Service Cable

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  #1  
Old 02-24-07, 05:31 AM
W
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Service Cable

Can anyone tell me what size and type cable I will need to go from a meter and disconnect, 120 feet to a 100 amp panel. I want to put this underground.
 
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  #2  
Old 02-24-07, 06:32 AM
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#4 copper or #2 aluminum For the two hots and the neurtal
Plus a #6 ground wire (a seperate debate could start on wether or not one is needed. This depends on other details of the installtion.)

Type UF for direct burial or THWN for in conduit.

Supply houses have direct burry cable assys that have all the conductors already twisted together.
 
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Old 02-24-07, 06:48 AM
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I'm assuming this is the service entrance and not a feed to a detached structure.The bare minimum would be #4 copper or #2 al. IMO for 100 amps at 120 feet you will need #3 copper or #1 al rated for direct burial or wet location in conduit such as USE or THWN conductors. This gives you a little bit better voltage drop under 80% or so load. You will also need 4 wires H-H-N-Grd. The service equipment is the disconnect to the panel so the panel is wired as a sub-panel to the service equipment. You will bond at the disconnect to the service neutral as well as your earth ground for the grounding electrode system. The water pipe grounding electrode conductor (if you have metal water pipes) may terminate on the sub-panel ground bar. Your ground (equipment) ran with the feeder can be #8 ( if the disconnect is 100 amps) but I would go with a #6 if you use copper conductors. You will need 2 ground rods at the disconnect if no test is done to prove 25 ohms or less. Ground and neutral must not be bonded at the sub-panel so don't install the green bonding screw or whatever design the panel uses for bonding ground to neutral, keep them isolated from one another. You also need to know the proper bonding hardware at the disconnect if metal conduit is used from meter to disconnect.

As jw says a lot depends on the installation so more details would help.

Roger
 
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Old 02-24-07, 06:54 AM
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http://www.csgnetwork.com/voltagedropcalc.html

#4 copper at 100 load and 120 feet is 3 % VD

Since the panel should never be loaded beyond 80 amps I cannot see a VD issue.
 
  #5  
Old 02-24-07, 07:03 AM
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Would that size wire be good if I were ever to upgrade to a 200 amp service in the future ?
 
  #6  
Old 02-24-07, 07:06 AM
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JW

Yes I agree. This would be fine. However, we don't know the voltage at the meter.

Roger
 
  #7  
Old 02-24-07, 07:12 AM
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No it would not be capable of 200 amps. Assuming no borderline voltage at the meter you would need 2/0 copper or 4/0 al. You would also need a 200 amp rated disconnect.

Roger
 
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Old 02-24-07, 07:17 AM
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It's a long story

This is a cottage that I bought in the Bahamas. The a--hole that built it ran the power from a neighbors service.The poco says now I need to upgrade the neighbors service wires from the pole to his garage [that's where he installed my meter and disconnect ] and the service wires to my cottage are not large enough. They are underground in 1 1/4 inch pvc. I'm not sure of the wire size, but the poco said they're not sufficient. He then ran them to 50 amp breaker box[ not rated for outdoors], so I have to change that too ! Everything he used was 2nd hand. I think you get the picture [email protected]#@! Buyer beware.What can I say, I was blided by the beach ! Shame on me...I now need to know what to ask the Islands electician for. If I seem to not have a clue to him, I will pay severely. The place is full of pirates still...
 
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Old 02-24-07, 07:34 AM
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Whew!

To be honest I'm not even sure if the info we provided above applies to the Bahamas. If they are on the same power configurations and NEC then it should be reasonably accurate but you better check with some local knowledge. Things can vary widely once you get out of the states.

Roger
 
  #10  
Old 02-24-07, 07:40 AM
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Power since 1990

The island I'm on has only had electricity since 1990. As far as asking locally, there are 2 electicians on the island. I just wanted to have a clue what might be the best way to go.
 
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Old 02-24-07, 07:47 AM
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Unless your planning on building on to this cottage I wouldn't think you would need 200 amps.

Roger
 
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Old 02-24-07, 07:55 AM
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Actually, I'm in the process of building a three stall garage and adding a second floor to the cottage. I am going to be living here for 6 to 8 months of the year. I will be adding 2, one and a half ton a/c units. Possibly a small electric clothes dryer.I'll be using a gas stove and hot water heater.
 
  #13  
Old 02-24-07, 09:52 AM
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Are the a/c's going to be window types or central type?

Roger
 
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Old 02-24-07, 11:31 AM
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They will be split system type.The specs say 208-230v/1ph/60hz. Minimum circuit ampacity 8, maximum overcurrent protection 13, max/min volts 253/188, power consumtion cooling 1890 w, heating 1950 w-----Also I wonder if putting in pvc underground could I use 4/4/4cx150 copper seu wire. it says ,insulated 2 #4 ,bare 1#4
 

Last edited by Wired1; 02-24-07 at 01:16 PM. Reason: more info
  #15  
Old 02-24-07, 08:38 PM
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Number 4 copper's only good to 95 amps @ 90 degree C temp. rating. W/out factoring in the voltage drop, you'll need number 3 copper. Number 2 aluminum will get you there as well.
 
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Old 02-26-07, 09:17 AM
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> Number 4 copper's only good to 95 amps

This rating does not apply to dwelling services or feeders. Services are sized according to table 310.15(B)(6) which allows #4 copper or #2 aluminum for a 100A service.

If there are no local codes beyond the NEC, the #4 SEU copper wire is acceptable for your service.
 
  #17  
Old 02-27-07, 06:01 PM
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Good call....have to remember that one.
 
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