Convert Branch Ckt Into Sub Panel

[euclid43]

Hi,
There's a reason I am asking this question.....

I am remodeling this basement and the main panel (residential) is embedded in brink (recessed) outdoors, creating a raceway would be difficult. So, I was wondering if I could just take the existing range circuit and make a sub panel with it. It would save me time and money in an already low budget installation. I think it will pass inspection because I can derive 3-4 branch circuits from it in order to complete the basement requirements.

BTW, they are going to convert to gas stove, and if you have time to respond further, let me know your thoughts on branch circuit capacity on a 50 amp sub panel.... is it 125% ?

If the customer wasn't going with a gas range, I could still do this short cut and have range circuit installed in new sub pane, and still have capacity for a couple branches, yes?

 

[Dennis Alwon]

Are you planning on a 120V feeder in this panel or does the old range already have 4 wires. Usually the old ranges have 3 wires

 

[kwired]

Hi,
There's a reason I am asking this question.....

I am remodeling this basement and the main panel (residential) is embedded in brink (recessed) outdoors, creating a raceway would be difficult. So, I was wondering if I could just take the existing range circuit and make a sub panel with it. It would save me time and money in an already low budget installation. I think it will pass inspection because I can derive 3-4 branch circuits from it in order to complete the basement requirements.

BTW, they are going to convert to gas stove, and if you have time to respond further, let me know your thoughts on branch circuit capacity on a 50 amp sub panel.... is it 125% ?

If the customer wasn't going with a gas range, I could still do this short cut and have range circuit installed in new sub pane, and still have capacity for a couple branches, yes?

Not a problem as long as the existing range circuit has separate neutral and equipment grounding conductors.

 

[euclid43]

4 wire setup

 

[Dennis Alwon]

Go for it

 

[euclid43]

Not sure what to tell the customer on the capacity issue, but i think it's 125%

 

[suemarkp]

Um, what do you mean 125%? A 50A feeder is good for 50A. If you have continuous loads, then you'll have less usable capacity (40A if everything is continuous as 40A * 125% = 50A). If this is residential, there are rarely continuous loads in a residence. The feeder is good for 50A as calculated by a load calc.

 

[euclid43]

The breakers are not accumulative like some think (i.e. 4-20 amp breakers do not necessitate an 80 amp breaker panel). So, I am wondering what the general rule is for a 50 amp panel....maybe 3-4 20 amp circuits and another 50 amp can come from the newly installed sub panel. If this doesn't make sense, I'll try another day.

 

[Dennis Alwon]

The breakers are not accumulative like some think (i.e. 4-20 amp breakers do not necessitate an 80 amp breaker panel). So, I am wondering what the general rule is for a 50 amp panel....maybe 3-4 20 amp circuits and another 50 amp can come from the newly installed sub panel. If this doesn't make sense, I'll try another day.

There is no general rule you would have to calculate it based on art 220. You can use 3 watts per sq. ft- not sure what the circuits are for.

 

[euclid43]

My question is not about load calc, but whether there can be 4- 20 amp circuits put on a 50 amp panel. If so, how does the industry determine the threshold on breaker quantity on a particular panel (50 amp or 400 amp, etc.)

 

[Sierrasparky]

My question is not about load calc, but whether there can be 4- 20 amp circuits put on a 50 amp panel. If so, how does the industry determine the threshold on breaker quantity on a particular panel (50 amp or 400 amp, etc.)

Load calculations are the usual method, But as a Master electrician you already knew that.

 

[James S.]

Funny, I did almost the exact same thing last week. 50 amp circuit in the garage was re-tasked as a sub panel to feed a 240v metal halide light pole and some 120v lighting on a new covered patio.

 

[euclid43]

My response is now as basic as can be, thanks to some....can there be 42 breaker capacity in a 50 amp subpanel? And.....can I hypothetically put 42 (15 amp) breakers on this 50 amp subpanel?

 

[infinity]

My response is now as basic as can be, thanks to some....can there be 42 breaker capacity in a 50 amp subpanel? And.....can I hypothetically put 42 (15 amp) breakers on this 50 amp subpanel?

The number/size of the circuit breakers is pretty irrelevant as far as the NEC is concerned. A load calculation would determine the minimum size of the feeder for the sub-panel.

 

[euclid43]

ok, so let's say the load calc is:

VA = 2,100 sq ft x 3 VA sq ft
VA = 6,300 VA

I = VA/E
I = 6,300 VA / 120v
I = 52.5 amps

Circuits:
52.5/15A
number of circuits is 4

All this information is definitive, but I am not sure anyone can say that a 50 amp subpanel is sufficient for a 5,000 square foot basement. NEC doesn't address this or prohibit this because I can conceivably put 40 (15 amp) breakers and a range 50 amp on this newly installed subpanel.

 

[kwired]

ok, so let's say the load calc is:

VA = 2,100 sq ft x 3 VA sq ft
VA = 6,300 VA

I = VA/E
I = 6,300 VA / 120v
I = 52.5 amps

Circuits:
52.5/15A
number of circuits is 4

All this information is definitive, but I am not sure anyone can say that a 50 amp subpanel is sufficient for a 5,000 square foot basement. NEC doesn't address this or prohibit this because I can conceivably put 40 (15 amp) breakers and a range 50 amp on this newly installed subpanel.

One installation you could install 42 circuit panel full of 15 and 20 amp branch circuits and possibly throw the 50 amp main at times.
Another installation you could also have a 42 circuit panel full of 15 and 20 amp branch circuits and never trip the main.

It all comes down to what is supplied and what the load demands are like. Calculating with NEC art 220 usually (but not always) gives you higher ampacity than what actual load conditions will be.

Though I can't recall ever supplying a 42 circuit panel by a 50 or 60 amp feeder in a dwelling, I have supplied 24 or maybe even up to 30 circuit panels with a 60 amp supply. If you avoid having kitchens, laundry rooms, and HVAC loads on such a panel you would be surprised at how much of a dwelling you can supply with only a 60 amp feed and never have trouble with overloading the 60 amp overcurrent device.

 

[infinity]

The breakers are not accumulative like some think (i.e. 4-20 amp breakers do not necessitate an 80 amp breaker panel). So, I am wondering what the general rule is for a 50 amp panel....maybe 3-4 20 amp circuits and another 50 amp can come from the newly installed sub panel. If this doesn't make sense, I'll try another day.

Admittedly this is somewhat simplistic but also keep in mind when you have a 1?, 120/240 volt, 50 amp feeder to the panel you're not limited to only 50 amps of load at 120 volts. At 120 volts you could actually have 100 amps of load.

 

[Dennis Alwon]

I have had 2- 40 cir 200 amp panels filled being fed with 200 amps. I sub fed one from the other with 125 amps. The number of circuits does not matter.

I could wire a house and put each receptacle on it's own circuit. Would that change the load? Of course not.

 

[acrwc10]

ok, so let's say the load calc is:

VA = 2,100 sq ft x 3 VA sq ft
VA = 6,300 VA

I = VA/E
I = 6,300 VA / 120v
I = 52.5 amps

Circuits:
52.5/15A
number of circuits is 4

All this information is definitive, but I am not sure anyone can say that a 50 amp subpanel is sufficient for a 5,000 square foot basement. NEC doesn't address this or prohibit this because I can conceivably put 40 (15 amp) breakers and a range 50 amp on this newly installed subpanel.

Adding to your calculation (50Ax240v=12,000va) you need a minimum of 4 15 amp circuits based on 2100sq.ft. basement 2100x3=6,300va you have double what is required. there is no limit to the number of circuits taken out of that feeder. You can put one breaker one outlet if you want and it doesn't change the feeder size, in residential. In commercial you would be required to use 180Va per outlet. That would limit the number of circuits on the feeder.

 

[Sierrasparky]

when you throw that range outlet in the panel that changes things, you must add the 8K if I recall correctly to the load. In that case it won't work.