Length of 30Amp cord?

[mtbbrewer74]

Originally Posted by Bullitt6283

With a really long distance, I might be talking with my electric utility about their cost to place a new service.

I will stick with Direct Buried cable. 80 feet is not that long. I don't want to pay the power company the minimum charge on a meter.

[wags999]

IF you want a 30 and a 20 amp receptacle you need to pull four wires...if you think your going to want or need 50 amp service later, you will need to pull 5 wires...plus your ground.. 80ft is not far, many houses we worked on had longer runs than that, you will lose less than 3% voltage at max amps..


For 30 amp 120 line pull two #10 wires, for 20 amp 120 line pull two #12 lines. Can't use a common neutral since the potential amperage is different. Also either use a grounding rod or a ground wire back to the main panel.


Good Luck, you will love your new convenient receptacle to plug into...

[mtbbrewer74]

Originally Posted by wags999

IF you want a 30 and a 20 amp receptacle you need to pull four wires...if you think your going to want or need 50 amp service later, you will need to pull 5 wires...plus your ground.. 80ft is not far, many houses we worked on had longer runs than that, you will lose less than 3% voltage at max amps..


For 30 amp 120 line pull two #10 wires, for 20 amp 120 line pull two #12 lines. Can't use a common neutral since the potential amperage is different. Also either use a grounding rod or a ground wire back to the main panel.


Good Luck, you will love your new convenient receptacle to plug into...

In order to not have more than 3% voltage drop.
When I run the app on 10awg 30amps I get a maximum of 57ft. When I run the app on 12awg 20amps I get a maximum of 50ft.

As far as the amount of wires I need to run it should only be 4. The underground cable has 1 ground, 1 neutral, and 2 hots. These are all 8awg for the 80 foot run. The panel is setup like a sub panel. It has its own recepticals, and breakers. The neutral and ground will tie together in the panel just like the house panel. Each hot will go to it's own breaker.

[flyboy1]

I read the thread from beginning to end and then ran the numbers for a 50amp service at a distance of 100 feet. Using a #8 THHN or THW copper wire will be more than sufficient. You could also upgrade to a #6 and have a 60amp service but that would just be wasting money unless your going to add more to the circuit than your RV.
If and when you reply, please add your calculations with your comments.

[mtbbrewer74]

Originally Posted by flyboy1

I read the thread from beginning to end and then ran the numbers for a 50amp service at a distance of 100 feet. Using a #8 THHN or THW copper wire will be more than sufficient. You could also upgrade to a #6 and have a 60amp service but that would just be wasting money unless your going to add more to the circuit than your RV.
If and when you reply, please add your calculations with your comments.

Where did your calculations come from? Can you show them to me? I am asking because I am only going to need 30Amp at 80ft.

[flyboy1]

Here are my calculations:
120 Volt Single Phase 30 amp circuit
#8 THHN or THW copper wire, 80 foot run
@30amps Voltage drop = 3.00808
%Voltage drop = 2.50673

@20amps Voltage drop = 2.00539
%Voltage drop = 1.67116
The 20amp data is more of a realistic current draw. My RV has a 50amp service and when I've checked it doesn't even come close to drawing that much current unless everything is started simultaneously and how often does that occur. My normal run
current is less than 25amps.


Here are the 50amp numbers as well;
120 volt 3 phase 50amp circuit
#8 THHN or THW, 100 foot run
@50amps Voltage drop = 5.42708
%Voltage drop = 4.52257


@40amps Voltage drop = 4.34166
%Voltage drop = 3.61805

@30amps Voltage drop = 3.25625
%Voltage drop = 2.71354

[mtbbrewer74]

Originally Posted by flyboy1

Here are my calculations:
120 Volt Single Phase 30 amp circuit
#8 THHN or THW copper wire, 80 foot run
@30amps Voltage drop = 3.00808
%Voltage drop = 2.50673

@20amps Voltage drop = 2.00539
%Voltage drop = 1.67116
The 20amp data is more of a realistic current draw. My RV has a 50amp service and when I've checked it doesn't even come close to drawing that much current unless everything is started simultaneously and how often does that occur. My normal run
current is less than 25amps.


Here are the 50amp numbers as well;
120 volt 3 phase 50amp circuit
#8 THHN or THW, 100 foot run
@50amps Voltage drop = 5.42708
%Voltage drop = 4.52257


@40amps Voltage drop = 4.34166
%Voltage drop = 3.61805

@30amps Voltage drop = 3.25625
%Voltage drop = 2.71354

It looks like we are in agreement. 30Amp circuit #8awg for 80ft. That gives me 2.5% voltage drop which is less than 3%.

[Vicr]

If it were me I'd put in a 13.5KV substation, a 10,000 KVA 13.5KV/480v transformer, a 5000a 480v distribution panel, a 1000kva 480/240v delta Y transformer and a 1000a switchboard, run 500mcm 80' in 4" GRC to a 100a sub-panel with a 2 pole 50a, 1p30a and 1p 20a breaker and have 0% voltage drop. Sorry after 35 years in electrical construction these threads sometimes just split hairs. Most common electrical devices are designed to run between 108v to 127 volts safely so a 3% voltage drop isn't really much to worry about unless you are starting out with marginal voltage to begin with.

[2naEagle]

Originally Posted by Vicr

If it were me I'd put in a 13.5KV substation, a 10,000 KVA 13.5KV/480v transformer, a 5000a 480v distribution panel, a 1000kva 480/240v delta Y transformer and a 1000a switchboard, run 500mcm 80' in 4" GRC to a 100a sub-panel with a 2 pole 50a, 1p30a and 1p 20a breaker and have 0% voltage drop. Sorry after 35 years in electrical construction these threads sometimes just split hairs. Most common electrical devices are designed to run between 108v to 127 volts safely so a 3% voltage drop isn't really much to worry about unless you are starting out with marginal voltage to begin with.

Now that would be cool. Then we could all come visit.

[wags999]

Originally Posted by mtbbrewer74

In order to not have more than 3% voltage drop.
When I run the app on 10awg 30amps I get a maximum of 57ft. When I run the app on 12awg 20amps I get a maximum of 50ft.

As far as the amount of wires I need to run it should only be 4. The underground cable has 1 ground, 1 neutral, and 2 hots. These are all 8awg for the 80 foot run. The panel is setup like a sub panel. It has its own recepticals, and breakers. The neutral and ground will tie together in the panel just like the house panel. Each hot will go to it's own breaker.

Best practice is to use a common neutral with common amperage...since you have a 30 and a 20 amp circuit run two neutrals. 80 feet is not a long run, most homes will have runs over 80ft. Two #10, two #12 and a ground will work fine.. But to each their own...

[mtbbrewer74]

Originally Posted by wags999

Best practice is to use a common neutral with common amperage...since you have a 30 and a 20 amp circuit run two neutrals. 80 feet is not a long run, most homes will have runs over 80ft. Two #10, two #12 and a ground will work fine.. But to each their own...

I see your point. Our house has all 20 amp receptacle feeds, but I don't think it ever sees 20 amps. The camper on the other hand will pull 12.5 amps not to mention the Microwave, and electric water heater.

[mtbbrewer74]

Originally Posted by wags999

Best practice is to use a common neutral with common amperage...since you have a 30 and a 20 amp circuit run two neutrals.

I understand your point, but this box is setup like a sub-panel. I feed the hot, neutral, and ground into the panel and it goes through two different breakers to two different receptacles. It should be like feeding any panel one neutral to the neutral buss, and then all the different circuits connect their neutral to the same buss.

[flyboy1]

The real number is 5% or less of the actual load NOT the rated load.
The national electrical code does not specify <3%.

[Vicr]

Originally Posted by flyboy1

The real number is 5% or less of the actual load NOT the rated load.
The national electrical code does not specify <3%.

?
What are you talking about?