal running current.  If you do the voltage drop calculation using those levels of current and a long length of cable, then consider the effect of low volts on current draw for a large motor in locked rotor/startup, then it isn't difficult to figure it out.

Again, a long can make this current only lower, not higher. I stick to my guns - if the extension cable isn't faulty it can't make things worse.

What you're missing is that the motor will take longer to start up if the voltage drops because of the resistance of the cable.  So the current will be less, but there will be a high starting up current for longer.

Since that current is likely to be well over 16A, it may be enough to blow a 13A fuse or trip a 16A breaker.

chris_n

Your extension cables at 1.25mm2 are massively undersized. Assuming a start up current of 3 x tool rating you will have a voltage drop of approximately 25V. This reduction in voltage will cause the current to increase to try to satisfy the load which will pull the voltage down further etc. 
You need at least a 2.5mm2 extension, possibly more if your voltage is already on the low side. 
This problem could be indicative of other issues with size of supply cables etc as others have stated.

sujsuj

Update...

When I tested last week I think I mixed up many things..So did check things again based on feedback in the forum and have following findings.

1. When I connected RIOBI directly in the conservatory it worked and connected with extension, extension fuse failed. No surprise in this case as that socket was normal use socket. I decided not to try from that socket again.

2. When connected last week from the Garage  socket looks like there was some mix-up. Because in between I used my faulty RIOBI as well in that socket so results were inconsistant. So I tried again this week step by step... 

1. RIOBI connected directly to socked and turned ON successfully. 
2. RIOBI connected with extension-1 alone;  turned ON successfully. 
3. RIOBI connected with extension-2 alone & turned ON successfully. 
4. RIOBI connected with extension-1 then connected with extension-2 & turned ON successfully. 
   
5. (4) with on the top of tree, plug fuse failed first time, my theory is when  took to top lRIOBI level was in Off position and when I tried to run RiOBIfuse failed. Normally  it shouldn't be but it failed.
6. I got fuse replaced and tested in the ground successfully and kept level in the ON the position and moved everything to To tree branch -> All worked perfectly..

So still some inconsistancy but managed to do my job. Thanks for your support here.

sujsuj

Thanks very much.

chris_n

The inconsistency is due to being right on the edge of failure, I hadn't realised you were trying to use 2 extensions together when I commented earlier. You now have an appropriate 50V drop when trying to start up which will cause huge current increases. get yourself a proper heavy duty extension (2.5mm2) instead of the 1.25mm2 you are using before you use it again to reduce problems.

sujsuj

Last week I tried only one extension cable at a time because Conservatory was near to the trees. This week I took connection from Garage socket which is away from trees so had to connect both (one connected to other).

ThisIsWeird

sujsuj said:

Update...

I got fuse replaced and tested in the ground successfully and kept level in the ON the position and moved everything to To tree branch -> All worked perfectly.

Gulp. Are you saying you fired up the chain saw on the ground, and then climbed up the tree with the 'saw still running?

sujsuj

ThisIsWeird said:

sujsuj said:

Update...

I got fuse replaced and tested in the ground successfully and kept level in the ON the position and moved everything to To tree branch -> All worked perfectly.

Gulp. Are you saying you fired up the chain saw on the ground, and then climbed up the tree with the 'saw still running?

No, I tested it while on the ground then stopped. Gone up in ladder and tried cutting branches.

ThisIsWeird

sujsuj said:

ThisIsWeird said:

sujsuj said:

Update...

I got fuse replaced and tested in the ground successfully and kept level in the ON the position and moved everything to To tree branch -> All worked perfectly.

Gulp. Are you saying you fired up the chain saw on the ground, and then climbed up the tree with the 'saw still running?

No, I tested it while on the ground then stopped. Gone up in ladder and tried cutting branches.

Cool. I knew you did - 'cos you are still alive.

sujsuj

Strange results from RIOBI chainsaw again!.

I used couple of days RIOBI for cuttin branches connecting three extensions one by one.
Did 50% work already. Now started strange behaviours again.
RIOBI works randomly, else results in triping power of breaking  13A fuse..

Status is very random, sometimes it works other times it is not working.
Really troubling me..Today I opened one RIOBI to see if any issue inside
Couldn't see anything specific. Not sure how it loose capability after such a small use..?