An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.

Your house is to new to require any odd, expensive breakers. Garden variety
double pole 30 amp breakers run about $15 each


"asco" wrote in message
ups.com...
An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.

Breakers protect the wire...the units motors have internal
protection...electric heat has its own protection

oh yes...Id still change them...just clarifying that breakers dont
really protect equipment....they protect the wire.

got a phone while posting that previous post...blah blah blah...hit
send....

~:

asco wrote:
An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.


No point in changing. The breakers match the wiring as stated earlier.
Reducing the breaker size wont do anything, but cost you money. IMHO.


--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

"dnoyeB" wrote in message
...
asco wrote:
An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.


No point in changing. The breakers match the wiring as stated earlier.
Reducing the breaker size wont do anything, but cost you money. IMHO.


--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes
9:16

Breakers protect the conductor, the equipment and the user.

Ahh, but the rating of the equipment on the nameplate does not match the
rating of the breaker and that seems to be what the inspector is tripping
on. If the appliance is hardwired, you should change the breaker, if it is
plugged in, it's your call as long as the breaker is same or smaller than
the marking on the receptacle (nod to wire gague as well).

If the nameplate says it uses 30A, a larger breaker is appropriate. If the
nameplate says "breaker size" 30A that is much clearer. It may have both
ratings or just the first (consumption) if that is the case, 40A is the
right size.

In reality on an A/C unit, there are probably no faults that will trip a 30A
that wouldn't also trip a 40A breaker. The difference in trip current
probably wouldn't make much of a difference because any such fault would
likely be due to a dead short. (I suppose a frozen compressor might take a
few more seconds to trip it but its toast by then anyway)

Since you had your house inspected, I might guess you are planning to sell.
Fix it, so the buyers inspector does not site the same thing. That should
be reason enough to act. Up to 1 hour labor plus parts.

You wrote:
"An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is it
an expensive thing to change?"
______________________________________
Re;
Assuming you're talking about the compressor power supply breaker, you
should replace them and it's not expensive if you do it yourself. The
breaker size selection is indeed selected to protect the compressor
motor. That's why a maximum breaker ampacity is given on the unit name
plate. Even though the compressor has an internal motor protective (IMP)
winding temperature limiting device. These IMP devices are last resort
current/temperature limiters and tend to operate (open the circuit) at
temperatures well above (100F+) normal operating temperature of the
windings AND they do reclose only to reopen again if the compressor does
not start. They will cycle like this indefinitely if the wrong supply
breaker is installed, intermittently "cooking" the windings and greatly
reducing the life of the insulation on the windings, until either power
is removed or the reason for the stall, such as high head pressure,
resolves itself.

Back to the breaker. You should select the breaker amperage rating to
be less than the nameplate maximum over-current protection and about
twice the compressor running current. My two 2-ton compressors have a
running current (RLA) of 11 amps and have 20A breakers for protection.
Locked rotor current (LRA) is stated to be 61A. The nameplate calls for
max over-current protection to be NO MORE THAN 30 A. You want the
breaker to trip as soon as possible to prevent "cooking" the compressor
motor windings (even though there is an IMP device) to prevent
degradation of the winding insulation that occurs in a long term
fail-to-start situation as in the case of a blown starting capacitor.

If the breaker is sized right, it will activate (open) before the IMP
does on a stall or start failure.

I hope that helps...
Dan Akers

asco wrote:
An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this?

Depends on whether or not you care about your AC unit being protected
from burning up under various fault conditions. See the post by Dan
Akers.

And if so, is
it an expensive thing to change?

No, it's an easy 5 minute DIY job. Don't be surprised if an electrical
contractor wants $75 or $100 to do it though.

"asco" wrote in message
ups.com...
An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.


With this amount of information impossible to tell.

The maximum overcurrent device of an air conditioner needs to be adhered to,
just good sense.
Changing the disconnect at the unit to a fusible pull out is fairly cheap
and easy to do.
Depending on the length of the circuit just changing the breaker to a 30 may
create more problems.

On 22 Feb 2006 15:13:18 -0800, "asco" wrote:

An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.

No recommendation but if you ARE going to change the breaker yourself,
make them discuss safety with you, like turning off ALL the power to
the breaker box, that is, all the power to the house, bfore you start
touching things inside the box.

Remove NOPSAM to email me. Please let
me know if you have posted also.

PipeDown wrote:
"dnoyeB" wrote in message
...

asco wrote:

An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.


No point in changing. The breakers match the wiring as stated earlier.
Reducing the breaker size wont do anything, but cost you money. IMHO.


--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes
9:16


Breakers protect the conductor, the equipment and the user.


Wrong. Panel Breakers and fuses protect wiring. A Components internal
breakers protect its internal components (motors usually have thermal
breakers) GFCI is designed to protect the user.

Ahh, but the rating of the equipment on the nameplate does not match the
rating of the breaker and that seems to be what the inspector is tripping
on. If the appliance is hardwired, you should change the breaker, if it is
plugged in, it's your call as long as the breaker is same or smaller than
the marking on the receptacle (nod to wire gague as well).


hardwiring vs. plug makes no difference.

If the nameplate says it uses 30A, a larger breaker is appropriate. If the
nameplate says "breaker size" 30A that is much clearer. It may have both
ratings or just the first (consumption) if that is the case, 40A is the
right size.


I'm not aware of any nameplate terminology standards!?

In reality on an A/C unit, there are probably no faults that will trip a 30A
that wouldn't also trip a 40A breaker. The difference in trip current
probably wouldn't make much of a difference because any such fault would
likely be due to a dead short. (I suppose a frozen compressor might take a
few more seconds to trip it but its toast by then anyway)


In reality, breakers are designed to protect against resistive shorts;
Hard shorts are easy. I agree that resistive shorts are rare.
Nevertheless, this is what they do.

Since you had your house inspected, I might guess you are planning to sell.
Fix it, so the buyers inspector does not site the same thing. That should
be reason enough to act. Up to 1 hour labor plus parts.



I wouldn't call it a 'fix.'


--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

Dan Akers wrote:
You wrote:
"An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is it
an expensive thing to change?"
______________________________________
Re;
Assuming you're talking about the compressor power supply breaker, you
should replace them and it's not expensive if you do it yourself. The
breaker size selection is indeed selected to protect the compressor
motor. That's why a maximum breaker ampacity is given on the unit name
plate. Even though the compressor has an internal motor protective (IMP)
winding temperature limiting device. These IMP devices are last resort
current/temperature limiters and tend to operate (open the circuit) at
temperatures well above (100F+) normal operating temperature of the
windings AND they do reclose only to reopen again if the compressor does
not start. They will cycle like this indefinitely if the wrong supply
breaker is installed, intermittently "cooking" the windings and greatly
reducing the life of the insulation on the windings, until either power
is removed or the reason for the stall, such as high head pressure,
resolves itself.

Back to the breaker. You should select the breaker amperage rating to
be less than the nameplate maximum over-current protection and about
twice the compressor running current. My two 2-ton compressors have a
running current (RLA) of 11 amps and have 20A breakers for protection.
Locked rotor current (LRA) is stated to be 61A. The nameplate calls for
max over-current protection to be NO MORE THAN 30 A. You want the
breaker to trip as soon as possible to prevent "cooking" the compressor
motor windings (even though there is an IMP device) to prevent
degradation of the winding insulation that occurs in a long term
fail-to-start situation as in the case of a blown starting capacitor.

If the breaker is sized right, it will activate (open) before the IMP
does on a stall or start failure.

I hope that helps...
Dan Akers



The motors internal protection is not backup protection, but its primary
protection as far as the motor engineers are concerned. Motors are
damaged by heat, thats why they have thermal breakers. External
breakers are not sensitive to the thermal conditions at any point in
time, within a motor. The motor itself is adequately protected by its
internal breaker is does not get "cooked." The external breaker is
necessary to protect the external wiring normally.

The assembly internal wiring should be able to handle motor stall
current. But if they are trying to cut costs, they may downsize the
wiring then put the onous on the installer to protect the internal
wiring by using a smaller external breaker.

So if the faceplate specifically calls for a breaker size he better
stick with it. But if it doesen't, he is fine.


--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

Did the OP say what was the wire size? I went back and read, and didn't see
it.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

"dnoyeB" wrote in message
...
asco wrote:
An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.


No point in changing. The breakers match the wiring as stated earlier.
Reducing the breaker size wont do anything, but cost you money. IMHO.


--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

On 22 Feb 2006 15:13:18 -0800, "asco" wrote:

An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

If the wire is #10 copper or better, there's no reason to
change breakers. If it's #12 copper, you should be on
30A breakers. If it's less than #12 copper, you should
run new lines. The breaker doesn't care what the power
draw of the terminal appliance is.

--Goedjn

dnoyeB wrote:


Breakers protect the conductor, the equipment and the user.


Wrong. Panel Breakers and fuses protect wiring. A Components internal
breakers protect its internal components (motors usually have thermal
breakers) GFCI is designed to protect the user.


Under the NEC for motor circuits, like this, the panel fuse/breaker
provides short circuit protection for the wires. Protection for the
motor is provided by an overload device that matches the current and
starting characteristics of the motor - which is a motor starter
'overload unit' or 'thermal protection' in the motor. Fuses/breakers
have to withstand the starting current of the motor, and have widely
spaced ratings (30, 40 Amp), and as a result don't trip on overloads
although as Dan Ackers said they MAY trip on repeated restarts by the
'thermal protector'. In general time delay fuses can be 175% of the
motor running amps. The fuses can be larger than the rating of the
supply wires and protect them from short circuit - overload protection
is provided by the motor overload device. The rules for motors are IMHO
rather arcane and should be applied by soomeone who understands them.
All of this agrees with dnoyeB. However the panel fuse/breaker also
provides some protection for the equipment, and motor starters and other
equipment are likely to have a maximum fuse/breaker size.

Ahh, but the rating of the equipment on the nameplate does not match
the rating of the breaker and that seems to be what the inspector is
tripping on. If the appliance is hardwired, you should change the
breaker, if it is plugged in, it's your call as long as the breaker is
same or smaller than the marking on the receptacle (nod to wire gague
as well).


hardwiring vs. plug makes no difference.


If equipment comes with a cord and plug it would be reasonable to expect
it could be plugged into a matching receptacle. Hardwired equipment has
to follow information on the nameplate (but that is also true for cord
connnected equipment).


If the nameplate says it uses 30A, a larger breaker is appropriate.
If the nameplate says "breaker size" 30A that is much clearer. It may
have both ratings or just the first (consumption) if that is the case,
40A is the right size.


I'm not aware of any nameplate terminology standards!?


Hardwired compressor units for central air are commonly nameplate marked
with "maximum fuse size" or "maximum breaker size". It is a code
violation not to follow these ratings and could void a warranty.
"Maximum fuse size" requires fuses.

In reality on an A/C unit, there are probably no faults that will trip
a 30A that wouldn't also trip a 40A breaker. The difference in trip
current probably wouldn't make much of a difference because any such
fault would likely be due to a dead short. (I suppose a frozen
compressor might take a few more seconds to trip it but its toast by
then anyway)


In reality, breakers are designed to protect against resistive shorts;
Hard shorts are easy. I agree that resistive shorts are rare.
Nevertheless, this is what they do.


But equipment, like motor starters, often have a maximum fuse/breaker
size which protects the equipment from damage.

bud--

dnoyeB wrote:
asco wrote:
An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.


No point in changing. The breakers match the wiring as stated earlier.
Reducing the breaker size wont do anything, but cost you money. IMHO.

What? The unit MOP (Maximum Overcurrent Protection) cannot be
exceeded, period, no exceptions. In a motor circuit the CB provides
the short-circuit and ground-fault protection. The motor overloads are
what protect the wire in a motor/compressor circuit. The wire needs to
be no larger than the MCA (Minimum Circuit Ampacity). For example, on
a condensing unit that has an MCA of 35 amps and an MOP of 60 amps, the
wire size need only be a #8 and the maximum breaker can be up to, but
not exceeding, 60 amps, as permitted by NEC. As you can see, a 60 amp
breaker on a #8 wire is not going to protect against overcurrent.
Again, the compressor overloads are what protect the wire IN THE CASE
of motors and compressors. The only time that the CB provides
short-circuit, ground-fault protection AND overcurrent protection in a
motor/compressor circuit is when it is rated at no more than 125% of
the motor/compressor Full Load Amps.

asco wrote:
An inspection on our home (7years old) recently revealed that both our
air conditioning units have 40 amp circuit breakers instead of 30 amp
(the unit asks for 30 amps). How big of a deal is this? And if so, is
it an expensive thing to change?

Thanks in advance.


In case Bud's post isn't clear enough let me explain. There are two
ampacities listed on the nameplate of a motor/compressor unit's name
plate. One is the circuit selection ampacity. This minimum circuit
ampacity is the minimum the circuits conductors must be rated for in
table 310.16 of the US NEC. Section 240.4 which limits 14, 12, and 10
gage conductors to certain overcurrent protection values reads in part
"240.4 Protection of Conductors.
Conductors, other than flexible cords, flexible cables, and fixture
wires, shall be protected against overcurrent in accordance with their
ampacities specified in 310.15, unless otherwise permitted or required
in 240.4(A) through (G).
(D) Small Conductors. Unless specifically permitted in 240.4(E) through
(G), the overcurrent protection shall not exceed 15 amperes for 14 AWG,
20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes
for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum
after any correction factors for ambient temperature and number of
conductors have been applied.
(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).

Table 240.4(G) Specific Conductor Applications
Conductor Article Section
Air-conditioning and refrigeration 440,
equipment circuit conductors Parts III, VI

Capacitor circuit conductors 460 460.8(B)and 460.25(A)–(D)
Control and instrumentation 727 727.9
circuit conductors (Type ITC)

Electric welder circuit conductors 630 630.12 and 630.32
Fire alarm system 760 760.23, 760.24, circuit conductors
760.41, and
Chapter 9, Tables 12(A) and 12(B)
Motor-operated appliance 422, Part II
circuit conductors

Motor and motor-control 430, Parts III,
circuit conductors IV, V, VI, VII

Phase converter supply conductors 455 455.7

Remote-control, signaling, 725 725.23, 725.24,
and power- limited circuit conductors 725.41, and


Chapter 9, Tables
11(A) and 11(B)
Secondary tie conductors 450 450.6"

Notice that the first line of Table 240.4(G) covers Air-conditioning and
refrigeration equipment circuit conductors. The referenced parts of
article 440 provide for the selection of Over Current Protective Devices
(OCPD)for air conditioning equipment. Conductors used to supply such
equipment are sized by the table 310.16 values and not by the size of
the OCPD. The OCPD is sized to allow the compressor to start reliably
even under adverse conditions such as already pressurized refrigerant
gas piping. The overload protection for both the circuit conductors and
the motor itself is provided by overload relays mounted in the motor
itself.

The upshot of all of that is that if the conductors are sized so that
their table 310.16 ampacity equals or exceeds the minimum circuit
ampacity that is on the compressor unit name plate then they are
properly sized. Likewise if the supply circuit's OCPD does not exceed
the maximum circuit over current protective device value, and type if
any, that is shown on the compressor unit name plate it is also properly
sized.

This also means that home inspectors should not attempt to do electrical
inspections but should leave that work to Master Electricians and
certified electrical inspectors.

RANT MODE ON
IT ISN'T JUST COLOR TO COLOR PEOPLE! You cannot do safe, competent, nor
cost effective electrical work without taking the time to actually learn
the craft. IF YOU CANNOT OR WILL NOT TAKE THAT TIME THEN KEEP YOUR
HANDS OUT OF ELECTRICAL EQUIPMENT AND KEEP YOUR "THOUGHTS" ABOUT HOW IT
SHOULD BE DONE TO YOUR SELF! Incompetent advice is a bigger danger than
incompetent work because the bad advise can cause dozens of hazards in
multiple places instead of just one or two in one place. I have plenty
of experience suppressing and reporting fires of electrical origin,
injuries caused by electric shock, and deaths by electrocution. I AND
THE REST OF THE NATIONS FIRE AND RESCUE SERVICE DO NOT NEED OR DESIRE
ANY MORE!
rant mode off.
--
Tom Horne, Firefighter EMT

Well we aren't no thin blue heroes and yet we aren't no blackguards to.
We're just working men and woman most remarkable like you.