RCD tripping with mains saw

[Jack Lawson]

cheers

[The Natural Philosopher]

I knew someone would know the correct terminology.

[John Rumm]

A B20 (which would ok with 2.5mm^2 T&E in most cases), will allow 100A of inrush current. A C16 will allow 160A of inrush.

(your current B16 allows 80A)

What kind of motor is in the saw - is it a loud universal brushed motor, or a quite induction motor?

[James Wilkinson Sword]

Remove the RCD, they're a bloody nuisance as you've found out.

[James Wilkinson Sword]

Fuses don't nuisance trip. Get rid of the newfangled shit.

[Archibald Tarquin Blenkinsopp]

I think the whole point is that they are not supposed to work!

Chopping through the cable with the sharp end of a tool tends to make the presence of an RCD desirable.

Whether it's a 30mA RCD or 300mA RCD that is required can be determined using DNA profiling.

Quite a few users of uk.d-i-y would be fine with a 300mA unit :-)

AB

[ARW]

A 16A or 20A C type type will be OK with that sort of run. No calculations are needed.

A 32A B type will also be OK and will have the added advantage that it will annoy dennis.

[Andy Burns]

I thought you might like to break out the adiabatic equation, until Jack mentioned it was all within reach of the CU!

[ARW]

No need for all that bollocks.

However there is a chance that if the OP lives close to a substation then a short circuit may destroy the MCB. That applies to all circuits at the house.

[Jack Lawson]

snip

It is quite noisy 1600 Watt - so guess a universal brushed motor

[John Rumm]

That is incorrect.

A C16 MCB will have a similar fault trip threshold to a BS3036 15A fuse.

Off you go then...

[James Wilkinson Sword]

Never seen a fuse blow with anything other than a short.

I've never had an MCB or other crap in my house.

[Jack Lawson]

MCB swapped for Type C 32 Amps - job's a good 'un Thanks to all for advice.

[Andy Burns]

32A? Properly you should use 4mm^2 with that.

Could you not get a 16A or 20A type C?

[Andy Burns]

Or make it a very short ring with 2.5mm^2

[ARW]

No-one suggested that you should fit a C type 32A MCB.

[Roger Hayter]

We've established upthread that the 2.5^2 is short enough.

[ARW]

Not short enough for a C type 32A MCB on a TN-S supply that is at the upper limits of it's maximum allowed Zs.

[John Rumm]

If its a short radial with only one double socket on it, then the MCB is only required for fault protection anyway.

[Tim Lamb]

As I was in the workshop this evening I thought I should check my claim about my 9" angle grinder tripping the supply. Er... the MCB is in fact a 16amp B type....

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