Electric Setup for Portable Saw and Router Table

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richms

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#3038199 17-Feb-2023 15:44

There is a strong case that any switch on the appliance should be double pole, already the case for caravans and portable structures and in one of the AU states for powerstrips etc. This is because of polarity reversal concerns on an upstream extension cord or similar making entire things live when "off" with single pole switching ending up on the neutral. The magnetic switches I got off aliexpress switch both of them, and downstream of that is just a powerstrip which already has DP switching in it as its a current one that is made for the whole of AU market.

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Tick

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#3038264 17-Feb-2023 16:30

richms:

There is a strong case that any switch on the appliance should be double pole, already the case for caravans and portable structures and in one of the AU states for powerstrips etc. This is because of polarity reversal concerns on an upstream extension cord or similar making entire things live when "off" with single pole switching ending up on the neutral. The magnetic switches I got off aliexpress switch both of them, and downstream of that is just a powerstrip which already has DP switching in it as its a current one that is made for the whole of AU market.

Caravans and portable structures tend to have a metallic non-grounded structure that is connected to electrical negative and the possibility of a neutral being connected to it is not non-zero. A double pole switch is required to ensure safety from both live and a floating negative/neutral voltage. The Australian requirement for a double pole switch on all outlets apply to construction and demolition sites where it is common to accidentally damage cables. Double pole switches are definitely "safer" than single pole switches, however this is an additional safety feature which isn't required in everything and would bump up costs, complexity and in my experience, adds another potential point of failure for no realistic gains. The outlets are installed by a certified and qualified professional and they are not considered easily accessible and modifiable by the unintentional user. You could argue that wearing a construction helmet at a swimming pool would be safer. If it helped you feel safer when swimming, go ahead, I won't discourage you. I just don't sell snake-oil myself.

richms

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#3038281 17-Feb-2023 17:21

There were a whole lot of powerstrips and timers for a while sold at jaycar with a note that it was not for sale in one of the states because it lacked double pole switching, and now almost all the timers at bunnings say double pole on them, all the arlec smart sockets have 2 relays in them one for each pin. No additional costs really incurred at all with that change in manufacture. Can still get a crappy cheap powerstip that is crap and cheap with a switch on it.

Plenty of clowns putting plugs on things that could lead to polarity reversal, at least if they swap earth and neutral then it will trip RCDs if they have one, but live and neutral will do nothing obvious unless someone plugs a tester into the end of it. Sure, on a site then test and tag should pick that up if they actually do the testing before putting a new sticker on the cable every 3 months but we all know how that industry works.

Richard rich.ms

MikeAqua

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#3039971 21-Feb-2023 11:19

@tick thanks for your really helpful and detailed reply.

I was envisaging an outlet and plug that use a ring-lock to secure the plug so it won't fall out. The outlet is to be mounted on the ceiling or high on the wall at a particular point.

I understand what you're saying about circuit breakers. I do my own DC work on my boat and cars and use the same principal there (and daisy chaining of non-critical loads).

I can see your suggested approach to outlets simplifying matters. I wanted a nice big chunky control to switch between powering the saw and router. In hindsight that's probably overkill as I'll have e-stops as well as the switching on the devices themselves.

And I'll definitely be getting a sparky to help me with this. I'll do all the mundane things, like cutting holes and installing conduit.

Mike

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