Wire size?

[Greg Fretwell]

Look at 310.16, 12ga is good for 25a. You are citing 240.4(D) (the 20a rule) but that says "Unless specifically permitted in 240.4(E) through (G)". (G) Overcurrent Protection for Specific Conductor Applications. Overcurrent protection for the specific conductors shall be permitted to be provided as referenced in Table 240.4(G).
Article 430 and 440 permit you to use 310.16 for ampacity and you can also use 430.52 table to determine the overcurrent device if the motor has integral overload protection in the motor or starter (250% of FLA)

The point is, if you see a motor load, you can't depend on 15a=14ga, 20a= 12g, 10a= 30a. and the wire size may not really match the breaker in the simplest sense.

[sparksnmore]

Originally Posted by Greg Fretwell

40 amp breaker, 12 ga wire ... any questions?

I have one if I may.
Where do you see 12 ga wire on that tag?

[Speedy Petey]

Originally Posted by sparksnmore

I have one if I may.
Where do you see 12 ga wire on that tag?

Here, I'll quote Greg from the post just before yours:

Originally Posted by Greg Fretwell

Look at 310.16, 12ga is good for 25a. You are citing 240.4(D) (the 20a rule) but that says "Unless specifically permitted in 240.4(E) through (G)".

[Greg Fretwell]

The label is pretty unambiguous about the breaker, Minimum circuit ampacity is the wire size.

[sparksnmore]

Originally Posted by Greg Fretwell

The label is pretty unambiguous about the breaker, Minimum circuit ampacity is the wire size.

I see but it doesn't have to be the minimum

[Marc D. Shunk]

Originally Posted by sparksnmore

I see but it doesn't have to be the minimum

Of course it doesn't have to be, but it may be and it would still be completely safe and completely legal. This would represent an economical and very servicable installation.

[Speedy Petey]

Originally Posted by sparksnmore

I see but it doesn't have to be the minimum

How can you say that.
It says right there: "MINIMUM CIRCUIT AMPACITY".

[Greg Fretwell]

You as a home inspector are not limited to code problems. You should be pointing out design problems that are beyond code requirements like light switches behind doors and other things that will be a pain in the butt for the new owner . Where I have a concern is when you start pointing to perfectly safe and legal things like the wire size to the A/C condenser (that just don't seem right to you) as a safety problem. This implies that you ARE citing code.

[Jeffrey R. Pope]

Originally Posted by Greg Fretwell

Where I have a concern is when you start pointing to perfectly safe and legal things like the wire size to the A/C condenser (that just don't seem right to you) as a safety problem. This implies that you ARE citing code.

Even worse, it implies that we know better than the codes. . .

[sparksnmore]

Originally Posted by Marc D. Shunk

Of course it doesn't have to be, but it may be and it would still be completely safe and completely legal. This would represent an economical and very servicable installation.

Gotcha, thanks Marc, I was thinking he meant it "had to be minimum".... duha.
We always use 10 ga on those but it's good to know we could save a couple of dollars I suppose.

[Greg Fretwell]

This one is a little more straight forward
8ga wire, 50 or 60a breaker

[nbhi]

Joe
So what your post #20 says, Figure 2, in the text below, That a 40amp protective devise with a minimun wire sizes, awg#10, because the total amps are 27.5

The Branch Circuit Requirements
The branch-circuit conductor size requirements for hermetic refrigerant motor-compressors are located in Part D of Article 440. The sizing requirements for the branch-circuit conductors are very similar to those requirements for standard motors. Basically, the branch-circuit conductors are required to be sized at 125 percent of the rated-load current of the single hermetic motor-compressor or 125 percent of the branch-circuit selection current, whichever is less. However, for combination-load equipment having a nameplate as required by Section 440-4(b), the branch-circuit conductors are required to be "not less than the minimum circuit ampacity marked on the" nameplate of the equipment (see Figure 2). See NEC Section 440-35.
The manufacturer has already calculated the conductor size to be based on the total of all of the motor loads in the combination-load equipment times 125 percent. It is not necessary to do these calculations again. For this type of equipment, the installer and the inspector only have to install and verify that the branch-circuit conductors supplying the equipment have an ampacity equal to or greater than the minimum circuit ampacity marked on the nameplate of the equipment.

[jtedesco1]

Originally Posted by nbhi

Joe
So what your post #20 says, Figure 2, in the text below, That a 40amp protective devise with a minimun wire sizes, awg#10, because the total amps are 27.5

The Branch Circuit Requirements
The branch-circuit conductor size requirements for hermetic refrigerant motor-compressors are located in Part D of Article 440. The sizing requirements for the branch-circuit conductors are very similar to those requirements for standard motors. Basically, the branch-circuit conductors are required to be sized at 125 percent of the rated-load current of the single hermetic motor-compressor or 125 percent of the branch-circuit selection current, whichever is less. However, for combination-load equipment having a nameplate as required by Section 440-4(b), the branch-circuit conductors are required to be "not less than the minimum circuit ampacity marked on the" nameplate of the equipment (see Figure 2). See NEC Section 440-35.
The manufacturer has already calculated the conductor size to be based on the total of all of the motor loads in the combination-load equipment times 125 percent. It is not necessary to do these calculations again. For this type of equipment, the installer and the inspector only have to install and verify that the branch-circuit conductors supplying the equipment have an ampacity equal to or greater than the minimum circuit ampacity marked on the nameplate of the equipment.

and ....

The "maximum overcurrent protective device" rating is the other very important number on the data plate. The overcurrent protection device marked on combination-load equipment is marked "maximum" such as "maximum fuse size." This means that specified size cannot be exceeded. The device could be less than that maximum size.

It may seem that the conductors are improperly protected. However it is the combination of the maximum size short-circuit and ground-fault protective device together with the overload protection system of the equipment that is providing the overcurrent protection for all circuit components. If the overload protection is field-installed for a hermetic refrigerant motor-compressor, the overload sizing must be in accordance with Section 440-52 and must not exceed the manufacturer’s values.

In Figure 2, the nameplate indicates the minimum circuit ampacity and the maximum overcurrent device. Based on the nameplate data the conductors are required to be capable of carrying 27.8 amperes. Remember, with combination-load equipment the 125 percent factor is already used by the manufacturer to determine the 27.8-ampere total. A No. 10 THWN copper conductor is an acceptable size for the circuit conductors. The maximum overcurrent protective device marked on the equipment is 40 amperes. It appears as though the No. 10 THWN conductors are improperly protected. This is not true. The 40-ampere fuse or HACR circuit breaker provides the short-circuit and ground-fault protection. The overload protective device limits the normal running current to the proscribed values.

The overcurrent protective device could be a device rated smaller than 40 amperes as long as it can handle the starting and running current of the equipment. These maximum values are often misunderstood to be the only size allowable by the Code, when in fact it is the value that must not be exceeded.

[nbhi]

Joe
So nothing smaller than 10 awg wire, (12 or 14) correct? Thats because of the amp draw of 27.5, right. And the circuit breaker, nothing larger than a 40?

[jtedesco1]

Please contact the IAEI for further clarification, I posted the reference for you, and I agree and do not question the author Michael Johnston.

Here's another route you (we) can take directly to the people who write the rules.

An example:

Question 2. I am very confused on what inspectors of Riverside County, California, are asking for on A/C condensers (breakers size). For example, if the condenser plate reading has a minimum breaker size of 24 amps, and a maximum breaker size of 35 amps, and I install a 30-amp breaker size, am I in the wrong? Inspectors are telling me that I should go to the max on the breaker. Are they correct? I cannot find this section in the NEC 1999. — F. A.

Answer 2. This is not a violation of the Code unless the nameplate of the unit specifies a minimum size fuse or circuit breaker greater than 30 amperes. Section 440.4(B) in the NEC 2002 applies to air-conditioning equipment that contains a hermetic refrigerant motor compressor and other equipment such as a fan motor. The Code does not require manufacturers to list minimum size overcurrent protective device sizes on the nameplate. The nameplate must only indicate the maximum rating of the fuse or circuit breaker.
If the manufacturer elects to specify a minimum size device on the nameplate, NEC 110.3(B) would require the installer to abide by the nameplate information. — Tom Garvey, CMP-11.

You can find additional information in the NECH and at www.bussmann.com