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Old 12-12-2008, 11:55 AM   #1
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240V Electric Heater install - 3 wire vs. 4 wire?


I'm installing a 240V 40A electric garage heater. I expected to wire 2 hot (blk/red), neutral (wht) and ground (grn) but the heater only has 3 lugs. The ground lug's wire hole is much smaller than the hot lugs. Is this a pure 240V install where both neutral and ground are not needed? If so is the neutral/ground wire a smaller gage than the hot wires? I was going with 6-8 Gage, OK?

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Old 12-12-2008, 12:22 PM   #2
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240V Electric Heater install - 3 wire vs. 4 wire?


Does the heater draw 40 amps, or does it require 40A protection? Can you post the model number. You are most likely correct. It is a three wire connection(hot, hot, ground). The ground will be a reduced size(most likely 10AWG)

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Old 12-12-2008, 01:15 PM   #3
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240V Electric Heater install - 3 wire vs. 4 wire?


Ouellet Model# OASU10000T Specs show: Volts=240; Amps=41.67; Watts=10,000; BTU=34,120. For wire I'm thinking of using 8/8/10 gage (hot/hot/ground) unless 6/6/10 is recommended.
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Old 12-12-2008, 01:40 PM   #4
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240V Electric Heater install - 3 wire vs. 4 wire?


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Old 12-12-2008, 02:07 PM   #5
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240V Electric Heater install - 3 wire vs. 4 wire?


The unit draws 41 amps. You need a 60 amp breaker. #6 wire required.
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Old 12-12-2008, 10:14 PM   #6
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240V Electric Heater install - 3 wire vs. 4 wire?


I just purcahsed same heater and came on here looking for help. i plan on pulling wire from my main panel to my attached garage. it will take about 90 feet of cable for this. For that reason i think i will do a 100 amp lug panel in garage with a couple extra future circuit capacities. i have not pulled cover off my heater but is this correct that it will only have 2 hots and a ground?? No neutral?
I am thinking 2/2/2/4 aluminum for run to lug box then 6 awg for panel to heater 60 amp breaker.
i will have electricain make final connection but because of complexity of cable pull trying to save some $$.
Most of the equipment i have serviced installed in past ( vacuum sytems and air compressors for denatl offices) used 2 hots neutral and ground. lack of neutral seems odd but i can understand why maybe its not used.
Can someone clarify for me? Also does the 2/2/2/4 aluminum sound like good choice?
Ryan

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Old 12-12-2008, 10:24 PM   #7
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240V Electric Heater install - 3 wire vs. 4 wire?


[quote=ssscamaro;197351lack of neutral seems odd but i can understand why maybe its not used.
Can someone clarify for me? Also does the 2/2/2/4 aluminum sound like good choice?
Ryan[/quote]

I believe the the leg that is out of phase is used as the neutral.

I had an addition done a couple years ago and they used the 2/2/2/4 alum. to feed a sub panel with a 100 amp breaker in the main.
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Old 12-12-2008, 10:49 PM   #8
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240V Electric Heater install - 3 wire vs. 4 wire?


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Originally Posted by ssscamaro View Post
lack of neutral seems odd but i can understand why maybe its not used. Can someone clarify for me?
Neutral is only needed in this situation if there were a need for 120v in an appliance such as with an electric range which has both 120v and 240v loads. For a straight 240v item, no neutral is necessary and would not likely have a connection point. You do need the ground though.

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