heat blanket running at 240V

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erlabs
Posts: 17
Joined: Thu Jun 07, 2007 11:58 am

heat blanket running at 240V

Post by erlabs »

So I just got my heat blanket and considering the size (15' wide) I had it spec'd for 240V. Looking at my 240V recepticle though I'm not enitrely sure how I am supposed to hook it up. On the recepticle here are three leads, 2 hot each running 120V and one ground. However the blanket only has two leads and I am assuming one has to be hooked up to ground to complete the circuit.

How does 240V work? Is there a difference between single phase 240V and the recepticle I have? If I short the two hot leads does that make the 240V? Looked at the article about the heat blanket and saw L1 and L2, is L2 ground?

Material scientist in bad need of electrical help!
dbtahoe
Posts: 106
Joined: Sun Feb 18, 2007 7:57 pm
Location: Lake Tahoe

Post by dbtahoe »

Don't you LOVE this stuff. I just spent the last week learning about PID's, SSR's. Didn't even hit the radar that the blanket hookup wouldn't be straight forward. I look forward to reading someones input.

Got snow up on the peaks this last week. It's coming fast!
doughboyshredder
Posts: 1354
Joined: Mon Sep 17, 2007 7:37 pm

Post by doughboyshredder »

One leg of the 240 goes to one wire. The other leg goes to the other wire. The ground is unnecessary. 115v is one hot leg (115) and a neutral. 240 is one hot leg (115) and another hot leg (115) to give you 220-240 volts. There is no neutral in a 240v system. If you take an electrical meter and put one lead to each hot leg you will read 230 +- if you take your electrical meter and put one lead on ground and one lead on a hot you will have 115v.

L1 stands for LINE ONE L2 stands for LINE TWO
Do not hook the ground up to your blanket.
erlabs
Posts: 17
Joined: Thu Jun 07, 2007 11:58 am

Post by erlabs »

cool thanks doughboy! makes a lot of sense now.
G-man
Posts: 600
Joined: Sat Mar 25, 2006 3:58 pm
Location: northern sierra nevada

Post by G-man »

Hi erlabs,

You wrote:
How does 240V work?
doughboyshredder did a good job of explaining. Here's an additional wikipedia page in which the first couple of paragraphs spell it out in even more detail:
http://en.wikipedia.org/wiki/Split_phase

The only thing that I'd add is that you connect the ground wire of your 240 recepticle to your press frame and to any other metal layers that you might be using, such as an aluminum pressing layer. That way, if your system should develop some sort of short circuit (lots of pressure and sharp edges), your body won't become the current's path to ground.

Good luck,

G-man
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