How Unsafe Is it?? Extension leads etc

[Mimmo89]

Good morning everyone,
just wanted to pick your brain.

I'm thinking of building a little "power tools station" in a corner of my garage, hooking several power tools (that would never run at the same time) to an extension lead plugged into the Power Take Off of a small shopvac so that all I have to do is connect the vacuum hose to the tool I'm about to use.

I know the recommendation is to never daisy-chain several extension leads (the PTO of the shopvac would effectively be one) but is it really unsafe? Considering that the hooked tools are all small and with low-power motors - a disc and belt sander, a bench grinder, a pillar drill, a small band saw and a small lathe.

And how unsafe would it be to take it one step further:
- hooking the drill press and the bench grinder to an extension lead
- connect the extension lead to a VFD (I haven't looked at all the ins and outs of this yet or checked if it even is possible with my tools)
- plug the VFD into the extension lead with all the other tools
- connect the extension lead into the PTO of the shopvac?
It'd be extremely useful to have a dial (the same dial) to add variable speed capabilities to the grinder and to control the speed of the drill press without having to change the belts.

Interested to know your thought.
Dom.

 

[SimonStevensCanes]

I'm definitely not advising, but it sounds pretty safe to me.

That said, I will share an anecdote. I had an office in Manchester some years ago in an old mill with lip service paid to modern electrics, we had a very limited number of sockets available. We ended up running extension leads to power the monitors/computers etc needed for a trio of desks. Come winter, we discovered that lip service had been paid to adequate heating so we bought an oil filled radiator for each desk with was lovely and warm, but of course was plugged into the extension leads. This I think was actually relatively safe as each desk had a different supply. At some point however somebody switched around what powered what. Shortly after we tripped the breaker (thank god) and discovered that we'd managed to link all the oil filled radiators through a single extension lead, which had... melted. Lessons were learned .

So it's worth keeping in mind that what you're proposing now sounds safe enough (I am no expert), but in the heat of the moment when you need to get something done, things get forgotten and that's when accidents happen.

 

[Sideways]

Absolute no to your ideas about the vfd.
They should be programmed to match the specific motor connected so you would be continually reprogramming it.
The manual of every vfd will tell you that the motor should be hard wired to the vfd as you can potentially damage the drive running it with no motor connected.
And lastly, vfd's are mostly designed to drive a 3 phase motor, with just a few models specifically able to drive a single phase, single capacitor motor. If you have a mix of single and three phase machines you would need at least two drives.

A smarter idea would be to simply get a radio remote control switch to turn the power to your vacuum on and off from wherever you are and power the tools separately and more directly, not through the vac. You can still have your manifold or whatever for swapping the vac between the hoses to your tools.

 

[Sideways]

Remember, if you turn down the speed of a motor using some variable device, you also turn down it's power and make it more likely to stall. This often makes variable speed less useful rhan you might think.