Electrical gang in series

CDrew

Hi, question for the electrical experts.

I am cutting plasterboard with a multitool. I want to rig up a vacuum cleaner so that it comes on with the multitool, to cut down on the dust.

My plan is to modify an electrical gang socket so that the cleaner comes on at the same time as the multitool.
The first socket has the multitool plugged in. The second socket has the vacuum cleaner plugged in.

The live terminal of the second socket takes power from the neutral terminal of the first socket. The neutral terminal of the second socket connects back to the neutral wire of the cable.

The vacuum is plugged in and switched on, but won't receive power until the multitool is switched on to complete the circuit.

I'm hoping that both the vacuum and the multitool come on together when the multitool is switched on.

Any thoughts? Am I going to trip the circuit board? Is the vacuum going to run in reverse?

mickdw

Are you running all the current for both devices through the switch of the multiple tool by doing that. Might burn out the switch.

Bruthal

It wont burn out the switch if the OPs idea is to run both items in series, as the total load is now less than the smallest load.

Put a 10 watt cfl in series with a cooker, and the cfl will light when the cooker is on, but the max load will be up to 10 watts and no more,, getting closer to the 10 watts, the more rings are switched on.


Short answer, 2 x 230v appliances in series on 230v cant both work properly.

Risteard81

Get a hoover with power take-off. They are designed for this application and will auto start once the tool is switched on.

Bruthal

As for getting the vacuum cleaner to run in reverse, that takes a bit of tinkering.

CDrew

The vacuum is 1000 watts, the multitool is 300 watts. Are the two devices limited to <300 watts between them?

CDrew

Risteard81 wrote: »

Get a hoover with power take-off. They are designed for this application and will auto start once the tool is switched on.

I'm too tight!

LastFridayNight

Neither motor will get the correct voltage, and each device will be constantly interrupting the others supply. If either tool has a variable output to it's motor, the other tool will be affected by that. If either tool has sophisticated electronics, the results will be unpredictable. Finally, the larger rated tool will attempt to draw bigger current through the smaller tool, quite possibly damaging it.

LastFridayNight

Also, these are available, though very expensive. https://www.amazon.co.uk/Vacuum-Auto-Switch-Box-model/dp/B01LBB3698

Bruthal

CDrew wrote: »

The vacuum is 1000 watts, the multitool is 300 watts. Are the two devices limited to <300 watts between them?

If you put 1000w and 300w lights in series, you get about 230w id say, with the 1000w one operating at 50+ watts, and the 300w one at about 170w.

With motors, its likely the 300 watt tool one might start quickly, and the vacuum cleaner might start slowly. If the vacuum one does start running, the tool motor will reduce in output.

They just wont work right.

Bruthal

LastFridayNight wrote: »

Finally, the larger rated tool will attempt to draw bigger current through the smaller tool, quite possibly damaging it.

The larger demanding appliance wont do that to the smaller one. It just doesnt work like that.

Seve OB

Just get one of these guys.
One of the coolest things I've ever bought.

https://www.festool.ie/products/dust-extraction

Bruthal

Lightly based on the same thing roughly, i did a project where 2 12v motors on rear wheels of a childs tractor would switch between series and parallel by a relay arrangement I setup in it. It was for a 2 speed selection.

When in parallel, it was like having the differential lock on, both wheels fixed at full speed, so while turning, one would have to slip a bit on the ground.

In series, when one motor slowed, the other would speed up.

If the wheels were off the ground and you slowed or stopped one from turning, the other would speed up proportionately. The one which had its rotor slowed or stopped would have a proportional lower impedance, so the other would speed up, as more voltage would be applied to it. So in series, they acted as a proper differential.

CDrew

Thanks, people (Bruthal especially), I'll suppose I'll carry on clambering down the stepladder to switch of the vac. Or maybe run a remote on/off switch for the gang, and use that to switch on/off both multitool and vacuum.

Tenshot

You can get SmartPlugs that are designed for exactly this. Here's a couple on eBay and [url=Amazon UK.

And here's a demo (original YouTube link with desc)

Alternatively, get a pack of those cheap remote-control plugs (usually €20 for four) that keep coming up in LIDL and ALDI and run the vacuum off that, then use the remote control to turn on the vacuum when needed.