corbin dunn wrote:
On Sep 11, 2013, at 12:43 PM, Bruce EVangel Parmenter<[email protected]>
wrote:
I did a 120v 20a timer search. I found plenty in the $10 range rated
at 20A.
So, as Jerry posted, your local hardware outlet should have them. These
are many in large quantities, so the price is low.
Note: their 20A rating maybe really designed for a 16A maximum
continuous electrical load.
IMO eventually under a higher than a continuous 16A load, the timer
would get cooked an stop working. But they are so cheap you could buy
another one, and recycle the worn out one, which is much cheaper than
buying a $100+ timer.
But could cause a fire! Instead, buy the $100 timer.
If the timer claims 20 amps, but is housed in an ordinary single-gang
plastic electrical box with plastic "switch" cover, the only way it can
actually handle 20 amps is if it has a mechanical contact (switch or
relay). Any of the electronic ones will use a TRIAC, which has a 1.5v
voltage drop. 1.5v x 20a = 30 watts; there is NO WAY to dissipate that
much heat without a metal box, heatsink, or fan.
Your typical light dimmer uses a TRIAC, and 5 amps is about the most
they can stand without getting very hot.
--
A good scientist is a person with original ideas. A good engineer is
a person who makes a design that works with as few original ideas as
possible. There are no prima donnas in engineering. -- Freeman Dyson
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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