Wire up some AC Kill switches


Currently we are powering the workshop from a single x2 extension. The only remote way of killing power to the machine is to remove/turn off the source plug (in the fab area). Some machines have the glorious big red button for stopping blood mode, but it would be safer in general if we could have some system to cut power (Ideally something that we can transport to new place too).

Main killswitch: cut off all power to workshop. Ideally located in an area outside/in entrance to workshop for 3rd parties to interfere in an emergency.

1-to-1 killswitches: not as important as the above, but still good to have. some machines do not have their own safety switches (or they are not great). Consistency here is key for safety in my opinion. These switches are there to help, therefore looking for that big red button that is the same for all is much better than remembering that tool xyz’s switch is under the tool.

Kill switch I have in mind is something like this.


  1. How easy/hard/safe is it to get this sorted?
  2. Is our current extension set up ‘safe’? e.g. extension+high draw from 2 machines > amperage/fuses
  3. I found two reels of electrical wiring, so should only cost what ever the buttons cost right? Or is there additional hardware that needs to be bought (wire terminals/safety things)
  4. Any comments/suggestions/blockers?


@mattyyey is the man to speak to


1: Not very hard, the main kill switch is likely to be the most challenging (we’ll need an official sparks to check everything we do - I believe we have a tame one in the gang)
2: Has it caught fire? What sort of current is being drawn (typically and worst case)?
3: There should be no additional hardware required
4: It’s a good idea.

My only concern is move related. These switches should be wired into the electrics in the new space and wall mounted, so shouldn’t they be fitted as part of the refurb?


There are a TONNE of regulations about workshop safety, and just fitting a safety ad hoc could lead us to falsely assume we have done the right thing. Some of the things I’ve read recommend a switch per item of machinery.

Is there somebody at the council who looks after school workshop safety we could talk to?


Not yet, just being proactive instead of reactive :wink: Im not sure on what the typical draw is with 2 machines, but I just know that using extension reels, you need to be careful.

Yeah, this is why i was tippy-toe on (3). Unsure about rules/laws and if any official inspection/costs will be needed.

Switch per item is good practice and suggested anyway. Not sure what the official say is on this. If my memory serves me correctly (and what i based my original post on), school shops have a cut out per item and a teacher button for the whole room (key lock, although we shouldn’t need a lockable one?)

Either way, anything is better than the current set up right?


If the contractors wire it as we asked them to then we should have multiple sockets per machine in the new workshop and be able to fit BROB’s to whatever we want. Ideally there shouldn’t be anything on an extension lead that isn’t a radio or a couple of phone chargers.


funny you should mention this



What are BROBs? because my google search suggests it isn’t this

Do we have plans for where these sockets are, and how they are wired up? Also was a master socket planned previously to turn the machines off remotely? If so, can I see them please? I will try to merge it with my model.

[*] I don’t fully remember the initial discussion about power, as I don’t mess with AC myself (and we had an electrician with us at the time).

Some tools will be ‘plug and play’ though, due to them being mobile. e.g. the table saw. This is why I designed the tablesaw station to have wheels.

Edit: I thought I was replying to a different topic (of similar content). Regardless of plans of where plug sockets are in the new space, we still need these ‘dead man’ switches


BROB = Big Red Off Button, or dead mans switch if you prefer.

We basically told the guy in charge of the sparks that we needed many sockets, at sensible bench heights all the way around. I’m not sure anyone specifically mentioned dead mans switches but he was told it was going to be a workshop so he might have figured that out himself. It’s possible @mattyyey may have mentioned it since he was talking to the guy. I only really spoke to him about upstairs and moving the lighting / power truss to use for PA / projectors etc.

I’m not going to pretend that 9:30am exists to me on a Sunday, unless it’s from the wrong side, so if you manage to make it can you take a lot of pics please? TA.


Confusing x-talk here, see - http://discourse.hackoldham.com/t/x-post-measuing-and-double-checking-new-space/415

Please try to keep comments in the right place. Else i might lose track of what/who/where things were said. This thread is intended for the discussion/plans to fit a standard set of kill switches to the machines (similar to what the router table currently has)

Ok, relating to the new space. I will note down good locations of a shop kill switch. Current space and tools should ideally have their own that are accessible and standard imo (this is irrelevant of current/new space they are in. These would move with the tools)


within a workshop, if the machinery is fixed - or is supposed to be fixed / unmovable - then the workshop should have its own master KEY CONTROLLED switch. Then each equipment should be wired in its own isolator. This doesn’t need to be lockable, but might be an idea for some things like the saw (thinking of wandering kids here). Yes there are lots of regulations on this, but it all comes down to how you class the workshop… A workplace? a domestic environment (coz hobbyists) ? or more likely given how this group functions, a commercial building. The latter has quite a few regs.

Either way to protect yourself incase of inspection, I’d have a key controlled master, and each item having its own kill button, all wired in (no plugs), not off an extension (the cable is supposed to be calculated to the max output of all the machines on at once), finally make sure the power cables you use are covered by an RCD. It might even be a good idea to have the workshop on its own mini distro board so if it blows, it wont effect the rest of the building. There’s also regulations about access control (hence keyed master) and training for use of equipment and all that, but thats more a risk assessment thing…


Hey @mattyyey good to see you, you should really come check out the new space the council have now fitted out the electrics including emergency stops, and we have a H&S consultant coming on on Monday to point us in the right direction.