Saw trips garage circuit - overloaded?

[RL19]

Hi 

we have recently had a new 35kw Worcester boiler fitted to replace two old 15kw boilers in the garage.

Last night trying to run a 1200w circular saw off the same garage ring the main fuse in the consumer panel kept blowing every time I tried to power up the saw. Never had the problem before. Boiler was running at the time. House is relatively new c16 years old so general wiring electrics etc are in good order

Question: is the garage circuit now overloaded and if so what are my options and rough cost implications? Thanks a lot 

 

[kerching]

Is it a 

fuse

MCB

RCD

that 'blows'

WB Boilers only take a couple of amps so i doubt if it is overloaded

turn boiler off at its supply and try again

my money is on it being an RCD that has tripped and there is an earth fault on the saw possibly caused by being left in a damp atmosphere

BUT i have not been to Church yet so i may well be wrong

more,info needed really

 

[Andy™]

motors use a lot of power on start up. its possible that the circuit is not overloaded as such, but because of the load currently on it, the start up power required is more than the fuse can take

but do you really have fuses, if its fairly new, i would expect MCB's, and fuses dont tend to blow too often on situations like yours, MCB's will

 

[RL19]

Thanks guys you are right it is a MCB and relatively new - was aced 5 years ago

I tried the saw in the kitchen (wife was not amused !) and it worked fine 

if the MCB keeps tripping is that an issue with the MCB? What can be done about that? 

Thanks i I know it is a bit tricky not being able to see it but just trying to get a feel for what might be done as need to be able to have decent power the garage 

 

[Andy™]

the MCB is doing exactly what is was designed to do. depending on your wiring, it may be possible to fit a different type of MCB, but there are too many variables to go over on a forum. best solution is to get someone to come look at it and see whats the best solution

 

[NozSpark]

You said that the electrics are in "good order"..... how do you know this? When was the last time that they were inspected and tested?

 

[Rob_the_rich]

you say there is a garage "ring", but that the "main fuse" (now an "mcb") in the consumer unit "blows". But doesn't "blow" the kitchen ring.

Are you sure it is not an RCD? does it have a test button marked T on it?

What else is on the garage "ring"?

1 more post and you can upload a picture of your CU.

 

[ProDave]

Thanks guys you are right it is a MCB and relatively new - was aced 5 years ago

What does aced 5 years ago mean?

What does it say on the mcb that's tripping, is there something perhaps like B16 or B32 written on it?

Was ANYTHING in the garage CU changed when the new boilers were installed?

If you can post a picture and show which one is tripping.

 

[binky]

I would suggest whoever replaced boilers buggered leccy. I have a 35kW combi, it's ona 3 amp fuse, it would only pull 60-100w roughly for the circulation pumps. It might be a fault has occurred that coincides with the boiler change, but did plumber do the wiring, or proper electrician?

 

[Evans Electric]

I agree with Binky , if it was OK before then the boiler guy may have swapped a circuit or MCB .

As said above, what does it say on the MCB   ( B16 ,...B20...B32   etc)     Circular saws often trip breakers with their start up current . 

 

[Blue Duck]

But if it was okay before.....

I doubt the low current of a boiler + the high startup current of the saw would send the mcb over the edge.

Could be an insulation fault that only shows up with the high current of the saw

 

[RL19]

Thanks guys

used the saw all day today and it was fine so it is just at night when the heating, boiler, lights etc etc are all on 

when it triped it was the main RCD switch in the photo rather than one of the indvidual circuits (can't upload photo as it is too big). Thanks for help

 

[ProDave]

So it's the RCD tripping. So it could be a fault with the tool.

Was the RCD there before?  Was it added when the boiler was replaced (might have just been a switch before)

 

[RL19]

Hi Dave no RCD has always been there and tool worked fine all day today 

 

[Apache]

I have a 2200W table saw that periodically used to trip the 16A B curve MCB in winter, but never in summer.

It's now on a 20A C and always fine.

There is nothing wrong with the saw - it's just the inrush. I can quite believe the contribution from the boiler could push it over the edge.

Any thoughts how temperature could affect it?

 

[RL19]

Now got the photo to upload showing RCD switch if that helps 

 

[Apache]

Is it the RCD that trips?

 

[ProDave]

A picture paints a thousand words.

From the original description I thought it was a consumer unit in the garage itself that was tripping, not the main one in the house.

The only way you will get to the bottom of the cause is to get an electrician to do some testing. It could be a cumulative effect of leakage in the saw, and leakage on some other circuit.

 

[NozSpark]

So it's the one on the far right that trips?

IMHO it sounds like you have a fault somewhere,,,, although it could be anywhere

I'd say that you would probably benefit from getting someone in to carry out an inspection and test

 

[Andy™]

so its gone from fuse to MCB to RCD....