I HAVE A 6HP 60 GAL WHAT SIZE WIRE DO I NEED IT.S 40 AMPS

#8 wire for a 40 amp breaker is fine for what you have. You could put a 45 in if you wanted to and #8 wire would still be fine.

The size of the wire is determined by the load it needs to safely carry. This can be obtained from the manual or the supplied fuse size. Once you have found this value, multiply it by 1.25. This means a 10 amp radio will be 12.5 amps. A 30 amp radio becomes 37.5 amps. A 60 amp radio becomes 75 amps - and so on. This is REQUIRED to prevent the wire being used at 100% of its capacity, which would cause it to heat up. Enough heat will cause insulation to burn. Insulation comes into play below. Use the chart linked below - and use copper wire.

http://www.cerrowire.com/ampacity-charts

In order to use this chart properly, you need to determine the insulation type. Different types affect ampacities of the conductor. Typical "romex" wire (the stuff in your house) is rated for "60 deg C (140 degrees F)". Specialty wires THW, THWN, USE, XHHW, THHN etc. are rated at "75 deg C (167 deg F)" and / or "90 deg C (194 deg F)" and have a higher ampacity for the same size copper wire than "60 deg C (140 deg F)" wire as a result. If you do not know which insulation type you have, assume the lowest "60 deg C (140 degree F)" type. Look up the amps you calculated above for your particular radio in the "60 deg C (140 deg F)" column, otherwise look it up under the column with specialty insulation types instead. If the CALCULATED amp value is NOT listed, pick the next LARGER value. Follow it back to the LEFT most column to learn the SIZE wire needed with the same insulation as listed in AMP column.

If your radio was 48 amps, it calculated to (48A x 1.25) = 60A. If you don't have the wire, you can go to a store and say you need 20 feet of #4 copper wire with "60 deg C (140deg F)" insulation, -OR - #6 copper with THW, THWN, SE, USE, or XHHN insulation - OR - #6 copper THWN2, THHN, XHHN2 or USE2 insulation.

The values above hold true regardless if in a circuit that is 6 volts or 600 volts. You should increase the wire size (lower #) on DC circuits only if the circuit length is 50 - 100 feet or more. AC circuits can be hundreds or more feet long before increasing the wire size is needed.

I hope this was helpful & good luck. I hope you've got a ham radio license before you transmit with that radio in the 10 meter band.

Look at rating plate on side of unit for Volts, Amps, Watts.
Volts x amps = watts.
If unit is 240Volts, then you need double-pole 240Volt breaker
If unit is 8500 watts at max power, then 8500 watts divided by 240Volts = 35 amps.

What size breaker for 35 amps?
When electricians figure load rating for breakers, they use the 80% rule.
40 amp breaker x 80% = 32 amp safe maximum load for 40 amp breaker. Use 8 gauge wire with 40 amp breaker.
50 amp breaker x 80% = 40 amp safe maximum for 50 amp breaker. I use 6 gauge wire with 50 amp breaker.
60 amp breaker x 80% = 48 amp safe maximum for 60 amp breaker. Again, use 6 gauge wire with 60 amp breaker.

How to connect wires to unit.
First of all, all outdoor HVAC units require power cut off located next to unit.
This lets the mechanic, or service tech turn power off to work on unit, even if the mechanic does not have access to main breaker box.

Next, open unit to see where wires connect.
If unit has wires, then connect both hot wires from 240 breaker to the wires inside unit. Connect bare ground wire to green ground screw.
If unit has terminals. The terminals will be labeled L1 L2. Connect each hot wire from 240Volt breaker to either one of the screw terminals. Then bare ground goes to green ground screw.

Copy following links for basic illustrations connecting wires to terminals, and to breakers, and selecting wire size.
http://waterheatertimer.org/How-to-wire-Tankless-electric-water-heater.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

I would use a # 10 wire size with a 30 amp breaker. The motor should already wired to the pressure switch unless it has a mag starter. If no mag starter incoming power should go to pressure switch not motor. If unit has a mag starter incoming power should go to top of mag starter.

Check the breakers on the unit How many KW--electric heat? Check to see if you have the right wires wired up to the correct breaker cause some units have 40---and ---60 ---amps breakers and your thickest wire could be wired to the 40-amp breakers,, (some 5 KW pullls 19-23 amps respectably some breakers have 7.5 KW heat stips and pulls more and if the wire size can,t cary the amps, then all you have to do is reduce a heat strip.

How to explain this? your new drop in unit will require a 220v circuit capable of a specified amount of amps. Typically 40, 50 or 60. Should be noted in the manual and on the unit itself. If your original oven and cooktop were electric, then each one was probably hooked up to a 220v circuit. The problem is figuring out how many amps were supplied for each. The simplest way is the go to the panel and find the breaker for the old oven and cooktop and read the numbers (or amps) on the on/off switch. If either breaker has a number the same or greater then the drop in unit says it requires, then your all set. If the drop in unit says it requires 52amps and one of the breakers says 60 on it, your fine. If the drop in unit says it requires 44amps and the breakers are 30 or 40, then you got a problem. Usually a breaker is installed that is the maximum amps allowed for the size (thickness) of the wire connected to it. You CANNOT connected a 50a breaker to wire only rated for 40a. Note the size difference of wire connected to a 20a breaker with wire connected to 40a breaker. If the drop in unit requires more amps then the original units used, then a larger wire will need to be ran from the panel to the drop in unit (Not cheap). Now if the original oven used a 30a and the original cooktop used a 30a, then its possible ( 80% of electricians wouldn't do it because of liability problems) to use both wires together to create 60amps, but both wires (actually a total of 6 wires, 2-120v wires and 1 ground wire from each outlet) would need to be in the same outlet box for the drop in unit connection.. I could (and probably should) try to explain more, but I'de probably just confuse you more. GOOD LUCK!

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3 # 6 wires for the power phase wires and neutral, you can get by with a # 8 on the neutral, but that wire carries all the current im-balance so why scrimp, if you need a safety ground wire i.e. 4 wire plug required in some areas you can use a # 8 wire for this, the # 6 wire will carry 60 AMPS/the # 8 wire will carry 40 amps, most stoves use max 40 amps

NO! Use a switch rated higher in amps and equal to or higher in voltage relative to the breaker rating. Use a 40 or 60 amp switch rated a minimum 220 volts.

Ben, you are on the right track. To upgrade the breaker, first look at the main house breaker panel and determine if allowing more current through main breaker will be taxing it too highly (will 20 more amps exceed my main breaker limit...what is the main breaker current trip at?) Then look at the wire size leading away from the 40 amp breaker to outside. If it is 6 gage copper or 4 gage copper-clad aluminum wire, you are ok to upgrade. Any smaller wire size could be unhealthy.