PK200 Table Saw Accident

[SammyQ]

Regarding the earlier '5 bob note' comment re NVR switches: I have had a NVR-controlled planer START UP as I walked away from it 10 seconds after I had switched it off, picked up and sorted the wood.....

A bit of web research revealed dust inside the cover as a possible culprit, but there did not appear enough therein to unequivically say"that was it". Since that memorable day, I have ALWAYS unplugged before playing with my 'toys' rotating sharp bits. I have been known to employ bits of hardwood as a paranoid/safety 'belt and braces' item.

Take care everyone - when I worked in industry, EVERYONE working on or near a 'down' machine placed THEIR padlock on the trip: sparks, operator, foreman, engineer, inspector. Frustrating sometimes (teabreaks) to find a key holder, but dead safe.


Sam

 

[Digit]

Too true Sam. At Vauxhaull motors I got caught with 750 volts when my boss reconnected without telling me.
The foreman said 'you can't talk to him like that!' :lol: :lol:

Roy.

 

[Jake]

The 13A fuses are there to protect the wiring. The concept of a ring main is dependent on diversity and load distribution, and in particular avoiding heavy point loads which might be unevenly distributed. If you stick an unfused socket outlet near to one end of a ring, you have the potential to overload the cable on the short side of the ring which will carry most of the current. Effectively, that means you have one 2.5mm wire which is only protected by the 32A MCB at the CU. The insulation on 2.5mm2 t&e will fail at around 30A - leaving you with a potential fire.

You seem to be suggesting that you could install a mini-CU on a ring main, with a 16A MCB feeding a radial? I don't know whether it would meet the Regs (I don't have my copy handy), but I don't see what advantage it would offer over the (definitely approved) dedicated radial.

I think it would be better advice generally to stick to the simple and straightforward "If you want to install a BS4343 (commando) socket outlet, you have to put it on a radial circuit wired back to an MCB (of less than 20A rating) at the consumer unit. You cannot safely put it on a ring main."

 

[Digit]

If you are going to argue that Jake the same argument would be exactly the same if you plugged a 3KW heater into a 13 amp socket nearer to one end of the ring than the other!
As I said, practicality as against strict adherence to rules. Like being nicked at 36mph through the centre of Birmingham at 3.30 in the morning!
Or like the gas regs, your gas boiler must be connected to the supply by a competent engineer, what's competent look like, never heard of Corgi engineers being prosecuted for causing deaths? But they were [/i]qualified.
Qualified but not competent!

Roy.

 

[Jake]

Roy, in your example the wire is protected by a 13A fuse which restricts the maximum point load to ... 13A.

It is not safe to use BS4343 sockets on a ring main, that is not a minor detail like you keep making out - it is dangerous to do so.

 

[Digit]

I disagree, my reasons are thus. Working from the 16 regs a spur off of a ring is, as I know you will agree, legal.
Most spurs are fitted with a socket outlet, alternatively a fixed spur outlet with its own fuse is frequently used for fixed appliances. C/H installations are frequently wired so.
The 13 amp fuse will blow, allowing for manufacturers tolerance at 20 amps, a 16 amp MCB will trip, within tolerance at, 20 amps.
The response time of an MCB is vastly superior to that of a cartridge fuse, thus reducing significantly the possibility of serious damage to your machine,which would you prefer to connect your machines via?
The current regs are No 16, therefore there were 15 previous regs. They have always lagged behind wiring practice, eg the RCD was being installed by me long before they became a requirement, likewise MCBs.
Please explain why a 16 amp MCB should be dangerous when a 13 amp fuse is considered by yourself not to be.

Roy.

 

[Jake]

Roy, you didn't mention a seperate MCB when this conversation started - you just told the guy he could replace a 13A socket outlet with a commando style plug. Can we just get it straight that was wrong.

Then we have the later diversion of your proposal for an odd mini-CU on a ring main with a 16A MCB. It is certainly safer than just sticking the socket in the ring main unprotected, but I don't see the advantage over running a proper radial back to the CU - which is definitely an approved and safe circuit. I do know that I am not competent to invent such non-standard circuits.

 

[Little Ern]

The electrical debate is well beyond me but my workshop CU has only 2 possible circuits from it so I don't think I can create a dedicated radial supply without installing a new CU (more expense!). If a fused spur off a socket is also a no - no then it will probably mean a smaller saw than the 3HP SIP jobbie.

 

[Jake]

If you are capable of wiring Roy's suggestion, you are also capable of changing the CU for one with a couple or three more ways (one, and a spare or two, always have spare ways!), and adding the radial. The cost difference will be next to nothing.

Have people reported 13A fuses blowing on that particular SIP on start-up, then?

 

[Digit]

Granted Jake. Simply because for all practical purposes it is not needed, If I were doing the job myself I would either run a radial main or a sub MCB.
But a 16 amp socket as discussed is not dangerous.

Roy.

 

[Digit]

A fused spur off of a socket LE is legal, I haven't read the regs for some years but normally what is not specified against is legal.
An example, we were installing RCDs long before they were mandatory on the basis that they were not specified against.
As I pointed out, a 16 MCB will fulfill the same role, more effectively than a 13 amp fused spur.
If it is not specified against then you may do it, from a pure safety viewpoint it is vastly safer than a 13 amp fused spur.

Roy

 

[Jake]

I am interested in whether the SIP 3HP saw does actually blow 13A fuses on start-up in practice. My 3HP tablesaw doesn't but it has some fancy electronics, but nor does my 3.4HP p/t, which is just a plain old induction motor. Loads of manufacturers seem to routinely say a 16A supply is required, when it isn't in fact necessary. Maybe the SIP is cruder, though.

 

[Slim]

I am interested in whether the SIP 3HP saw does actually blow 13A fuses on start-up in practice. My 3HP tablesaw doesn't but it has some fancy electronics, but nor does my 3.4HP p/t, which is just a plain old induction motor. Loads of manufacturers seem to routinely say a 16A supply is required, when it isn't in fact necessary. Maybe the SIP is cruder, though.

No, it doesn't.

 

[Jake]

There's a simple solution, then.

 

[Digit]

Ah, but my flaming SIP 10 incher does!

Roy.

 

[Slim]

Ah, but my flaming SIP 10 incher does!

Roy.

I thought it was the 10" model Jake was talking about. It is, after all, the only SIP with a 3HP motor. Mine does not blow a 13amp fuse.

 

[les chicken]

My SIP 10 cast iron jobby runs quite happily of a 13 amp plug. One thing to check is that the drive belt is not tensioned up to tight as this will cause the fuse to blow on start up.

Les

 

[Rknott2007]

my sip has never blown a fuse, whereas my previous saw, scheppach, did it everytime without fail.

 

[Jake]

It's whatever saw Little Ern was considering - he last referred to it as a 3HP SIP, and I was too lazy to go back and check earlier posts (and I still am).

 

[Digit]

So what did I do to get a SIP that eats fuses I wonder? :lol:
Mind you, I wouldn't change it.

Roy.