Hacker News Reader

Comment by ddingus | Hacker News Reader

It's not about that.

It is all about risk mitigation. When building for long term use and safety, scenarios like a short from something falling are designed away.

Think super cheap insurance. And liability management. People can perform to code and that compartmentalizes damages and responsibilities. Couple that with licenses and it's all public safety oriented.

All of it adds up.

Where risk is higher, say in the parent example, yes. By all means use a product intended to manage those risks.

Costs are marginal otherwise, might as well take the cheap insurance.

View on HN

> It is all about risk mitigation. When building for long term use and safety, scenarios like a short from something falling are designed away.

Then you'd want to install Recessed outlets, Outlet Covers, or GFCI Outlets. Since they're designed to be safer, this simply relies on luck that the conductive object bounces off of the neutral pin and away (which may not occur).

Plus the cost isn't free as has been discussed in this thread elsewhere. It breaks a lot of consumer electronics.

GFCI won't protect against a conductor shorting the neutral and hot. It WOULD trip if the outlet were installed with the ground up,and a flexible conductor, say a necklace, fell between the plug and the receptacle.

Yes, recessed or covered receptacles would be a better option, for some values of better. I mean, most people wouldn't accept covered receptacles in their living space because they are "ugly" and would prevent many pieces of furniture from being placed in front of the receptacles (which by code are spaced every 12 feet at the most). And recessed receptacles are going to be a tight fit in most existing residential boxes. Forget smart devices fitting recessed, it's hard enough to fit those into regular boxes once you add some wire nuts back there...

So, yes, there may be some more effective options, but installing devices ground-up reduces a not uncommon hazard without resorting to changing out boxes or adding covers to everything.

I am consistently amazed that it all does "just fit" into a standard residential box.

Sometimes the effort required is crazy, but given that effort, the stuff actually does go in there.

Did someone do the math on all that, or was it more empirical, or?

Anyone know?

Code makes the minimum calculation - as to how it originally came about I would guess a mix of empirical (committees working with various sized boxes as they work on NEC revisions) and then math to have a formula/table for the real world.

There are wire fill factors in the NEC - basically if you have a junction of a conductor of this size (gauge) then it must have this many cubic inches to go with it.

The simplest outlet (a receptacle) would have 2 conductors (hot and neutral) and those each require a certain number of cubic inches based on their size (12AWG and 14AWG being the most common). The cubic inches of a box are typically stamped on the box and the amount of conductors ('wire fill') must be below the box capacity. Ground doesn't (didn't?) count in the calculation as it shouldn't carry current normally so it's not a conductor.

If you've worked in a box at or near capacity (especially with a AFCI or GFCI/RCD) you will always put in a larger box given the chance.

Reply on news.ycombinator.com