Golf Cart Batteries and Inverters

[Sunking]

Minimum size is determined by the size of the Breaker. 8 AWG up to 40 amps, 6 AWG up to 60 amps.

[BigRich]

The breaker is 46A. Which makes sense because 11,000/240 is 46. This chart says number 8 THHN is good to 55 amps. Why does it say that? What am I missing?

[Sunking]

The breaker is 46A. Which makes sense because 11,000/240 is 46. This chart says number 8 THHN is good to 55 amps. Why does it say that? What am I missing?

My bad, 8 AWG is good up to 50 amps and 6 AWG is good up to 65 amps. Going by memory and had to look at NEC Table

Part of what you are missing wire insulation type is one thing and Terminal temperature is another. Just about all equipment made Terminal Temps use 75 degree C. THHN insulation temp is 90 degree which is used for derating purposes when the wire is in a raceway with more than 3 current carrying conductors. If you put enough wires in a conduit a 6 AWG can be derated to 20 amps maximum. So when an engineer has to derate will select a higher temp insulation for more derated capacity than a 75 degree insulation.

So what you missed is the Terminal Temp is 75 degree C and thus you would use ampacities on the 75 degree column of your chart. There you will see 8 AWG is 50 amps, and 6AWG is 65 amps.

[BigRich]

Ah yes. I see now. Thanks. I never looked at it that way. THHN is capable of carrying 55 amps under certain conditions. Is the terminal temp referring to the connection between the wire and the load and the load specifies what it is rated at?

Also since there will be only two conductors, a neutral, and a ground in the extension cord, I assume theres no need to derate it further based on the number of conductors.

This calculator seems to think I need number 6. Im not sure why. http://www.paigewire.com/pumpWireCalc.aspx

The 75 foot run is from the generator to the transfer switch which is next to the panel. Should I be using the distance from the generator to the furthest outlet instead?

[BigRich]

Ive answered my own question about why that website recommended number 6. Its because theyre using the 60 degree column.

[Sunking]

Is the terminal temp referring to the connection between the wire and the load and the load specifies what it is rated at?

Yes sir

Also since there will be only two conductors, a neutral, and a ground in the extension cord, I assume theres no need to derate it further based on the number of conductors.

OK something is not right here. I think you said this is a 240 volt circuit right? That requires 4-wires and 3 carry current. L1, L2, N, G. No need to derate.

This calculator seems to think I need number 6. Im not sure why. http://www.paigewire.com/pumpWireCalc.aspx

The 75 foot run is from the generator to the transfer switch which is next to the panel. Should I be using the distance from the generator to the furthest outlet instead?

That is because it is taking distance and a voltage drop percentage into account. Keep in mind codes are minimum requirements and does not imply it will meet any performance specification. So if you are required to use 8 AWG minimum only means at least an 8 AWG. The load could be 1000 feet, but it would not work, just an electrically safe failure. Bottom line is you are never going to use the full capacity of the generator, you would burn it up if you did.

Drop the distance and percentage out and you will get 8 AWG. If you are going to take voltage drop into account use 5% and say 30 amps. 75 feet is not far at 120 volts.

[BigRich]

My mistake. Line 1, 2, and the neutral are three conductors, not two.

In order to calculate voltage drop, Im thinking you need to calculate it on these different circuits and use the circuit with highest drop

1. the greatest load at 120 volts
2. the greatest load 240 volts
3. the greatest distance with load at 120 volts
4. the greatest distance with load at 240 volts

[BigRich]

I have the transfer switch installed now. Everything works great. Im thinking of adding an amp meter and overload protection for the generator. Does anyone have any suggestions which ones to buy? I was thinking of these

https://www.amazon.com/DROK-100-300V-Digital-Multimeter-Amperage/dp/B00DVH64HW/ref=pd_lpo_sbs_328_img_1?_encoding=UTF8&psc=1&refR ID=N2GQAC6TNXFWXYMTAQRW
https://mall.industry.siemens.com/mall/en/ww/Catalog/Product/?mlfb=3NW7122

[BigRich]

Does anyone have an opinion on time delay fuses vs non? Id like to get non because I want it to blow right away but am worried about it blowing prematurely because of the starting amps on the various motors around the house.

[Mike90250]

Circuit breakers are also available in styles that don't build up heat and trip at wrong time (magnetic). By the time you blow 1 fuse and replace it, you have spent the cost of a circuit breaker (unless you are working with automotive 12V fuses)

[BigRich]

I have a Siemens panel. Can you recommend one thats 45 amps?

[Mike90250]

I have a Siemens panel. Can you recommend one thats 45 amps?

You are going to have to look at what your electrical supplier carries, or what model breaker fits in your panel. I'd thought you were planning a system and didn't have hardware yet. Midnight Solar carries a wide range of breakers, AC & DC

http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=16&productCatName=Breakers