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Re: Price of substrate heating -- Plugging equipment holes

Interesting.  I thought all grounded plugs had ground
prongs that made contact before the hot and neutral prongs.

What I had meant is that the grounded plug has the third prong that makes contact before the hot and neutral. And that a non-grounded plug can plug into a grounded receptacle. Might not have been real clear I guess.

I hear you loud and clear about how poor many house
receptacles are at delivering power -- and most plugs are
very bad too, relying on simple crimps, small contact areas
between metals that tend to film over and corrode with age.
 Truth is though, most purposes, it doesn't seem to matter
much.  Unless you want to a good clean supply of power with
out unnecessary resistance.

It becomes an issue with larger electrical loads too. For our (aquarium) purposes, the only time the receptacle might pose a safety problem is in a larger setup using a lot of lighting. For example, in a large setup with 3 x 175 watt MH lights, some circulation pumps, and maybe 300 watts of heating, there could be maybe 10 amps or so of 120v power drawn. That's enough to cause a loose plug to get warm enough to soften the plastics used to make most molded cord assemblies. The best solution I have found is to use 20 amp commercial receptacles (only about $4-5), which of course assumes a 20 amp circuit, since they tend to grip the plug's blades more tightly over a longer period of time. Commercial 15 amp receptacles will also be better than the 50 cent cheapos that you can find in many hardware stores. It's only a few extra dollars and it really can make a big difference in the safety of a larger setup.


Scott H.

Waveform Technology
UNIX Systems Administrator