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Old 08-07-2010, 10:28 PM   #1
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Multi-tap warehouse lights


I bought some used multi-tap high-bay lights for use in my workshop. The taps are common, 120,208,240,277. There is a housing ground.

I have residential 240V service - can I use one leg of my 2 120 volt hots on the common & the other leg on the 240 tap? The common is open to ground.

I'd like to avoid the 120 volt tap as power use would be higher. If I have to use 120 volt, I presume I would use my panel neutral for the common.

Thanks

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Old 08-07-2010, 10:34 PM   #2
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Multi-tap warehouse lights


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Originally Posted by JackDuich View Post
I bought some used multi-tap high-bay lights for use in my workshop. The taps are common, 120,208,240,277. There is a housing ground.

I have residential 240V service - can I use one leg of my 2 120 volt hots on the common & the other leg on the 240 tap? The common is open to ground.

I'd like to avoid the 120 volt tap as power use would be higher. If I have to use 120 volt, I presume I would use my panel neutral for the common.

Thanks
If this is in the detached garage yes you can able use it.

here the way it hook up.,

The 240 volt lead will go one of the hot conductor { red or black conductor } while the "COMM" is on the other hot conductor.{ red or black other conductor otherwise a remarked white cable will work on this useage.

What wattage it have there ?? If 400 watts MH or HPS on 240 volts you can run many as 8 luminiares on 20 amp 240 volt circuit.

If other wattage let us know.

And is this panel is a subpanel type ?? if so you can not use the lumiaire grounding conductor to netural that is a no-no. it have to go to ground bar or bare or green wire only.

Merci.Marc

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Old 08-08-2010, 09:22 AM   #3
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Multi-tap warehouse lights


Many thanks - yes its a detached garage with sub-panel. Good point about ground vs neutral.

Last question - can I leave one of the hots permamently "on" & just switch one hot leg?
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Old 08-08-2010, 09:38 AM   #4
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Last question - can I leave one of the hots permamently "on" & just switch one hot leg?
Just get a 2-pole switch.
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Old 08-08-2010, 10:40 AM   #5
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I'd like to avoid the 120 volt tap as power use would be higher.
Completely untrue. The usage would be exactly the same.

The advantage to using 240v is that you can have more fixtures on a circuit.

As Proby said, use a two-pole switch.
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Old 08-08-2010, 11:28 AM   #6
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Multi-tap warehouse lights


Subject to the quality of the insulation (which is rated in volts) the same pair of wires will with the same degree of safety carry about twice as many watts at 240 volts as at 120 volts. Namely the wire (conductor) is rated in amperes. When wired up for 240 volts the fixtures draw about half the amperes each compared with 120 volt wiring to draw about the same wattage.

Also, the voltage drop in a given wire (for a given resistance) is expressed as a number of volts versus so many amperes, not the percentage of volts. Of course dropping five volts out of 240 is less of a percentage waste compared with dropping five volts out of twelve.
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Last edited by AllanJ; 08-08-2010 at 11:33 AM.
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Old 08-08-2010, 11:57 AM   #7
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Multi-tap warehouse lights


Haven't been able to find "decorative rocker" switches in 2-pole - will have 2 circuits with 5 400 watt fixtures on each. I understand these are 2 amp fixtures so if I run 2 circuits on 110 v each I can use the 15 amp decorative rocker switches I have.
Other choice would be double pole relays triggered by the single pole rocker switches - I could then use 240V but the relays are an adder to the installation - I have 2 10amp @ 240 DPDT relays triggered by 110V.

I agree a 2 pole swithc would be easiest..stuck with the decorative rockers for cosmetic reasons (plus I have a bunch of them already installed)
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Old 08-08-2010, 12:23 PM   #8
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A decorative rocker switches really THAT important in a garage???

If they are then they ARE available in two-pole if you want to take the effort to find them.
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Old 08-08-2010, 12:25 PM   #9
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This took about three seconds:
Let me Google that for you.
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Old 08-08-2010, 01:18 PM   #10
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Speedy Pete - OK so I'm a dummy - never thought to Google them!
Thanks for finding the switches - I'll return the relays to McMaster Carr now..you know how it is when you're dealing with engineers. I made it way too complicated..
Thanks again!
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Old 08-08-2010, 01:31 PM   #11
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Speedy Pete - OK so I'm a dummy - never thought to Google them!
Thanks for finding the switches - I'll return the relays to McMaster Carr now..you know how it is when you're dealing with engineers. I made it way too complicated..
Ahhhhh....an engineer. You are obviously not a dummy, but that explains it.
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Old 08-08-2010, 09:28 PM   #12
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Multi-tap warehouse lights


Your earlier comment on 120 vs 240 made me think a bit as well - I guess there's no free lunch - 5 400 watt lamps are going to pull 2KW whether its 120 or 240 volts. All I gain is a reduction of line loss (if I use 12 AWG for the feeds for either voltage) which may make me feel better but probably isn't measurable in my monthly power bill. With 20 amp breakers though I need to use 12 gauge conductor even at 240 volts. I'm using 2 circuits for 10 lights just so I can have "1/2" on in my man cave unless I need more light.

Would you use 15 amp double pole breakers & 14 awg for 5 of the 400 watt lights or stick with 20 amp & 12 awg for 5 each on the two circuits?
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Old 08-09-2010, 03:26 PM   #13
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If you going to wired on 240 volt you can use the 2.5mm˛ twinner { 14-2 NM } with 5 400 watt luminaires that will be just fine with that set up but if you going to hook up to 120 volts on 15 amp circuit you are only restricted to 3 luminaries but on 20 amp circuit you can go 4 luminaires that why I mention go with 240 volts so you can have more luminaires on the circuit.

Merci.
Marc
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Old 08-09-2010, 09:29 PM   #14
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Merci Marc. I will use 14-2NM with 240 volts. I also will use single pole switch on one hot & leave common always hot. I will label switch cover (inside) & my fixtures to remind myself of 1 leg always hot..

I also heard today that only US & Canada switch hot on 120, everyone else in the free world switches the common.
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Old 08-09-2010, 09:43 PM   #15
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I also heard today that only US & Canada switch hot on 120, everyone else in the free world switches the common.
Where did you hear this???

I wonder what Marc will have to say about this one.

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