[chbot] Electrical Safety

Charles Manning cdhmanning at gmail.com
Wed Aug 20 05:57:47 BST 2014

To add to Robin's worry-list, you also need to consider the DC side
too... DC arcing is a pig as it is not suppressed by zero crossing.

C'mon Richard... live on the edge. That you lived over 30 is just an
accident of time and place. If you'd been born more than 100 years ago
or in 3rd world, odds-on you'd never have graced us with your
presence.... which would have been a loss for us.

On Wed, Aug 20, 2014 at 4:49 PM, Robin Gilks <robin at gilks.org> wrote:
>> I almost hesitate to re-open this old chestnut.
>> I'm considering the purchase of a generator or inverter in the 1-2kVA
>> range and was wondering about electrical safety, especially with some
>> inverter/charger/UPS combinations.
>> I found some products from China on trademe without any obvious claim
>> to meet AU/NZ electrical safety standards. When I checked back on the
>> standards route I was surprised to discover that new imported items
>> may be exempt by a "Conformity Co-operation Agreement" in Section 80
>> Part 2(b) of this document:
>> http://www.legislation.co.nz/regulation/public/2010/0036/latest/DLM2763717.html
>> So referring on to the cooperation agreement I have little idea how to
>> check whether a device I plan to purchase is really safe or not.
>> http://www.med.govt.nz/energysafety/appliances-fittings/electrical-appliances-fittings/core-requirements/international-cooperation-recognition/current-mras/new-zealand-china-2013co-operation-agreement
>> At the end of the day I want to live long and prosper safely through
>> the odd power cut or DIY activity away from mains power. Any thoughts
>> on that? Maybe running an inverter/charger or generator through an
>> appropriately connected RCD is the prudent way to go.
> A lot depends on what part of the system you are trying to make safe.
>  * exploding batteries due to too high a load
>  * smoking inverter due to poorly specced parts
>  * grid-mains isolation (anti-islanding etc) to not kill your neighbour
>  * output voltage being within the range of the appliance connected to it
>  * output waveform being appropriate for the device being powered
>  * earth isolation to prevent dangerous current loops
>  * earth leakage breaker for personal protection and fault detection
>  * insulation appropriate for the voltages present in the system
> For example, I use an electric hedge trimmer running on a small 2-stroke
> generator which has a floating mains output. If I cut the cable, the
> chances of me being across both live and neutral is pretty slim compared
> to livening the cutters if I hit the live on a grid-mains connected
> trimmer.
> --
> Robin Gilks
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