Main Beam of a Residential House

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bencelest said:
In other words, do I need to install another 100 amp breaker at the main panel to protect the feed wire to the 100 amp sub panel if there is already a 100 amp breaker factory installed on the sub panel.
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Yes. It's the main breaker in the sub-panel that is not required, but is permissable. If this sub-panel were in a separate structure, then both would be required.
To me I am confused now because before, all I need was a breaker at the main panel to protect the sub panel, now there is already a breaker for the sub panel when I bought it to serve as main breaker.
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The breaker in the main panel, which supplies the sub-panel conductors (the feeder), is there to protect the feeder's conductors, not the panel itself. However, the sub-panel must be rated at least as high as the breaker-feeder combination.
Do I need another breaker at the main installed the same rating as the breaker as the sub main?
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No, the breaker at the main panel must be sized to protect the feeder it supplies. It must be the "weakest link" in the pathway from the main panel to the sub-panel's terminals.
I am not familiar with the 2005 NEC book yet and I am still studying it.
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Make sure that's the version of NEC your locality is using.
 
Greg, Dan and Larry, I thank you so much for your clear understanding of the subject.
And Dan, you have a very good sense of humor.
And I had a pre rough-in inspection 2 days ago. I was not ready but the HO had not canceled the electrical . And the inspector said I did really good because I only had 3 violations considering the house is 4,200 sq feet area. And they were minors like no smoke detector at the central location and forgot to put an outlet in the bedroom, etc....very minor. But again, it is not the rough-in inspection yet.
Thanks to this forum, I am doing real fine.
 
Thanks a lot guys for all the help I got. The rough-in inspection went very well. The only thing the bldg inspector said was to bond the hot water heater to the main panel and after that he signed me off.

But I have another question.
The HO wants to install nu-heat to many various rooms in the house. I know that they must be dedicated and on GFCI circuits. But I am getting a cross information between the (probable) dealer/installer and an electrician I talk to.
The installer says that I had to install the GFCI in the panel and I use a 15 amp ckt but an electrician I talked (after I installed the wires)to when I was getting some parts at ED he said that I could use a 20 amp circuit with regular CB on the panel because as he said the nu-heat has a built-in GFCI in the thermostat already.
I already run a 14/3 to various parts of the house but my question is:
Who do I follow? The installer or the electrician?
 
Nuheat has a gfi built into the controller. I hook these up all the time.
 
acrwc10 said:
Nuheat has a gfi built into the controller. I hook these up all the time.
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Agreed. We put these on 20 amp circuits per company standards, anything that heats (even a 1 bulb heat lamp) gets at least a 20 amp circuit to itself.
 
So the installer/dealer was not telling me the whole truth? Can he be trusted in the future?
He also said it costs about $11 per square foot just the heat mat only . Thermostat and contactors are extra and quiet expensive. Over $50. He said I need a dedicated and GFI circuit breaker at the load center not counting the built in GFI at the controller for every 100 square feet or 10 x 10 sq feet area. That's why I set up 6 circuits and 6 separate GFI breakers for the nuheat alone.
Please reply as soon as possibe because tomorrow the HO will call this installer to start.
 
I don't think he fully understands what it needs. The guys that install thim are tile setters not electricians. I would run a deticated circuit to each on a normal breaker. They do need a conduit from the box to the floor for the wires that are coming up from the heat mat. Each mat will have a tag on it saying how many watts it uses.
 
How many square feet? He should be able to tell you how many watts the mat will be, and you can decide wether to use 120 or 240 volts. (before you order the mat)
 
Wire size for Air Handler

Wire size for Air Handler

Is it code compliant if I wire the air handler with # 14 romex when the nameplate rating FLA of 8 amps? It is dedicated circuit and a plug in cord-connected equipment.
I don't have the Instruction manual and I can only depend on the nameplate label. It is located about 100 feet from the main breaker.
According to 440.6(A)Hermitic Refrigerant Motor-Compressor.
...the rated-load current marked on the nameplate of the equipment in which the the motor-compressor is employed shall be used in determining the rating or ampacity of the disconnecting means, the branch circuit conductors.....

and according to 440.32 Single Motor-Compressor
Branch-circuit conductors supplying a single motor-compressor shall have an ampacity not less than 125% of either the motor-compressor rated load current or the branch-circuit section current....
 
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Wire size for Air Handler

Wire size for Air Handler

Is it code compliant if I wire the air handler with # 14 romex when the nameplate rating FLA of 8 amps? It is dedicated circuit and a plug in cord-connected equipment.
I don't have the Instruction manual and I can only depend on the nameplate label. It is located about 100 feet from the main breaker.
According to 440.6(A)Hermitic Refrigerant Motor-Compressor.
...the rated-load current marked on the nameplate of the equipment in which the motor-compressor is employed shall be used in determining the rating or ampacity of the disconnecting means, the branch circuit conductors.....

and according to 440.32 Single Motor-Compressor
Branch-circuit conductors suppplying a single motor-compressor shall have an ampacity not less than 125% of either the motor-compressor rated load current or the branch-circuit seection current....
 
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Is there anybody out there who has an opinion?
It means so much to me! Wether I did wrong or not wether I can confront the HO who is delaying my paycheck.
 
Is it code compliant if I wire the air handler with # 14 romex when the nameplate rating FLA of 8 amps? It is dedicated circuit and a plug in cord-connected equipment.
Click to expand...

If it is plug and cord connected equipment you are probably talking about a room air conditioner and need to look at Part VII of Article 440.

If this is the case then look at 440.62 (A)&(B)

440.62 (B) Where No other Loads are Supplied. The total marked rating of a cord and attachment plug connected room air-conditioner shall not exceed 80 percent of the rating of a branch circuit where no other loads are supplied.

So a receptacle circuit that is wired in #14 NM cable for a room air conditioner is rated at 15 amps and the FLA is 8 amps then you are OK according to 440.62(B)

Chris
 
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