Max loading on two pole breaker stabs

[brianecamp]

I've got a situation that involves how much loading to allow on a 100 amp main breaker panel.

I'm understanding that max loading on the busbar is limited to 50% of the rating of the panel.

So, the question is can I install a range rated at 50 Amps across from any other circuit breakers in the panel?

This house has been through quite a bit and the previous owner successfully sued kcpl in the past.

The current ower had a near fire due to overloading, but is now up to code and has passed a city inspection and we have managed to put his system back together without any loading over 50 amps per stab.

He is extremely concerned about heat, at this time he is up and running.

That being said, he is wanting to install a 50 Amp range in place of his 30 amp system and we are out of spaces unless I can locate breakers exceeding the 50% limit.

thanks

brian

 

[petersonra]

I never heard of the 50% limit.

Is this some limit of this particular panelboard?

Maybe it is time to change it out.

 

[charlie b]

You can run 100 amps of load on a 100 amp panel. But let's be clear: I am talking about "calculated load." That calculation requires you to count 125% of any continuous loads (and a range is not continuous, but a water heater probably will be), plus 100% of any non-continuous loads.

You did not give details, so I will assume your panel is a 120/240 volt, single phase, 100 amp panel, that the existing range uses a 2-pole, 30 amp breaker, and that the new range requires a 2-pole, 50 amp breaker. If that is all true, then you can take out the 30 amp breaker and replace it with a 50 amp breaker, naturally changing the wire size to match, as long as this replacement range does not put you over the limit of 100 amps on the load calculation. If you haven't done a load calculation, you should start there.

I don't know if this answers your question or not. If not, please clarify the question.

Welcome to the forum.

 

[brianecamp]

in this area the power company supplies 100, 200, 400 etc. sized power systems

at some time individuals were installing 125 amp panels, so when it was time for an upgrade to 200 amps, they ended up with a 125 amp main lug panel and a cleaver idea - why not use the 125 amp panel as a sub panel for the basement addition ?

in order to use the 125 amp rated main breaker panel or the number of circuits provided by one you would have to fuse it in the 200 amp panel on a 125 amp breaker.

but, that exceeds the 50% rule on the busbar of the 200 amp panel - i actually found that rule in relation to a tanning bed installation a couple of years ago and I am looking for it again

thanks

mark

 

[roger]

There is no 50% rule and if the panel was to small (say a 125 amp panel ) when a service upgrade is perfromed the panel would simply have to be changed out to match the service size.

Roger

 

[brianecamp]

right, the scenario is that the upgrade came with the 200 amp panel and now there is the extra 125 amp panel that the customer desires to use as a sub panel remote from the existing service.

so, how do you fuse the 125 amp panel on the 200 amp rated busbar

the scenario above is just an example - my particular situation involves a 100 amp rated main breaker panel and the customer is wanting to add a 50 amp range.

So the question is can the range breaker be installed across from any other breakers, or is there a limit to load on any stab

thanks

 

[don_resqcapt19]

There are rules for the maximum total of the breakers that are connected to a single bus "finger". I don't think I have ever seen a 50% rule, but most panels have a maximum number of amps that are permitted on a "finger".

 

[don_resqcapt19]

...So the question is can the range breaker be installed across from any other breakers, or is there a limit to load on any stab

thanks

Look at the labels on the panel or the instructions that came with it.

 

[kwired]

You can run 100 amps of load on a 100 amp panel. But let's be clear: I am talking about "calculated load." That calculation requires you to count 125% of any continuous loads (and a range is not continuous, but a water heater probably will be), plus 100% of any non-continuous loads.

You did not give details, so I will assume your panel is a 120/240 volt, single phase, 100 amp panel, that the existing range uses a 2-pole, 30 amp breaker, and that the new range requires a 2-pole, 50 amp breaker. If that is all true, then you can take out the 30 amp breaker and replace it with a 50 amp breaker, naturally changing the wire size to match, as long as this replacement range does not put you over the limit of 100 amps on the load calculation. If you haven't done a load calculation, you should start there.

I don't know if this answers your question or not. If not, please clarify the question.

Welcome to the forum.

He is asking if there is a maximum load per space in the panel. The label attached to the panel should tell you. Aluminum bus panels are more likely to have a lower limit than copper bus panels. A breaker rated over 125 amps often uses additional spaces and is a different application with different instructions than a breaker that uses one space per pole.

 

[kwired]

right, the scenario is that the upgrade came with the 200 amp panel and now there is the extra 125 amp panel that the customer desires to use as a sub panel remote from the existing service.

so, how do you fuse the 125 amp panel on the 200 amp rated busbar

You must have 125 amp or less overcurrent protection ahead of the 125 amp panel - or a main breaker in said panel.

 

[roger]

So the question is can the range breaker be installed across from any other breakers,

thanks

Unless there are some manufacturers instructions that say it can't, yes it can.

Roger

 

[hillbilly1]

right, the scenario is that the upgrade came with the 200 amp panel and now there is the extra 125 amp panel that the customer desires to use as a sub panel remote from the existing service.

so, how do you fuse the 125 amp panel on the 200 amp rated busbar

the scenario above is just an example - my particular situation involves a 100 amp rated main breaker panel and the customer is wanting to add a 50 amp range.

So the question is can the range breaker be installed across from any other breakers, or is there a limit to load on any stab

thanks

You are only limited by the manufactures labeling, if it says you can use even a 150 amp breaker (unlikely though) on the 200 amp buss, then you can do it. There is no code rule I know of that limits you to a certain percentage. (other than manufactures instructions)

 

[brianecamp]

Right, thank you all for your timely replys . . .

I contacted seimans today - this was a value pack 100 amp mb 20/20 space panel aluminum bus . . .

the tech support engineer stated that the the max loading per stab was 110 amps

wow !!!

I had no idea, I generally design my systems much, much lighter . . .

than means I'm good to go on some extra circuitry which the customer needs and wants without a 200 amp upgrade or a subpanel install . ..

I must have seen that 50% issue when I was specking out equipment for a tanning bed a couple of years ago . . .

it was rated at 3phase 70 amps and I needed to install a phase converter but was limited with the existing power at the facility . . .

also, I think I recall that it was the cut sheet of the prospective equipment, and not the nec which indicated the limitation (ie 50% loading)

thanks again, i think this one is solved !

brian

 

[kwired]

Right, thank you all for your timely replys . . .

I contacted seimans today - this was a value pack 100 amp mb 20/20 space panel aluminum bus . . .

the tech support engineer stated that the the max loading per stab was 110 amps

wow !!!

I had no idea, I generally design my systems much, much lighter . . .

than means I'm good to go on some extra circuitry which the customer needs and wants without a 200 amp upgrade or a subpanel install . ..

I must have seen that 50% issue when I was specking out equipment for a tanning bed a couple of years ago . . .

it was rated at 3phase 70 amps and I needed to install a phase converter but was limited with the existing power at the facility . . .

also, I think I recall that it was the cut sheet of the prospective equipment, and not the nec which indicated the limitation (ie 50% loading)

thanks again, i think this one is solved !

brian

Not trying to put you down but think about something here. If you were not allowed to plug in anything larger than say 60 amp breaker then there would be no point in them making 70, 80, 90, 100, 110, or 125 amp breakers as there would be no place acceptable to use them. 150 - 225 amp breakers for most miniature frame breaker panels usually take 2 pole spaces per line and are a different situation. They are also something not seen too often - especially in dwellings.