Breaker size

[shwn2405]

What's the highest breaker I can put on this wire coming from the house to my pool heater? It has a 50amp breaker currently. Just wondering, thanks

 

[ajw22]

50 amps.

 

[JamesW]

Are you sure that that is the wire?

That is service line for power distribution.

How is the wire run?

How long is the run?

 

[JamesW]

What's the highest breaker I can put on this wire coming from the house to my pool heater?

What heater do you have?

Why do you want to change the breaker?

 

[JamesW]

Note: Check with a licensed electrician before making any changes.

(G) Overcurrent Protection for Specific Conductor Applications.

Table 240.4(G) "Specific Conductor Applications" allows wire sizing for Air-conditioning and refrigeration equipment circuit conductors based on manufacturer specifications.

For a dedicated line for a heat pump, you go by the manufacturer's specifications for Minimum Circuit Ampacity and the Recommended and Maximum Fuse/Breaker size.

For example, an Ultratemp Heat Pump has a specified Minimum Circuit Ampacity of 43 amps and a recommended Breaker size of 50 amps, but it allows a breaker size up to 70 amps.

The chart gives the actual current used, which is listed as 33 amps.

Using the 75 C rating, the allowable ampacity is 50 amps.

The maximum run distance from the main panel to the subpanel breaker is 150 feet to limit the voltage drop to 3%.

MINIMUM CIRCUIT AMPACITY (MCA) vs MAXIMUM OVERCURRENT PROTECTION (MOCP) - Sparkypedia brought to you by Electrician U

Introduction Oftentimes in the field of electrical construction, we rely on others to provide inform

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Table 240.4(G) Specific Conductor Applications.

 

[JamesW]

Note that the ampacity is based on the wire's temperature rating and the ambient temperature that the wire will be exposed to.

The rating is at a temperature of up to 86 degrees Fahrenheit.

For wires that will be exposed to higher temperatures, you have to derate the wire based on the chart.

For example, at a temperature of 96 to 104 degrees, you derate at 88%, which is 50 x 0.88 = 44 amps.

It looks like your wire is rated to 90°C conductor temperature at 20°C ambient.

So, it is rated to 60 amps at up to 86 degrees.

However, it has to be sized at the 75 degree rating, which is 50 amps.

What is the temperature rating of the lugs on circuit breakers?

Are breakers rated for 90C wire?

Product Line and Environment:
All Circuit Breakers

Resolution:

The wire temperature rating allowed for use in circuit breakers lugs is 75°C.

While it is acceptable to use 90°C wire, that 90°C wire must be sized as if it is 75°C wire.

This is according to the UL standard for circuit breakers, which is summarized as follows:

(1) Breakers rated 125 A or less must be marked for use with 60°C, 60/75°C, or 75°C only wire.

(2) For breakers rated more than 125 A, the proper wire temperature rating is 75°C and the marking is optional.

(3) Wire with a higher temperature rating can be used (e.g. 90°C), but the ampacity of the wire must be based on the wire temperature marked on the breaker.

Therefore, as marked on the breaker, the wire must be sized as 75°C wire.

Even when using 90°C wire, the wire must be sized as if it is 75°C wire.

What is the temperature rating of the lugs on circuit breakers? | Schneider Electric USA

So, your #6 AWG Aluminum wire can be used up to 150 feet at up to 104 degrees Fahrenheit and the maximum breaker is 70 amps assuming a dedicated circuit for an UltraTemp 140 Heat pump.

You need to read the label on your heat pump to see the specified minimum circuit ampacity and the maximum allowable circuit breaker.

 

[JamesW]

What's the highest breaker I can put on this wire coming from the house to my pool heater? It has a 50amp breaker currently.

If your 50 amp breaker is tripping and you want to upsize the breaker to try to prevent tripping, this is not advisable because a 50 amp breaker should be plenty and if it is tripping, it indicates a problem that needs to be diagnosed and fixed rather than trying to fix it by increasing the breaker size.

 

[JamesW]

TERMINATIONS.

Cu-Al Wire – All circuit breakers are marked to identify the type of wire for which they are suitable.

The marking includes the words “Copper” and/or “Aluminum” or an abbreviation.

If the breaker is intended for use with a copper wire only or an aluminum wire only, the marking includes the word “Only.”

A breaker intended for use with No. 10-14 AWG solid wire only is marked “No. 10-14 AWG Solid,” or an equivalent wording.

Small Size Wire – Circuit breakers rated less than 15A that have been found acceptable for use with 16 or 18 AWG , rated 10A and 7A respectively are so marked.

This marking may be included in the marked wire range.

Tightening Torque – All circuit breakers are marked with their rated tightening torque for all terminals intended for field wiring.

This is a nominal value.

If the torque is dependent on wire size, the marking indicates the range of tightening torques for each wire size.

Maximum Wire Size – If the terminals of a circuit breaker will not accept the next larger wire size than required for the breaker rating, the breaker or the terminal is marked to indicate the maximum wire size.

Multiple Conductor Connectors – If the terminals of a circuit breaker are acceptable for use with multiple connections in one hole, and the breaker is intended for this type of use, the breaker is marked to indicate the proper multiple connections.

This is uncommon for breakers—ordinarily, the terminals are suitable for only one wire per hole.

60/75°C Wire – All circuit breakers rated 125 A or less are marked for use with 60° C, 60/75°C or 75°C only wire.

This marking indicates the proper wire size for termination in accordance with Table 310.15(B)(16) or Table 310.16 (2020 Edition) of the NEC .

It is acceptable to use wire with a higher insulation rating if the ampacity is based on the wire temperature rating marked on the breaker.

For breakers rated more than 125 A, the proper wire temperature rating is 75°C and it is optional for the breaker to bear this marking.

Molded Case Circuit Breaker - Marking and Application Guide | UL Solutions Code Authorities

UL Marking and Application Guide for molded case circuit breakers and related hardware.

code-authorities.ul.com

 

[JamesW]

So, the answer depends on the actual use and the conditions.

The maximum breaker might be anywhere from 40 amps to 70 amps.

For example, if the wire is being used at 105 to 113 degrees, you have to derate it at 82%, which comes out to 41 amps, which would require a 40 amp breaker.