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Oops! (Transformer voltages)
Should have done a little proofreading on my own message... please ignore
the numbers and use THESE instead (250 watt heater, not 200 watt heater).
What I said yesterday was completely true and consistent for a 200 watt heater.
The version I'm posting today is for a 250 watt heater. :)
(I retrofit my post from yesterday)
> If it was a local distributor, ir was probably a 250 Watt, 24 volt cable.
> You should be able to verify it though an ohm meter. Because P = V^2/R,
> a 42 volt, 250 watt cable should have a resistance of 7.1 ohms, while a 24
> volt, 250 watt cable will have a resistance of 2.3 ohms.
>
> > I have searched far and wide, and not yet come up with a 42 volt/200 watt
> > transformer. So, I turn to the collective knowledge of the list:
Ah, this is why I was confused. Frank was confused too! He said 200
watts here!
...
> You can use a LOWER voltage transformer on the same wire, but not a higher
> one (unless you know for sure the wire can take the higher current).
> Without knowing if you have a 7.1 or 2.3 ohm wire, here are the three
> possibilities you might have:
| 42 volt transformer | 24 volt transformer
--------------+------------------------+----------------------------
7.1 ohm cable | Need 6-10 amp xformer | =81 watts, needs 4-5 amp xformer
--------------+------------------------+----------------------------
2.3 ohm cable | (DO NOT USE) | Need 11-15 amp transformer
> Note though the dramatic difference in output power you get from operating
> the 42-volt 250 watt cable at 24 volts. 1/3 the power!
>
> - Erik
---
Erik Olson
eriko at wrq.com