running wire from main panel to a backyard light post

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Old 10-18-09, 04:48 PM
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running wire from main panel to a backyard light post

This light post is for my backyard basketball half-court. The light post has two 400W metal halide bulbs. There is a 10/3 insulated water resistant cable extending from the bulbs to the bottom of the post. The cable has 3 conductors inside: black, white and green. I'm told by the people who installed the basketball court & light post that I need to use 220/240V for the light bulbs. I need your help to complete the electrical hook-up for the light post.

What I intend to do is:
-add a double 30am (20am ?) circuit breaker (GFCI) in the main panel (220/240V circuit);

-running wire from the main panel inside the house to a water proof junction box mount on the wall outside of the house (about 8 feet);

-runing UL cable through a conduit from the junction box to a switch in the garage wall (about 8 feet) so that the bulbs on the post can be controlled from this switch in the garage; and

-running an underground 10/3 (10/4?) insulated, water-resistant cable (buried 18 ft deep, probably inside a PVC conduit if Code requires) from the junction box to the bottom of the light post (about 75 feet). I'm not sure how I can make the connections between a 10/4 cable (2 hot, 1 neutral, 1 ground - required by 220/240V) to a 10/3 cable (1 hot, 1 neutral, 1 ground) in the light post (please advise).

Please check and let me know what I intend to do is proper/OK. IF you need more information , please post. Thanks so much in advance.
 
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Old 10-18-09, 05:00 PM
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Two 400 watt lights would be 800watts at 240v or 3.3 amps. You can use 14-2 UF able on a 15 amp 2 pole breaker. You should not use cable in conduit except short sections above ground to protect it. If you use conduit yuo would use two black #14 THWN conductors and one #14 bare or green THWN conductor.


Cable is usually buried at 2' conduit at 18". Always follow the manufacturers recommendations. Check the name plate to be sure they are 240v. If you use UF cable the white must be re marked black, red or any color but green or white. You can use marking tape, marker pe, or paint,
 
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Old 10-18-09, 05:22 PM
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Ray.,

Small correction to you,

You have to add both lamp and ballast to get the correct total wattage for the luminaire and the correct answer is 2.0 amp per luminaire so total is 4.0 amp

To OP.,

You only need 15 amp double pole breaker and no you do not need the GFCI unless you are near the pool area

from the garage to the luminaire post you can use the 12-2 UF but make sure you remarked the white conductor so you know this is a 240 volts useage.

you can bury the cable 18 inches deep { my area do reqired to be at least 24 inches } or run in the conduit and use the THHN/THWN for two reason why one for power supply for the luminaires and have second circuit for the outdoor receptale that location put a GFCI receptle there so you have standard 120 volt power for your portable radio or whatever you suit for it.

And make sure you double check the ballast connection to verifed that is on 240 volts just trust me I know majorty of 400 watts luminaire are wired for 277 volts by default but there is other voltage connection can be done if need to be.

Merci,Marc
 
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Old 10-18-09, 06:10 PM
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Marc, just for my information did you go with #12 because of stating current or distance or both?
 
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Old 10-18-09, 06:38 PM
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Ray .,

400 W MH the running current is higher than starting current and I did checked with the distance and it is withen the voltage drop range for 240 volt circuit.{ most 400 w MH ballast are useally CWA but once a while you will snag a RX reactor they are worst the starting current is higher }

And the distance of the OP's luminaire set up is about right there so it is not a issue on 240 volt but if that was conferated for 120 volts .,, forget it will need #10 for sure

Merci.

Marc
 
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Old 10-18-09, 10:07 PM
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Thanks Ray & Marc for your quick replies:

So I will use:
- a 15 amp double breaker in the main panel;
- THHN/THWN cable(s) in a PVC conduit (18 inch deep) from the outside junction box to the light post so I will have a 240V power supply for the two 400W bulbs and a standard 120v GFCI receptacle for portable radio, etc.
- a length of about 8 feet of cable(s) will go from the 15 amp double breaker in the inside main panel to the water proof outside junction box;
- a length of about 5 feet of cable will go from the junction box to a switch that controls the 2 light post bulbs.

Please tell me the size, type and number of cable(s) that I need to use (1) from the double breaker to the junction box; (2) from the junction box to the switch; (3) from the junction box to the GFCI receptacle near the light post; and (4) from the junction box to the 10/3 cable connected to the bulbs.and how the conductors.
And please tell me how the wires/conductors of the cables are connected at the double breaker, at the junction box, at the switch, at the GFCI receptacle and at the bottom of the light post (10/3 cable from the bulbs).

Thank you very much in advance for your help/time.
 
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Old 10-19-09, 02:29 AM
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so I will have a 240V power supply for the two 400W bulbs and a standard 120v GFCI receptacle for portable radio, etc.
The receptacle can not be on the same breaker but the wiring can run in the same conduit. The receptacle would be on a single pole 20a breaker. Use #10. The receptacle or breaker should be GFCI. You can use a single #12 ground wire for both circuits if you terminate both in the same box and then split the ground.
 
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Old 10-19-09, 12:37 PM
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Please let me know if the below circuit is proper and please suggest if it can be improved. Thanks again.

new circuit for basketball court lights picture by hcdang - Photobucket
 
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Old 10-19-09, 01:41 PM
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I just learned something new reading this post: http://forum.doityourself.com/electr...-off-mwbc.html

You may be able to do it with out adding a second circuit which would save on wire cost. You would need to run two black and one white number 10 and a #12 green or bare. Wait for a pro to come along and recommend how to proceed.
 
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Old 10-19-09, 05:26 PM
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There are couple items that need to be address in here .,

The switch to control the HID luminaire if you are on 240 volts you must use the double pole switch I know you can use single pole switch but for safety point of view it is not safe at all in case someone working on the luminaire for any reason it can get hit due one of the conductor stay alive all the time so double pole switch will elemated the issue what you have there.

Second thing I will not recomened to run MWBC on this set up due the HID and you will need seperated circuit for 120 v 20 amp GFCI

I know you will run the whole thing in conduit it will be easier to get red and black for HID then get Bleu for GFCI receptale I know a bit of big box store will stock a cut off from the bulk reel.

The white conductor is fine you will have no issue.

You have two choice to put the GFCI receptale either on the Garage wall or at the post if at garage wall then you can use the standard receptlae with in use cover box or run stragit to the WP box on the post.

Ray's quote
You may be able to do it with out adding a second circuit which would save on wire cost. You would need to run two black and one white number 10 and a #12 green or bare. Wait for a pro to come along and recommend how to proceed.
Ray look at above comment you will understand why I don't recomend the MWBC on this set up. { due the OP have switch at garage wall if at the pole then yeah it can be done like that }

Merci.
Marc
 
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Old 10-19-09, 05:31 PM
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Missed the switch part. Thanks Marc.
 
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Old 10-19-09, 05:40 PM
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Originally Posted by ray2047 View Post
Missed the switch part. Thanks Marc.
No Problem at all that what we are here for. Beer 4U2


Merci.
Marc
 
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Old 10-19-09, 08:56 PM
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Again, thanks so much Ray & Marc,
I have just revised the circuits based on your advice. Please check the revised image in the link below and let me know if it is proper. Please note the sizes of the wires: #10 THWN wires for the FGCI receptale and #12 THWN wires for the two 400W light bulbs; and #12 bare ground wire shared by the receptacle, light bulbs and double switch.

Revised Circuits for light post picture by hcdang - Photobucket
 
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Old 10-19-09, 09:18 PM
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That look better now and also from the breaker box to the GFCI recetpale you can use #12 THHN/THWN and yes I know pretty good precentage of big box store may have bulk roll that can be cut down to the length you need.

I did relaized that you will run two pairs of cable from breaker box to the HID and outdoor GFCI receptale there is one tip I always do is mark the sheating { coating } with marker so before I get into the box I remark one white conductor with red marker so I know that is legit 240 volts then rest will fall in the place and make sure you make a grounding pigtail you will need it anyway.

But if you want to stay with #10 that fine but keep in your mind it will be more stiffer than #12 will be and becarefull with the room in the junction box it don't take much to get it filled up and also most GFCI recetpales useally take #12 conductor without much issue but some will take #10 also { if backwired that fine but becarefull when you fold it in you may not have much room if you use standard size waterproof box so get deepwell verison if you can.}

also the #10 will cost somehow more than #12 so it is your call for myself if not running anything super hevey at the GFCI reptale the #12 will suit it just fine.

Merci.

Marc
 
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Old 10-19-09, 09:22 PM
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Post deleted. Marc posred as I was writing.
 
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Old 10-19-09, 09:31 PM
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While I am reviewing this thread and this topic and somehow it click on my mind what type of post materal it willbe like wood or steel or fiberglass or Alum post ??

The reason why I did make a blunder due I was reviewing my customer paperwork and when I was reading the pole specfics and all I say oh oh I miss this one so OP please reply to us and how high it is too ?

Merci.

Marc
 
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Old 10-19-09, 09:35 PM
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Thanks for your quick response, Marc.
I will use #12 for the receptacle. I chose #10 as it was mentioned by Ray in one of his posts. I thought #10 was probably required because of the 75-80 feet distance. Of course as you mentioned, #12 would make the job easier & less money too. Thanks again for your help and Ray's help. I really appreciate this website & and the people here.

I'll start the project tomorrow and will report back when I finish it. It will probably take 2 weeks since I have a full time job and I will get a permit and will get a county building inspector's approval for my work.
 
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Old 10-19-09, 09:41 PM
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Originally Posted by french277V View Post
While I am reviewing this thread and this topic and somehow it click on my mind what type of post materal it willbe like wood or steel or fiberglass or Alum post ??

The reason why I did make a blunder due I was reviewing my customer paperwork and when I was reading the pole specfics and all I say oh oh I miss this one so OP please reply to us and how high it is too ?

Merci.

Marc
Marc,
The pole is made of steel and it's about 18-20 feet height. Thanks.
 
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Old 10-19-09, 09:42 PM
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Keep us posted how it come out.



For Metal post or Fiberglass post you will need concrete base so you will need min of 18 inch diamiter otherwise I use 24 inch diam sonotube and go down below frost line typically in my area I go down at least 42 inches.

{ check with your luminaire manufacter to give you the specfics what it need and please follow their instruction very carefully with the pole set up }

I done this pretty often { the last one I done was a parking lot luminaires 18 of them }

Edit:

As soon I got done typing here and you reply so I change my text here to give you a correct info 18-20 is plenty high for 400 watt Metal Halide that will light up pretty nice

Merci.
Marc
 
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Old 10-19-09, 10:01 PM
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Originally Posted by french277V View Post
Keep us posted how it come out.



For Metal post or Fiberglass post you will need concrete base so you will need min of 18 inch diamiter otherwise I use 24 inch diam sonotube and go down below frost line typically in my area I go down at least 42 inches.

{ check with your luminaire manufacter to give you the specfics what it need and please follow their instruction very carefully with the pole set up }

I done this pretty often { the last one I done was a parking lot luminaires 18 of them }

Edit:

As soon I got done typing here and you reply so I change my text here to give you a correct info 18-20 is plenty high for 400 watt Metal Halide that will light up pretty nice

Merci.
Marc
Thank you for your concern, Marc.
The basketball court and light pole including 2 bulbs & an insulated 10/3 cable within the light pole were already installed by professionals (a company that builds all kinds of backyard courts). All that I need to do is run electric power from my house to the bottom of the light pole. The company would do it for me if I agreed to pay them an additional amount of $875. I thought it's too expensive and decided to do it myself with a labor helper to save some money. It means you and Ray save me a bunch of money!
Of course I will post how it comes out & some pictures when I finish. Thank you very much!
 
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Old 10-20-09, 08:32 PM
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Marc or Ray,
Please take a look again at the circuit for the light post (2 hot wires from 15 amp double breaker are connected to 2 non-ground wires from the light post). Is it OK that this circuit has no neutral wire (no wire from the circuit connected to the neutral bar in the main panel). I guess the brown ground wire functions as both neutral and ground in this case. I don't want to burn the bulbs when I turn on the switch. Merci beaucoup!

Revised Circuits for light post picture by hcdang - Photobucket
 
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Old 10-20-09, 09:02 PM
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Mimi.,

The cable from the 240 volt luminaire I know they useally come in black and white and green so what you will do is remark the white to red and you are good to go.

speaking of ground the 240 volt luminaires only need ground for safety issue you do not need netural at all so you will not worry about with the luminaires.

So with luminaire cord when you see the green conductor just wirenut together with bare or green conductor and you are good to go.

I will give you a quick run down with how the Metal Halide performace due there is two verison of this type;

Common probe start AKA old school type ;

It will take up to 5 min to warm up to full brightenss but when you turn off the switch or power inturpted or serious voltage drop and want to come back on quick it will take up anywhere from 15 min to 45 minutes depending on how cool the weather.

When they are new expect some pinkish colour show up first couple hundred hours burning time that is normal so expect that.

They will last pretty long time typically 16000 to 20000 hours so for your basketball court you will go more than 5 years before you do anything with the bulb.

Now the second type what we call pulse start :

To warm up from cold start it will take anywhere from 3 to 5 min to full brightenss but big diffrence is restrike time it will be much shorter time useally 5 to 10 minuites some case less.

The bulb life on Pulse start useally longer than old probe start verison typically 16000 to 24000 hours and they are little more brighter than old probestart verison depending on which type of MH bulb you use.

I work on them alot so I am very famuair with it.

Oh yeah between the probe start and pulse start they are not interchangeable even thru the socket are the same but starting aids are diffrent so if you have to replace make sure you follow the correct bulb numbers.

Merci.
Marc
 
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Old 10-20-09, 09:52 PM
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Thank you, Marc.
I didn't know any of that. I don't know what type (probe or pulse) I got. It is very interesting and will be very helpful in the future when I need to replace them.
 
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Old 10-26-09, 06:09 PM
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Hi Marc,
I have another question for you.
Cam I use a 20 amp double pole breaker rather than a 15 amp double breaker for the 240V metal halide bulbs? The wires that I use are #12 so I guess they are suitable for 20 amp breaker. I have gone to 5 different stores in my area but they don't carry the 15 amp double pole for my GE main panel which use thin type breakers. Thanks again.

Revised Circuits for light post picture by hcdang - Photobucket
 
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Old 10-26-09, 06:31 PM
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Mimi.,

Sure you can use 20 amp double pole breaker as long the whole circuit is #12 that is not a issue at all.

I kinda suprised that many store don't stock that and I know for sure it is pretty common breaker to find.

Anyway that will work just fine without any issue at all

Merci,
Marc
 
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