How Much Amperage Can a Two Pole 60amp breaker use?

[Mike Myers]

I have a 60 amp two pole breaker that a sub panel runs off, Three 30 amp breakers in the subpanel for 6k lights....2k on each, about 15 amps of AC..those are also on their own respective breakers. And there are four 20 amp breakers in the sub for fans, a 600w to veg under and a dehumidifier which is 7 amps... my question is, is the 60 amp enough?
thanks for any response
MM

 

[rives]

For a continuous application (defined as 3 hours or greater), the code calls for 80% of the breaker rating as maximum unless it is a specially listed breaker for continuous duty. So, .8 x 60 = 48 amps on your breaker.

It looks like you are running your ballasts on 120v from your 15 amp estimate. If so, you are a little light on your estimate for your 6k of lighting - there are ballast losses to consider in addition to your actual lamp load. These will vary according to the type of ballast from about 3-10%, so if you figure 6600 watts/120v = 55 amps total, so just the lights are higher than desirable. If I misunderstood you and you are on 240v, 6600/240=27.5 amps.

The 600, with losses, will be around 3 (240v) to 6 (120v) amps. I don't have any experience with dehumidifiers, so I have no idea what the duty cycle on those is. Your fans are a question mark since you didn't state the size or number of them.

To answer your question, if you are running your lighting on 240, you are probably fine, but don't have much headroom. If your lights are 120v, then no, it isn't enough. The rule of thumb for calculating breaker size is (1.25 x continuous load amperage) + (non-continuous amperage) = minimum size, then move up to the next standard size breaker.

 

[blazeoneup]

For a continuous application (defined as 3 hours or greater), the code calls for 80% of the breaker rating as maximum unless it is a specially listed breaker for continuous duty. So, .8 x 60 = 48 amps on your breaker.

It looks like you are running your ballasts on 120v from your 15 amp estimate. If so, you are a little light on your estimate for your 6k of lighting - there are ballast losses to consider in addition to your actual lamp load. These will vary according to the type of ballast from about 3-10%, so if you figure 6600 watts/120v = 55 amps total, so just the lights are higher than desirable. If I misunderstood you and you are on 240v, 6600/240=27.5 amps.

The 600, with losses, will be around 3 (240v) to 6 (120v) amps. I don't have any experience with dehumidifiers, so I have no idea what the duty cycle on those is. Your fans are a question mark since you didn't state the size or number of them.

To answer your question, if you are running your lighting on 240, you are probably fine, but don't have much headroom. If your lights are 120v, then no, it isn't enough. The rule of thumb for calculating breaker size is (1.25 x continuous load amperage) + (non-continuous amperage) = minimum size, then move up to the next standard size breaker.

From my understanding the poster has a 60 amp double pole breaker hooked up to a sub panel. I'm going to assume that by this he means he installed a sub panel running at 240v from a 60 amp double pole breaker in his main panel. In the sub panel he will have 3 30 amp single pole breakers. 2 for 4 1k lights, and one for other equipment. This will be fine as long as the load is balanced in the sub panel. Only thing that would need changed is the 3rd 30 amp single pole breaker. Swap it out for 2 20 amp single pole breakers and run one off each leg in the sub panel.

To the original poster Mike Myers

If you want to run your equipment at 120v as stated just make sure you balance the load in the sub panel. By this I mean you would install 1 30 amp single pole breaker on one leg of the sub panel for 2 of the 1k lights. Then install the other 30amp single pole breaker on the other leg of the sub panel for the other 2 1k lights. Also instead of using a 3rd 30 amp single pole breaker for your other equipment, use 2 20 amp single pole breakers one installed on each leg of your sub panel and this will balance your loads and allow you to run your equipment at 120v using the 60 amp double pole breaker in the main.

Balancing the load between the legs on your sub panel will allow you to run the equipment at 120v while still maintaining a balance and evenly distributing the power to your 60 amp double pole breaker in the main panel. Thus preventing an overload which would take place if you install everything on one leg of the sub panel at 120v.

You will still need to do the math as stated in the post I quoted above to make sure you don't go over the 80% usage recommendation. Good luck with your endeavor.

It would look like this.

main panel 60 amp double pole breaker-----240v-------subpanel-----left leg----30amp single pole breaker----20amp single pole breaker----right leg----30amp single pole breaker----20amp single pole breaker.

Even distribution of the 120v load works fine.

 

[Mike Myers]

For a continuous application (defined as 3 hours or greater), the code calls for 80% of the breaker rating as maximum unless it is a specially listed breaker for continuous duty. So, .8 x 60 = 48 amps on your breaker.

It looks like you are running your ballasts on 120v from your 15 amp estimate. If so, you are a little light on your estimate for your 6k of lighting - there are ballast losses to consider in addition to your actual lamp load. These will vary according to the type of ballast from about 3-10%, so if you figure 6600 watts/120v = 55 amps total, so just the lights are higher than desirable. If I misunderstood you and you are on 240v, 6600/240=27.5 amps.

The 600, with losses, will be around 3 (240v) to 6 (120v) amps. I don't have any experience with dehumidifiers, so I have no idea what the duty cycle on those is. Your fans are a question mark since you didn't state the size or number of them.

To answer your question, if you are running your lighting on 240, you are probably fine, but don't have much headroom. If your lights are 120v, then no, it isn't enough. The rule of thumb for calculating breaker size is (1.25 x continuous load amperage) + (non-continuous amperage) = minimum size, then move up to the next standard size breaker.

hey rives thanks for the response, this is where i get confused...the 60 amp breaker is 240v that runs the subpanel...so the whole subpanel is run off 240 but the breakers on the subpanel are 110, how does that affect the load?

 

[Hammerhead]

? if those are 120v only breakers they should not be used.. 3 30a breakers 2 lights per breaker on 240v.. Im upgrading now \. I just installed a 50a breaker that will go to my controller it has a 30a breaker in it. I use 3 600w lights,Scrubber,fans,AC is on anoter 120v line that thing pulld 12a.....

 

[rives]

hey rives thanks for the response, this is where i get confused...the 60 amp breaker is 240v that runs the subpanel...so the whole subpanel is run off 240 but the breakers on the subpanel are 110, how does that affect the load?

Mike, 240v is two "legs" or more properly, "phases", of 120v. If you connect a load from one of these phases to the other, it will be running on 240v. The neutral (white wire) comes off of a "center tap" on the transformer, internally located midway between the two hot legs, and will provide you with 120v when the load is connected from this wire to either one of the hot legs. Residential services are 240v with a neutral, and the panels are set up so that you can run either 240v or 120v to your loads.

Using 240v is desirable for large loads because the amperage, or current, is cut in half. A 1000 watt load on 240v will pull a bit over 4 amps whereas on 120v it would pull over 8. Due to the way that electricity works, the wattage remains constant. Amperage x Voltage = Wattage. The amperage being reduced allows you to run smaller wire for a given load, but since the wattage remains the same, it still costs you the same amount to run it. This is why the power company charges for wattage, rather than amperage. The idea that running things on 240v is cheaper than running them on 120v is incorrect - the savings is in the installation costs because of the smaller conductors, conduit, etc.

It is desirable to keep your 120v loads "balanced", which means having equal loading on each phase. This makes the load that the transformer sees more equivalent to a 240v load, and works the components equally. For instance, a 36,000 watt, 120v load on a 200 amp service equally distributed between the two phases would pull 150 amps on each leg. However, if it was all on one phase, it would pull 300 amps on that that phase and would drastically overload the service while trying to supply the same amount of power.

? if those are 120v only breakers they should not be used.. 3 30a breakers 2 lights per breaker on 240v.. Im upgrading now \. I just installed a 50a breaker that will go to my controller it has a 30a breaker in it. I use 3 600w lights,Scrubber,fans,AC is on anoter 120v line that thing pulld 12a.....

HH, as you can see from the above information, your post is incorrect. A 120/240 panel gives you the option of using either voltage and thus, single or double-pole breakers.

 

[Hammerhead]

Did you not see the ???????? I never seen a 120v only breaker... or the other part 2 1k ballest on a 30a breaker. Thats only 10a per breker @240v

 

[rives]

Did you not see the ???????? I never seen a 120v only breaker...

I saw it, but had no idea what you meant by it. 120v breakers are single-pole breakers and only stab onto one buss in the panel. 240v breakers are double-pole, have stabs for both busses, are usually twice the width of the single-pole units, and they usually have (at least in the lower amperage models) two operators on the front of the breaker tied together with a clip or bar so that both sides will operate in unison.

 

[Hammerhead]

Yes thats what I use... I did not understand what he was trying to say.. If he is using 240v it has to be D-POLE.. I have 0 single pole breakers in my box...

Correction there single pole one stab but have 2 brakers.I had to redo my box to get the new 50 to fit.

 

[rives]

HH, if that was a question about breaker sizing that you edited into your post above, yes you could get by with much smaller breakers than 30 amps (also smaller wire, and receptacles and plugs with lower amperage ratings) if you are limiting each circuit to (2) 1000w lamps running on 240v. It could be done on 15a breakers and 12 gauge wire very comfortably. Actually, 14 gauge would conform with code, but personally I never use less than 12 gauge on plug circuits.

 

[Hammerhead]

I just installed 8-4 for the 30a line

 

[rives]

I just installed 8-4 for the 30a line

Well, the good news is that if you ever want to expand you could run (5) 1000w lamps on your 30a/240v circuits.

 

[Hammerhead]

yes thats why I did it but it wont be 1k.. I love my 600 I will be adding more of these..

 

[blazeoneup]

? if those are 120v only breakers they should not be used.. 3 30a breakers 2 lights per breaker on 240v.. Im upgrading now \. I just installed a 50a breaker that will go to my controller it has a 30a breaker in it. I use 3 600w lights,Scrubber,fans,AC is on anoter 120v line that thing pulld 12a.....

Actually he only need to swap out one of the 30 amp single pole breakers for 2 20 amp single pole breakers and balance the load in his sub panel.

Read my post a few post up for details. Mike Meyers check my original post up near the top of this thread for details on how you can make the install you have work running everything 120v.

 

[Hammerhead]

When I upgrade I overkill the install with big breakers and big power line even though im only using 30a. If I need the power later I have it to add stuff with no worries

 

[blazeoneup]

When I upgrade I overkill the install with big breakers and big power line even though im only using 30a. If I need the power later I have it to add stuff with no worries

Nothing wrong with having room to upgrade. Nothing wrong with using what's there as long as it's acceptable.

 

[rives]

Actually he only need to swap out one of the 30 amp single pole breakers for 2 20 amp single pole breakers and balance the load in his sub panel.

Read my post a few post up for details. Mike Meyers check my original post up near the top of this thread for details on how you can make the install you have work running everything 120v.

Blaze, you are correct here - nice catch. I obviously got lost bouncing back and forth between the two voltage calculations. Mea culpa! I'm not sure how I missed seeing your post the other day, but I did.

Another way to look at it would be that he has roughly 11,500 watts available after applying the 80% factor. Without the fans, but with the dehuey and ballast losses, he is running @ 8000-8250 watts. It will indeed work fine as long as it is properly balanced. My preference would be to have a bit more for future additions, but I like to overbuild things.

 

[blazeoneup]

I'm not sure how I missed seeing your post the other day, but I did.

My preference would be to have a bit more for future additions, but I like to overbuild things.

You didn't miss it, There was a problem with my account the other day and my post were only viewable by me. So it's my fault everyone missed the post

Nothing wrong with some lead way for upgrades an future additions.