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Old 01-03-2010, 08:56 AM   #16
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Breaker AMP question/opinion?


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Originally Posted by JohnJ0906 View Post
All light fixtures have a very important label on them. The max wattage allowed. If the max is (1) 60 watt bulb, that is what you use when calculating the circuit, not 75 or 100.

My real reason for pointing that out isn't really the load on the circuit, but the fact that I far too often see oversized light bulbs installed in light fixtures, and that is a fire hazard - seriously.

Espically in bathroom recessed cans with an enclosed cover. People wonder why the light goes on and off because they have put a 60watt bulb where a 40 watt is the highest allowed.

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Old 01-03-2010, 08:58 AM   #17
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I'm familiar that 20 AMP is equal to 2400 WATT . At 80% max capability
can support 1920 Volt or 25.6 Light Fixture using 75watt ligth bulbs, but I'm puzzled that the electrician added the 8 receptacles under same breaker.

Alone the 8 receptacles will draw 12 AMP. Thus limiting max wattage for light fixture.
There is NO 80% rule for general use receptacles and lighting in a residential setting. This is a long perpetuated myth.

Also, receptacles do NOT draw anything. Are you referring to what is being plugged in?

I will agree that 21 lights and 8 receptacles is WAY much for any 15 or 20a general use circuit. Thing is though as Mag said, if this is an older home it was pretty typical.

As Scuba said, there is NO code restriction on number of items on a circuit. The 180va rule does not apply and personally I don't feel it should. We just use common sense in figuring circuit layout.
We DO NOT need codes and rules for every single thing we do. Nor do we need to hold the hand of every handyman or diy trying to do things way outside of their experience and knowledge. Some things really do need to be left to the experience of a professional.
If one wants to blanket apply the 180va rule to figuring circuits that is fine too. It's personal choice.
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Old 01-03-2010, 09:01 AM   #18
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Breaker AMP question/opinion?


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Originally Posted by JohnJ0906 View Post
All light fixtures have a very important label on them. The max wattage allowed. If the max is (1) 60 watt bulb, that is what you use when calculating the circuit, not 75 or 100.
Actually even lighting is included in the general load calc. You do not have to calculate each light at it's exact wattage.

See 220.14(J), specifically (3)
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Old 01-03-2010, 09:15 AM   #19
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Originally Posted by Speedy Petey View Post
Actually even lighting is included in the general load calc. You do not have to calculate each light at it's exact wattage.

See 220.14(J), specifically (3)
True, but I use the actuals when calculating a circuit. (When I know the fixtures to be installed)

I will certainly take into account the (21) 40 watt bulbs in that foyer chandelier.
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Old 01-03-2010, 09:16 AM   #20
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True, but I use the actuals when calculating a circuit. (When I know the fixtures to be installed)

I will certainly take into account the (21) 40 watt bulbs in that foyer chandelier.
Oh, I totally understand that. That is the professional experience I was referring to earlier.
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Old 01-03-2010, 11:30 AM   #21
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Breaker AMP question/opinion?


Good points by all
One reason I started learning more about electric (besides the last 2 houses) was to find out exact code & seperate fact from myths

#1 What is required by code
#2 What is required to properly wire a house - to avoid problems
--this is something that electricians know from experience
But some is common sense - not overloading circuits
#3 Preferred wiring methods - commonly followed by electricians

OP's issues:

a) Yes, the single 20a was proberly underkill (not overkill)
Multiple circuits would be much better

b) The load you mention is a Load calc for general use
It is an average calculation to use when determining use & number of circuits you may need
--but if you install a 600w Plasma TV & a high power hoime surround you need to take that into consideration
So I try to plan my loads & possible future loads

c) For lighting loads I load up to 100%, they are not on all the time, not even when the wife is home
I load my Christmas decoration circuits to over 90% sometimes, new wiring
I even loaded one to ~108% once

d) What additional loads ?
In some cases there may be 2 wires under the breaker screw - allowed with some breakers. If you see this it will make it easier to split off some load to a new breaker
Tracing the circuit you also might be able to run a new wire from an outlet box & connect to a new breaker
With an older house I have installed some extra outlets on new breakers to distribuite the load off older overloaded circuits

For my lighting loads I calculate the Load, not the fixture rating
The age of CFL's, LED's & lower power use incandescents has arrived
I have 2 dedicated lighting circuits & 1 older one mixed w/2 outlets
I had a 4th circuit but eliminated it when I realized it only had 400w on it
If someone came in & replaced all the CFL's with older incandescents they could trip a circuit IF they had them all on at once & the ceiling fans

In reality we are lucky if we have more then 500w on at any one time across the 3 circuits

Bottom line - yes it would make sense to have more circuits
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Old 01-03-2010, 02:18 PM   #22
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One of the biggest problems with wiring to minimum code gives you to few options when using equiptment in a home.
If like at my house we use space heating units quite a bit. My wife is always getting 2 on the same circuit then the breakers get their workout. Or she adds the vaccum to the same there goes the breaker getting a workout again.

So its important to try and minimumize this situation.

Just because the code allows something doesnt mean it is good practice.
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Old 01-04-2010, 03:32 AM   #23
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Breaker AMP question/opinion?


Thank you all for the feedback. That helped me to better understand the logic behind minimun code requirements and why an electrician/builder would wire my house the way it is.

Minimun Code Vs Best Practice

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