I'm in need of an, um, extension cord that, when power is requested by the
attached device, an additional outlet on the box goes live.
The purpose of this plan is to provide power to an auxiliary exhaust fan
when the fume-generating equipment is switched on.
The scheme seems infinitely simpler than hooking up wiring to the primary
Any suggestions would be welcome.
Most woodworking shops have stuff like this, for exactly that purpose:
turning on a dust collector when you power up your table saw. Check out
places like Lee Valley (http://www.leevalley.com) and other woodworking
Richard, how would he use a VOLTAGE operated relay to do what he wants
He needs a CURRENT sensing relay, doesn't he?
Here's a "fancy one" which looks like it'd have enough range and
capacity to sense the first unit's current draw and power up the second
But it does seem to me that this $20 device from Sears will give
eggsackly what he wants:
Looks to me like that's just a power-strip
witha strange configuration.. IOW, if it's
on power is available to all three devices,
and if it's off, there's no power.
I thought OP was looking for something that
would supply power to the other devices
only when the primary was actually DRAWING power.
I'd be willing to bet you $50 to the 501C charitiy of the winner's
choice that your "Looks to me" is dead wrong, Goedjn.
The link I posted may not work, but going to www.sears.com and searching
for 00924031000 will bring it up.
If you zoom in on the photo you'll see the top outlet is labeled "power
tool" and the bottom two are labled "accessory - accessory".
Plus if you click on and read the "Reviews" you'll see users describing
doing what the OP wants to do. The only limitation might be its 15 amp
Wanna place your bet? <G>
Mount contactor inside and outlet box outside of tool cabinet/base. Splice
contactor coil in parallel with the tool's switched power. Splice tool's
incoming cord power into one side of contactor poles, outlet to the other
side. Or, use separate AC circuit for contactor supply if you do not want
to load the tool's cord. Now the outlet powers on/off with the tool
on/off, but the outlet does not load the tool's switch.
But Richard, that's not what the OP said he wanted. To wit:
"I'm in need of an, um, extension cord that, when power is requested by
the attached device, an additional outlet on the box goes live."
Note that it reads "requested by", not "when someone flips the power
swith on the tool."
And the OP continues, "The scheme seems infinitely simpler than hooking
up wiring to the primary device."
Your suggestion that "hooking up wiring" stuff, right?
Hair splitting an RCH I freely admit, but that's what engineers do for
fun, isn't it? <G>
Is the device at the far end automatic, or is this
"requests power" event manually induced? THe usual
technique is to replace the switch for the equipment
with a DPST switch. (or just put the power supply
through another DPST switch, in which case
the fan would run anytime the power is available,
reguardless of whether it's being used.
Depending on what the
"fume generating equipment" is, you probably
can't just find a fan of the same current-draw,
and put them in series. So the last choice is
to use a current-sensing relay like this one:
Thanks. I finally found one. It seems as if you flip the switch on the
switch and power is delivered to the outlets on the box, one of which can be
the dust collector.
I want something such that when I turn on device #1, device #2 gets supplied
power. I don't want to make an electrical connection directly to device #1.
I saw one done in a serious fashion, for a different but similar
The person used an old air conditioner contactor, and when he
powered up, a transformer got power too, kicked on the contactor.
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