Nec 2008 code

[Wishiknew]

I'm having an issue with locating the article that would clarify what the maximum % of the main service panel OCPD can be use for a tank-less Hot water heater. The inspector said 50 % of the main service panel OCPD is the maximum any branch circuit can be used. If I have a 200 amp main then the total would be 100 Amps max allowed for this branch circuit. I have had no luck in verifying this in the 2008 code book.
Could sure use a little help finding the right Article.
Thanks

 

[Dennis Alwon]

I'm having an issue with locating the article that would clarify what the maximum % of the main service panel OCPD can be use for a tank-less Hot water heater. The inspector said 50 % of the main service panel OCPD is the maximum any branch circuit can be used. If I have a 200 amp main then the total would be 100 Amps max allowed for this branch circuit. I have had no luck in verifying this in the 2008 code book.
Could sure use a little help finding the right Article.
Thanks

I doubt you will find it in the NEC but look at the panel. It will usually state on the cover what the max size is per stab. Most that I have seen will take 125 amp

 

[kwired]

You do need to consider that there are other loads, but if your load calculations for everything else only comes to 50 amps you still have 150 left on a 200 amp supply.

Maximum individual breaker - depends on the panel. Many "loadcenters" accept up to 125 amps per pole, but some do have 150 - 225 amp breakers that use two spaces per pole so you can possibly use a 200 amp breaker in a 200 amp panel, though by nature it sort of limits what other load is able to be supplied by same panel.

 

[Wishiknew]

I doubt you will find it in the NEC but look at the panel. It will usually state on the cover what the max size is per stab. Most that I have seen will take 125 amp

Thanks for the answer but I'm not sure what STAB is.
My inspector said you can not use more than 50 % of the main breaker for any one branch circuit. I was looking for the code article that backs that statement. He is the inspector and I do need to follow his decision. I would just like to know where in the code this is spelled out. If you do the math everything will work just fine so I don't know where the 50% comes in.
Thanks

 

[kwired]

Thanks for the answer but I'm not sure what STAB is.
My inspector said you can not use more than 50 % of the main breaker for any one branch circuit. I was looking for the code article that backs that statement. He is the inspector and I do need to follow his decision. I would just like to know where in the code this is spelled out. If you do the math everything will work just fine so I don't know where the 50% comes in.
Thanks

He is also human and can be wrong. There is no such rule. A 200 amp panel can have 200 amps of load all on one load breaker as long as the breaker/bus combination is designed to carry full 200 amps. Like I said before most times when you have over 125 amp breaker in a "loadcenter" panel, the device uses more then one space per pole.

When they mentioned "stab" they meant any one pole breaker position of the panel bus.

 

[luckylerado]

...I don't know where the 50% comes in.
Thanks

I am going to put my money on a misinterpretation of 210.23(A)(2). I have not done a tankless that was not subdivided into multiple smaller circuits. If you are feeding it with a single 100 amp ckt. I would bet there are 3 fused circuits inside the unit so your 100 amp circuit is a feeder maybe??

 

[Ponchik]

As stated earlier the maximum branch breaker size can not exceed XXamps. You can used up to 200Amps of the main breaker rating but you can only install 100A or 125A breaker for a feeder or for a branch circuit. Read the instruction label on the panel or check the instructions on manufacturer's website.

 

[iwire]

Just tossing this out here, the electrical inspector may be trying to enforce a local power company requirement.

 

[mwm1752]

Thanks for the answer but I'm not sure what STAB is.
My inspector said you can not use more than 50 % of the main breaker for any one branch circuit. I was looking for the code article that backs that statement. He is the inspector and I do need to follow his decision. I would just like to know where in the code this is spelled out. If you do the math everything will work just fine so I don't know where the 50% comes in.
Thanks

Another use of stab is plug in which describes the action in how the breaker is installed on the buss -- Simply ask for the code section or how he concluded his ruling -- Dennis has the most logical answer, you equipment has maximum breaker ratings the can be installed on the buss. If you find out your buss accepts up to 125 amp breakers use NEC 90.7 as your justification.

 

[Ponchik]

Just read the instructions on the panel.

 

[kwired]

Panel instructions may say 100 or 125 amps max on each position, but like I said twice now there are 150-225 amp breakers that take more then one position per pole, so unless the panel is not rated to accept those particular breakers you still could have a 200 amp main and a 200 amp feeder breaker in same panel.

 

[Wishiknew]

Wishiknew

Wishiknew

I am going to put my money on a misinterpretation of 210.23(A)(2). I have not done a tankless that was not subdivided into multiple smaller circuits. If you are feeding it with a single 100 amp ckt. I would bet there are 3 fused circuits inside the unit so your 100 amp circuit is a feeder maybe??

Yes, you are right. He is using 210.23(A) (2). The heater calls for 2 circuits controlled by 2-60amp dbl. pole breakers.
What he is telling me, because both circuits go to one piece of utilized equipment the total is 120 amps which is more than 50% of the main breaker, which is 225 Amps. He will allow me to install 2- 50 amp dbl. pole breakers which is what I will do. The manufacture of the heater recommends to install 2-60 Dbl. pole breakers. I just want a clear cut picture based on the NEC as to why he is saying 50 % of the main panel disconnect.
Thanks

 

[luckylerado]

Yes, you are right. He is using 210.23(A) (2). The heater calls for 2 circuits controlled by 2-60amp dbl. pole breakers.
What he is telling me, because both circuits go to one piece of utilized equipment the total is 120 amps which is more than 50% of the main breaker, which is 225 Amps. He will allow me to install 2- 50 amp dbl. pole breakers which is what I will do. The manufacture of the heater recommends to install 2-60 Dbl. pole breakers. I just want a clear cut picture based on the NEC as to why he is saying 50 % of the main panel disconnect.
Thanks

Well he is full of it. That section is strictly for 15 and 20 amp branch circuits supplying combination loads. He is in the wrong by a mile. How many furnaces have 2 60s or 2 60s and a 30.

 

[Sierrasparky]

Yes, you are right. He is using 210.23(A) (2). The heater calls for 2 circuits controlled by 2-60amp dbl. pole breakers.
What he is telling me, because both circuits go to one piece of utilized equipment the total is 120 amps which is more than 50% of the main breaker, which is 225 Amps. He will allow me to install 2- 50 amp dbl. pole breakers which is what I will do. The manufacture of the heater recommends to install 2-60 Dbl. pole breakers. I just want a clear cut picture based on the NEC as to why he is saying 50 % of the main panel disconnect.
Thanks

You need to talk again with this inspector claiming to be MR. code. He knows nothing of what he claims.
Oh and placing 50 amp breakers is not going to do anything to limit the heater draw only create issues.

Secondly if your Tankless water heater calls for 2 60 amp circuits, that is what you must supply. Not doing so could void your warranty but also cause you problems down the line. Such as tripping breakers.

The only way your inspector no it nothing can tell you your proposal is wrong is if your load calculations don't place you within the 200 amp panel.

 

[Wishiknew]

He has already told me he will not pass me on the final if I use 2-60 amp breakers.

 

[Sierrasparky]

I'd go to his boss or change it to the correct 60 amp ones once he leaves.

If you are fearing retaliation you have no worries if you follow all the other codes.
If you bow down to this power tripping idiot he will roll you over at every chance he gets.
I don't fear these guys. I don't get hot headed with them. Just sweet talk them. Show them how 210.xx does not apply. Section 210 is for the branch circuit itself and not the feeder. The inspector cannot take one code section and apply it to what ever at whim like some criminal code prosecutors do.


Good luck on your choice.

 

[luckylerado]

He has already told me he will not pass me on the final if I use 2-60 amp breakers.

Has he even read the code as written? It is not even open to interpretation. Usually I would concede something small like this just to get out the door but I would raise holy hell over this one. The equipment may literally not even function with 50s.

 

[kwired]

Has he even read the code as written? It is not even open to interpretation. Usually I would concede something small like this just to get out the door but I would raise holy hell over this one. The equipment may literally not even function with 50s.

If I felt inspector was incompetent I would stand up to what I feel is correct also. You start to give in to requests and demands that you know are wrong you are just setting yourself up for always having to change your work because of their incompetence. The sooner you get them straightened out or out of their position (either works) the better off you are, unless maybe you never expect to run into that individual again for some reason.

 

[Wishiknew]

Thanks everyone,
I'll sit down with him and we will talk this one out.