RCD Tripping from Power Saw

[Andrewbullie]

Hi All,

I have a 2400w power saw on 230v which is tripping after about 0.3 seconds. It is running of a 16A RCD with no other devices on the circuit. Could this be caused by a high current demand at the start up or is it more likely to be something else?

My calculations reckon that it should draw 10.5A, but if it was a short, would it allow the saw to start enough to spin the blade like it is?

PS, I'm not an electrician as you may have guessed but have a limited knowledge.

Cheers

Andy

 

[plugsandsparks]

Couple of questions:
Is it really a 16A RCD or is it a MCB, either way is it a B16 or C16 or D16 (written on the breaker)
If you look at the breaker just write down what it says on it or photograph it so we can have a look see.
Its possible that if on a B16 it could trip on start up even though there is nothing wrong with it

 

[Darkwood]

Are you sure its not an RCBO (Combined overload and earth leakage) as i suspect you mean, What type mcb rating is it (b), (c) etc

 

[Andrewbullie]

It is B16

 

[Darkwood]

deleted ....OP has given more info thus this post isn't relevent.

 

[Andrewbullie]

Further to this it says:

RCCB Protected, then there is RCCB 63A - 30mA, then a B16 (ring main) and B6 (lights)

 

[plugsandsparks]

If you have them, have a look at the instructions that came with the power saw see if it mentions anything about it needing a C type breaker, also have you tried it in the house say on a B32 breaker, like on your sockets ?

Also are you sure its an RCD type breaker, is there a little test button on this breaker ?
cheers

 

[plugsandsparks]

Further to this it says:

RCCB Protected, then there is RCCB 63A - 30mA, then a B16 (ring main) and B6 (lights)

is it just the B16 that is tripping or the RCCB as well?

 

[Andrewbullie]

There is a black button but doesn't do anything when pressed, however, there is a small hole which says test once per month

 

[Darkwood]

Deleted until we have more info'

 

[Darkwood]

Is this a saw with a 13amp plug top? if so did it come with this on or is it a larger saw for which ive given advice on .... and im still unsure what is and what isn't tripping you are not been clear?

You also say ring main ...what makes you think its a ring if its only protected by a 16amp mcb?

 

[plugsandsparks]

Ditto, suggest OP tries the saw on another supply

 

[Andrewbullie]

It is a standard 13A plug 12" mitre saw my a manufacturer of 'Sip'. The supply to the shed is via 2.5 T&E to the RCCB. From there the ring runs via a B16 breaker and it is this which trips each time. The fuse in the plug is ok.

- - - Updated - - -

I am planning on taking to work in the morning as we have an empty factory unit with various supplies available

 

[Knobhead]

Is this in the same building you were going to have demolished?

 

[Andrewbullie]

It is the building that housed the inner building that we are planning on being demolished.... Either you have a good memory or you looked at my previous posts! :icon6:

 

[Silly Sausage]

Can I suggest that you post as many pictures as you can. of the DB, breakers/RCDs/equipment/tags on the gear etc etc........

 

[Andrewbullie]

Will do, do I have to upload the picks to Flickr first and then input URL?

 

[Darkwood]

It sounds like it tripping on inrush then, a C type may cure this ( no promises) but is only an option if the ELI would comply to regs otherwise plug into a Ring main elsewhere and i suspect you wont have any problems as this other Ring should have a 32a mcb covering it which is the problem with the shed as you cant upgrade the mcb to larger size due to supply cable size.

 

[Darkwood]

Plug into a standard ring main i believe this will cure your problems ...the shed set-up dosn't sound like you can adapt it to work and yes the motor inrush on the 16b mcb sounds like your culprit.

 

[Andrewbullie]

So if I don't find a problem at the workplace tomorrow then I could upgrade to 32a and place cable with 6mm?

 

[Darkwood]

So if I don't find a problem at the workplace tomorrow then I could upgrade to 32a and place cable with 6mm?

You mentioned you supply to shed is 2.5 if im right this means you cant upgrade this mcb without upgrading the shed supply and i wont make suggestions because it really needs to be looked into on site .. a little bit of missed info' could end up with you getting incorrect advice.
Its clear (no disrespect meant) that your not an Electrician as you struggle to identify the protection devices so i advice you get someone to have a look what it would entail to increase the mcb rating to the circuit as it may require a new shed supply etc etc..

 

[Geordie Spark]

Is this in the same building you were going to have demolished?

No .......... you're getting confused with the 3,000+ Clubhouse. :jester:

 

[Andrewbullie]

Well, I took the saw in to work today and tried it...... Ran sweet as a nut!!

So, it looks like I need to upgrade my supply. I had a word with one of the electrical guys at the calibration site this afternoon and he reckons change from B16 to a C20. I since checked the supply and discovered that it is actually 2.5 SWA cable on a run of approx 8 meters not twin & earth like originally thought.

 

[plugsandsparks]

How is the shed/garage fed from the house? Does it have its own breaker or is it fed from the sockets via a spur or something. You may end up passing the problem further up the chain as it were. C20 is worth a try, there is the little issue of having a good enough earth to make sure it trips when required if there is a fault. Could one of you electricians at work do a drive by and measure the Zs from a socket in the shed, will only take a minute, then at least you and your shed are safe.

 

[Guest111]

Obviously a "drive by" doesnt mean the same in your area as mine,if it did he wouldn't need to worry about his electrics afterwards lol:66:

 

[Andrewbullie]

It's straight in to the board on its own breaker, so I'm guessing that there shouldn't be a problem