Voltage drop

[Mike Honcho]

couldnt find anything using search function.....

at what distance does voltage drop become an issue for 6 gauge wire on a 60 amp circuit come into play? thanks

 

[pattenp]

At a full load of 60A you will start having a VD over 3% @ about 120ft. At 200ft it will be about 5%. In reality you would be okay up to 150ft if not fully loading the circuit to 60A.

 

[alfredeneuman]

It all depends on the voltage of the circuit, the material used for the conductor, and whether it's a single phase circuit, or a 3Ø circuit

Here's an online VD calculator.
http://www.southwire.com/support/voltage-drop-calculator.htm

 

[wyliesdiesels]

Theres too many variables to be able to use someone else's VD calcs unless everything is the same.

 

[justsam]

Remember these drops as PattenP states are at FULL load of 60 Amps, at which point your feed breaker is probable ready to trip.

Unless you are running HVAC, welder, large compressor, etc. ALL at the same time it is hard for me to see what would be the full 60 Amps.

 

[Highbeam]

Remember these drops as PattenP states are at FULL load of 60 Amps, at which point your feed breaker is probable ready to trip.

Unless you are running HVAC, welder, large compressor, etc. ALL at the same time it is hard for me to see what would be the full 60 Amps.

I think it is safe to assume the OP has 6 gauge copper.

I too have 6 gauge copper on a 60 amp breaker feeding 150 feet or so to a subpanel. Of course, then you also have voltage drop from the sub panel to the point of use to consider.

I worry I'll run into problems since I plan on an electric boiler, lights, and decent sized air compressor.

 

[Stuart in MN]

The Southwire voltage drop calculator in the link above works pretty well, I use it all the time. As mentioned by others, use the actual load for calculations - it will probably be quite a bit less than the 60 amp capacity of the breaker.

 

[Mike Honcho]

Thanks guys. Yes it is copper, about 75-80 foot run.

 

[600SL]

I use this sight.

http://www.paigewire.com/pumpWireCalc.aspx

 

[600SL]

My question on voltage drop is how the amount of connectors in between effects it. For example 12 duplex receptacles daisy chained together over 100'

 

[rockwithjason]

the effect is negilagable when properly terminated.

 

[Aceman]

the effect is negilagable when properly terminated.

You have to remember some posters overanalyze everything....

 

[Mike Honcho]

I use this sight.

http://www.paigewire.com/pumpWireCalc.aspx

thats where i get confused, at 80 feet one way its calling for 4 ga. or is that only if its a continuous 60 amp load?

 

[600SL]

You have to remember some posters overanalyze everything....

Sorry I'm an Aerospace Engineer. But that's what makes flying safe.

 

[rockwithjason]

thats where i get confused, at 80 feet one way its calling for 4 ga. or is that only if its a continuous 60 amp load?

Would anything piss you off more than spending all of that time and money and not having 60a at full voltage when you need it? Thats why i always use full load calculatulations

 

[rockwithjason]

No worries

 

[Mike Honcho]

Thanks for the help guys.

 

[wyliesdiesels]

I use this sight.

http://www.paigewire.com/pumpWireCalc.aspx

I do the math on a calculator:

2 x 12.9(for CU; 21.2 for AL)x distance x amps / 7.2(3% of 240v) or the cir mils of the wire youre using.

If using 7.2, answer will be size of wire required in cir mils at specified voltage drop.

If using cir mils, answer will be amount of volts dropped, then divide by 240 to get percentage of drop...

thats where i get confused, at 80 feet one way its calling for 4 ga. or is that only if its a continuous 60 amp load?

I got just over 28,000 cir mils which is slightly bigger than #6, so next size is #4

 

[Mike Honcho]

At a full load of 60A you will start having a VD over 3% @ about 120ft. At 200ft it will be about 5%. In reality you would be okay up to 150ft if not fully loading the circuit to 60A.

I do the math on a calculator:

2 x 12.9(for CU; 21.2 for AL)x distance x amps / 7.2(3% of 240v) or the cir mils of the wire youre using.

If using 7.2, answer will be size of wire required in cir mils at specified voltage drop.

If using cir mils, answer will be amount of volts dropped, then divide by 240 to get percentage of drop...



I got just over 28,000 cir mils which is slightly bigger than #6, so next size is #4

I'm not about to argue with either one of you, but i dont understand how these are so far apart. I'm sure its not something that can be explained in detail in a forum, but if i can get the cliff notes. Thanks.

 

[pattenp]

I'm not about to argue with either one of you, but i dont understand how these are so far apart. I'm sure its not something that can be explained in detail in a forum, but if i can get the cliff notes. Thanks.

wylies is giving you a precise wire size at no more than 3% voltage drop at a set distance for a given voltage at a known load. I was giving you a broad range with slightly more than 3% up to 5% VD. The way you asked the question doesn't lend itself to a precise answer. If you know the anticipated continuous and non-continuous loads and the exact distance then the wire size needed can be calculated.

 

[sberry]

This is something I eluded to in the 60A thread. Because all this is usually highly speculative it lends itself to some generalization or rule of thumb calculation.

 

[Mike Honcho]

wylies is giving you a precise wire size at no more than 3% voltage drop at a set distance for a given voltage at a known load. I was giving you a broad range with slightly more than 3% up to 5% VD. The way you asked the question doesn't lend itself to a precise answer. If you know the anticipated continuous and non-continuous loads and the exact distance then the wire size needed can be calculated.

that makes sense. I don't see me hitting 60 amps continuous. I have 1 inch conduit that was installed by the previous homeowner, so right now 6 gauge is what I will have to use. I eek check voltage after install, and if need be drop to a 50 amp breaker.

 

[pattenp]

If your run is only 80ft with #6 copper, then you're good to go with a 60A breaker. Voltage drop will be no issue.

 

[Mike Honcho]

If your run is only 80ft with #6 copper, then you're good to go with a 60A breaker. Voltage drop will be no issue.

thanks.