How many appliances should be on one breaker?

[trader_4]

Must be real swell when one trip puts out the lights in the whole house. And real easy to diagnose, find the fault responsible, when everything is on one breaker.

[gfretwell]

I think I would rather believe Schneider Electric (Siemens, C/H etc) about exactly what their breakers will hold. It should also be noted that NEC article 240.4(D) builds in the 80% safety factor on 12 and 14 ga wire when they limit the breakers to 20a and 15a respectively. The wires are actually good for 25a and 20a but since the installer has no control over what the user may plug in, that safety factor is in the breaker selection.

[trader_4]

on a continuous

s-work/view-all

I looked at his reference and all I see that has anything to do with this is this:

"However, 15-amp breakers and fuses can only carry 12 amps?80 perce nt of their rating?on a continuous basis."

I think where that is coming from is that *code* says that a continuous load has to have the 80% rule applied for the *circuit*. It does not say that the 15 amp breaker will trip at 12+ amps.

I think this explains what's going on too:

[DerbyDad03]

Whenever the question of wiring a workshop or garage comes up, I always mention that the lights should be on their own circuit, regardless of how many other circuits you plan to install.

It really sucks to be plunged into darkness when the breaker trips while you are feeding a long board into a table saw or performing a similar operation with some tool.

[trader_4]

on a continuous

s-work/view-all

After looking at all this and thinking about it, I'm still confused. There are breakers rated at 80% and breakers rated at 100%. It looks to me like either only trip above the amperage on the breaker, eg a 20A will only trip at over 20A. My conclusion is the difference is that if the 80% breaker is used in a circuit with a continuous load, per code, it must be derated per the 80% rule, ie a circuit with a 20A, 80% breaker can only have a max continuous load of 16A. But if a 100% rated breaker is put in instead, then the circuit is code compliant to 20A. Is that right? If not, then I'm more confused.

[gfretwell]

At least the bright side is the saw stops. I actually have lights on 2 circuits. The motion lights are on with one of the garage circuits and the overhead lights are on with the GDO, fed from the house.

[gfretwell]

I have never seen an 80% breaker. The continuous duty rule is generally applied to fixed in place equipment on dedicated circuits and really applies to conductor sizing. If there is multiple pieces of equipment you use 125% of the largest one. and add the rest at 100% to get to circuit ampacity. (the size of the conductor).

[trader_4]

:

?on a continuous

kers-work/view-all

See my new post in the other thread you started and read this:

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It looks to me like it's as I speculated above, ie that the common breakers we use everyday are the 80% ones, which means they are subject to the 80/125% rule for continuous loads. Apparently there are 100% rated breakers and panels, in which case you don't have to apply the rule and can go to 100% of the breaker rating even for continuous loads. But they apparently are not common either.

?Exception: Where the assembly, including the overcurrent devices p rotecting the branch circuit(s), is listed for operation at 100 percent of its rating, th e ampere rating of the overcurrent device shall be permitted to be not less than the sum of the continuous load plus the non-continuous load.? Another restriction applying to 100% rated circuit breakers is found in an exception to Section 210-20(a) of the NEC, especially the words: ?Where the a ssembly, including the overcurrent devices protecting the feeder(s), is listed for o peration at

100 percent ...?: ? The minimum enclosure size and ventilation requirements set forth on the circuit breaker are met, or ? The switchboard has been specifically UL tested for 100% operatio n of the circuit breaker

[trader_4]

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operation at

Forgot to add that whether the breaker is 80% or 100% rated does not change the fact that it will carry 100% of the amperage on the breaker, eg a 20A breaker will carry a full 20A either way.

[gfretwell]

Did you see this part Standard Rated Circuit Breakers Circuit breakers must carry 100% rated current in open air at 40 degrees C until maximum temperatures are reached. The circuit breaker cannot trip and the temperature at the customer connection cannot exceed 50 degrees C rise above ambient.

100% breakers mean that they will carry 100% at the ambient temp of the terminals. (typically 75c)

[trader_4]

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I agree with that, never said or implied otherwise. My point is that what I've see, eg Schneider electric, says this:

Both 80% and 100% breakers will carry their full rated load that's on the breaker handle. It's just a temp rating difference, like you say.

But they further say:

If you have a circuit that's a continuous load and you use the common

80% type 20A breaker and panel, then that circuit is only code compliant if the continuous load is 16A max.

If you have a circuit that a continuous load and you use the 100% type breaker and panel, then that circuit is code compliant for a full 20A.

That is what I get out of Schneider and similar. They cite the NEC exception for 100% breakers/panels. And it makes sense, since the

100% breaker and panel are tested and rated to the higher temp.

[James Wilkinson Sword]

On Thu, 12 Jan 2017 15:20:15 -0000, trader_4 wro= te:

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That makes no sense to me at all. What exactly does 80% breaker mean? = How does this breaker behave at the 80% point?

-- =

The children were lined up in the cafeteria of a Catholic elementary sch= ool for lunch. At the head of the table was a large pile of apples. The = nun made a note, and posted on the apple tray: "Take only ONE. god is wa= tching." Moving further along the lunch line, at the other end of the table was a= large pile of chocolate chip cookies. A child had written a note, "Take= all you want. god is watching the apples."

[trader_4]

On Thursday, January 12, 2017 at 11:51:51 AM UTC-5, James Wilkinson Sword w rote:

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How does this breaker behave at the 80% point?

No need to worry, this discussion is way above your pay grade.

[James Wilkinson Sword]

On Thu, 12 Jan 2017 18:52:10 -0000, trader_4 wro= te:

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Or my level of pedantry.

If you can have a breaker rated 80%, 10A, why not just buy one rated 100= %, 8A?

-- =

The easiest way to find something lost around the house is to buy a repl= acement.

[James Wilkinson Sword]

I told you, the cooker, water heater, shower are on their own circuits. The main circuit of 30A 240V = 7kW is enough for everything else like TV, microwave, washing machine, tumble dryer, etc. Houses with two storeys often have two circuits.

[James Wilkinson Sword]

Where did I say lights were on the same circuit?

And since I have proper fuses instead of the namby pamby breakers, I don't get false trips. A brief overload is allowed.

[James Wilkinson Sword]

Being a ring doesn't make any difference to its use. It just means you use 15A wire in a loop instead of 30A in a straight line. Pointless if you ask me, and dangerous if the ring breaks, but it's to save wire or something.

No, but the plug itself on each appliance has a fuse from 1A to 13A depending on the appliance.

[gfretwell]

That is actually not a bad idea.

[James Wilkinson Sword]

It's an obvious idea, don't your plugs have fuses yet? You can plug anything into an outlet, if it's a 13A outlet, your 0.5A table lamp doesn't have its cord protected against fire from a short.

[trader_4]

If it's a decent short, it will greatly exceed the breaker rating and trip instantly. If it's a short just right to consume a lot of the current on the circuit but not trip it, eg a 12A short on a 15A circuit, then you have that potential with all the wiring anyway and we live with it and it does not appear to be a major cause of fires. We also require arc fault breakers on many circuits now, eg those in the living areas.