I have a blog entry written to describe the build of a heated nichrome heated bed, but I'm not allowed to insert it. h t t p://blog.neednow.de/blog/2014/12/27/heated-bed/
Note on electrical safety: any "live" metal - or any metal with uninsulated circuitry nearby - should be grounded: period. It is possible to kill somebody by inducing fibrillation if even a small current occurs across the heart (70mA is enough to cause this: though 700mA is more likely) - a current across the heart can occur simply by holding something with two hands...
While a current this high isn't likely due to the voltage and resistances used in heated beds - electrical mishaps can and do happen. All it takes is for a voltage regulator to fail and the controller board and a larger-than-intended current can be introduced to the system: and while PSUs should produce a steady voltage as required, it is again possible that electrical failure can cause live mains current to enter the system (while unlikely, this is more probable with hand-modified bench power supplies retrofitted from computer power supply units - and as laptop transformers are quite popular, I've noticed and indeed even owned a variety of wan hung low chinese knock-off brands that simply don't have the required protection if something fails)
As such I would suggest that a note be introduced to the page with regards to this and preferably rectifying the notes on "citation needed" - just look at any reliable peer reviewed paper on electrocution or electrical safety (pubmed.com if you have academic access or even google scholar though it's less reliable)
- A bit far stretched for my taste. First of all, heated beds are insulated, they don't expose blank metal to the user. Except perhaps these small connector pads. What you talk here about is more a (theoretical) problem of power supplies in general. If a PSU would "decide" to deliver 110/220V directly on the output, the whole electronics would go up in smoke immediately. Barely a situation where people would start to touch everything with both hands without disconnecting the PSU. Compared to toaster ovens, which are considered to be safe already, heated beds are a lot safer. --Traumflug (talk) 04:40, 16 December 2013 (PST)