How to adapt a 30 amp timer box?

[Bodah]

Heya~

I am going to be building one of these soon but the plans that I found are for the older style three pronged dryer outlet and I need to adapt it for the newer 4 prong outlet...

The plans I am going to be using are here...
http://www.hydroponics.net/learn/grow-light-controller.asp

I'm not sure if I am going to be needing a different relay that will accept the neutral wire, or if I should affix the neutral and the ground to each other where the individual outlets will be grounded within/to the box, as I thought they cross in the panel anyways.

Keep in mind I have a decent amount of electrical knowledge but am NOT an electrician, so if I am out to luch with this, thats why ...

Cheers,
Bod

 

[BigWillyDee]

either plug would work...both will have to have 2 hots (black/red) 1 neutral, and a ground. the relay should stay the same a 240 relay is a 240 relay,,,does that make sense.....

 

[Bodah]

Hey bwg,

I was under the impression that the three pronged cord only had three wires? Two hots and a neutral?

So what you are saying is that its ok to tie the neutral and the ground together inside of the box and ground the receptacles to that?

Tia,
Bod~

 

[PharmaCan]

You can tie the neutrals together and run them straight through the box. (i.e. you don't need to relay the neutrals.) You don't what to tie the neutrals and grounds together. What happens in the panel stays in the panel. In any event, if you are using the four prong plug, you have the wires for two hots, a neutral and a ground. Hook all your neutrals together in the box and hook all your grounds together in the box and affix them to the box as per the instructions you linked.

PC

 

[Bodah]

K that makes a little more sense... The only question I have is the receptacles that I will be using are only going to be three pronged, two hots and a ground, so is it a case of me basically wire nutting the neutral from the feed and calling it good?
Everything else I clearly understand just what to do with the neutral line from the feed... Thanks for the help...

Bod~

 

[Skipload]

you dont need to adapt anything. When the 4 prong enters the box, wire it properly the two hots and the ground. The extra common wire is doing nothing. Cut it at the box.
Its only there to stop people from having to run common and ground together.

 

[PharmaCan]

K that makes a little more sense... The only question I have is the receptacles that I will be using are only going to be three pronged, two hots and a ground, so is it a case of me basically wire nutting the neutral from the feed and calling it good?
Everything else I clearly understand just what to do with the neutral line from the feed... Thanks for the help...

Bod~

Hmmm - Not quite sure why you're paying for copper you don't need (the neutral wire). I guess if the run is short and you're using a pre-fab cord, it's probably cheaper than making your own. Anyway, yes, wire nut the neutral and call it good. Don't just cut the wire off and leave it exposed, that's plain stupid.

PC

 

[Bodah]

Thanks guys, thats all I really needed to know. I'd rather ask questions than start a fire, its that simple. Basically if the neutral wire isn't going to be needed then I will use whatever is cheaper, either buy a pre fabbed cord with the neutral and cap it in the box or make my own and just use 10/3. I only need about 4 feet from the dryer receptacle to the box so there won't be that much wasted copper, that stuff ain't cheap ...
Just for curiosity's sake, if in the future I wanted to say move the relay to a different area, how far would I be able to run it safely from the dryer receptacle/panel using 10/3?

Another quick question, using 14/3 for the receptacles how long can I safely make these lines? I was hoping to make them ten feet each, and thinking that anything shy of 15-16 feet would be safe? Thanks again for the help~

Cheers,
Bod

 

[BigWillyDee]

i guess i got here a little late, but yeah make sure to cap the neutral.. goodluck and be careful

 

[Bodah]

Bump~...

 

[VenturaHwy]

or..... you can just buy a 40 amp 240 volt timer (double pole) and save all the hassle.... intermatic - they are used for water heaters or whatever.... add 4 receptacles and you got it...

Are your lights 120 or 240 volts? How many amps each light? Total # or lights?

 

[VenturaHwy]

http://www.electricsuppliesonline.com/int12040tisw.html
Intermatic T104 208-277Volt 40-amp Timer Switch-Double Pole / Single Throw

 

[blubullett]

I would lug the neutral in with the ground. They connect to the same place in the pannel so connecting them downstream wont hurt them, it will actually make the wire run cooler. You might want to look into getting a ground buss, (screws to the box and has a bunch of holes for wires to lug into) It makes the grounds a little better and easier to work on then a bunch of crimp connectors on a stud. You should be fine with 14-3 but 12-3 would be a little safer considering your overcurrent protection is 30 amps (breaker controling the dryer circut).

 

[PharmaCan]

I would lug the neutral in with the ground. They connect to the same place in the pannel so connecting them downstream wont hurt them, it will actually make the wire run cooler. You might want to look into getting a ground buss, (screws to the box and has a bunch of holes for wires to lug into) It makes the grounds a little better and easier to work on then a bunch of crimp connectors on a stud. You should be fine with 14-3 but 12-3 would be a little safer considering your overcurrent protection is 30 amps (breaker controling the dryer circut).

This just plain silly. Think about it, you have a neutral that is unused and a ground that is only going to be used in the event of a short. WTF is there to run cooler??? And if there were a short, why on earth would you want to run that power into your neutral system??? Jeez...

PC

 

[blubullett]

This just plain silly. Think about it, you have a neutral that is unused and a ground that is only going to be used in the event of a short. WTF is there to run cooler??? And if there were a short, why on earth would you want to run that power into your neutral system??? Jeez...

PC

Wire heats up according to the ammount of current running through it. If you have a larger wire it will support more current before overheating. If you look in your pannel you will see that all of the grounds and neutrals lug into the same bussing. From the power company you are fed 2 hots and a neutral. The ground is supplied by the homeowner through a groundrod, which is lugged to the same bussing that the power companys neutral is wired to. Dont talk unless you have something constructive to say or at least know what your talking about.

 

[headfortrinity]

I built one of these last year. It works great, I cut costs and power drop by wiring the ballast cable directly to the mag switch.
Extending the cable is an equation that is a little over my stoned head atm (Ive got a book on it somewhere) I think that you shouldn't have a problem with 15 foot cables but the longer the cable and the more connectors the power has to pass thru the greater the resistance (power drop) If possible run yourself a new 10 guage wire off the main box on it's own breaker and direct wire into the switch, that is how I did mine. and dont hook up the neutral.

 

[BeeBee]

14/3 cord length

14/3 cord length

In regard to how long you can make the cord for each 14/3 receptacle:
Each receptacle powers one 1000 watt (or less) light at 240v. That is under 5 amps. You could make those cords 100 feet long with no problems! That would be a 1% voltage drop (3% is tolerable). Here is the calculator (scroll to the bottom of the page):

http://www.powerstream.com/Wire_Size.htm

In regard to whether to tie the white to the ground wire:

It is ok to do that at both ends, but there is no reason to do it. The ground wire in a 240 circuit carries no current (unless there is a leak in the circuit). So it doesn't need to be as large as the red and the black (or the white)--making it larger by tying them in parallel is a waste of time. Just cut and cap with a wire nut.

I often use relays in this way. It allows you to use any timer of choice, and to place the timer in a convenient location. You can make the power path as short as possible (particularly for the heavy appliance cord, which carries 20 amps), without compromising the ease-of-use of the timer.

 

[PharmaCan]

Wire heats up according to the ammount of current running through it. If you have a larger wire it will support more current before overheating. If you look in your pannel you will see that all of the grounds and neutrals lug into the same bussing. From the power company you are fed 2 hots and a neutral. The ground is supplied by the homeowner through a groundrod, which is lugged to the same bussing that the power companys neutral is wired to. Dont talk unless you have something constructive to say or at least know what your talking about.

Check back after you've wired a few thousand houses and know wtf you're talking about.

1) Neutrals and grounds use seperate bus bars in the main panel and those bars are then bonded together. You don't intermingle the grounds and neutrals elsewhere in the circuits. As a matter of note, in sub-panels the grounds and neutrals are isolated from each other.

2) What current do you think is running through the grounds/neutrals that needs to run cooler? The current flow is in the hot wires, not the neutrals/grounds.

PC

 

[blubullett]

Check back after you've wired a few thousand houses and know wtf you're talking about.

1) Neutrals and grounds use seperate bus bars in the main panel and those bars are then bonded together. You don't intermingle the grounds and neutrals elsewhere in the circuits. As a matter of note, in sub-panels the grounds and neutrals are isolated from each other.

2) What current do you think is running through the grounds/neutrals that needs to run cooler? The current flow is in the hot wires, not the neutrals/grounds.

PC

I have wired a few thousand homes. And now I do service work so i fix what you miswired twenty years ago. Tons of pannels have single bars for the grounds and neutrals. Current flows through the hot and back on the neutral. That is why if you are using a 14-3 for two circuts you have to put black on a phase and red on b phase. If you put them on the same phase you will burn up the neutral. When was the last time you were certified? Sounds like you forgot some of your schooling. Im sure you could teach me somethig but I could help you out too. Have a beer on me :friends:

 

[PharmaCan]

I have wired a few thousand homes. And now I do service work so i fix what you miswired twenty years ago. Tons of pannels have single bars for the grounds and neutrals. Current flows through the hot and back on the neutral.

Your claims of experience are belied by your immature reaction to being told you are wrong and by your use of, "Tons of pannels have single bars for the grounds and neutrals." as a justification for doing it that way. I've read some of your posts about electrical questions and, for the most part, you have been on the right track. As it happens here, you are wrong. The safety ground is just that, a dedicated ground wire to safely conduct any errant electricity to ground. If you hook a neutral to your ground, you could charge the ground wires and energize any metallic object that was grounded. Although the amount of electricity in the neutral system is negligible, you don't want to get even a little shock if you should happen to touch a metallic appliance while grounded. Since neutrals also go to ground they are, in essence, a ground also. But they are part of an electrical circuit and you don't want them charged, which could happen in the event of a direct short and intermingled grounds and neutrals. Electricity will take the easiest route to ground. When neutral and ground bus bars are bonded together in the panel, they are hooked up to a large wire that goes directly to ground. There is a difference between bonding those busses together in the panel and intermingling the grounds/neutrals elsewhere in the circuitry.

BTW - Try putting grounds and neutrals together on the same bus bar here in California, and you'd better be ready for the electrical inspection equivalent of a proctoscope exam. ...and after the inspector left you with an arm's length list of corrections, you'd get laughed off the job by any Sparky in the vicinity.

PC