I want to add an additional panel to my electric service. I have a 200amp service that is almost full (i.e. most of the circuit breakers have been installed) so the panel is difficult to work with to add new wires.
Is it possible to add an addtional 100amp(?) panel by tapping directly into the service line coming in from the street? or does the new panel ALWAYS(by law) have to be off of the existing panel. If it is "supposed" to be off the existing panel, what might go wrong if I tap into the main feed wire anyway? i.e. is it just a convention or is it truly a safety issue?
How did you plan on "tapping" into the main line?
If you did not change the service cables to one good for 300Amps, you'd possibly have a serious condition on your hands. If all you need is more circuit breaker space, feed the 100 amp panel off a 2-pole breaker in the 200 amp panel. You'll still be limited to a total of 200 amps, but that's all your main cable is good for anyway.
>>How did you plan on "tapping" into the main line?
Hadn't thought that far ahead actually, but I think you answered the real question anyway, and that is, if I add a 100 amp panel, in addition to my 200 amp panel, I could theoretically draw as much as 300 amps, but my feed wire is probably only rated for 200, so it may overheat? Is that more or less what might happen?
On the otherhand, if I add a 100amp breaker that feeds a new panel, it will give me more circuits, but would never draw more than 200amps? correct?
That all makes sense to me (assuming its true the way I summarized it), but I wasn't aware that the cable from the street itself was a variable and would possibly need to be upsized....
Definitely don't want to create any safety issues. I don't have room to add a 100amp breaker, but now that I think about it I could remove a few circuits to make room, and then move those circuits onto the new box I guess...
Your new sub-panel will be protected by the initial panel's 200amp mains. You're in a whole messa trouble if you're blowing those! Make sure you follow the correct installation procedures regarding neutrals/grounds for a sub-panel.
Sub panel fed by a 100 amp breaker. Of course that won't give you an extra 100 amps, but more spaces. Some breaker vendors (Cutler Hammer, for one) make 'double whammy' breakers which put 2 in the place of one old breaker, or 4 in the place of 2. That would be quicker & cheaper.
Yes, but panels are limited as to how many tandems, twins or "double whammy" breakers you can add to them. Some Panels will not accept them at all, legally and safely.
Sure, you should never exceed code, etc., but if you happen to have a panel which can hold twins, and you need a few extra circuits and can fit the twins in (and meet code) then its worth mentioning. Its an awful lot cheaper than putting in a whole new panel, and since nobody mentined it yet, I figured I would.
Now, my CH panels say that I can fill each slot with a twin, so I see to have loads of options (pun intended), even though I have 2 sub panels in the house and one in my small barn.
No such thing (that I know of) as a "current day" panel that you can put twins in every slot, except for a 20 circuit 200 Amp panel or a 12 circuit 100 amp panel. All legal twins have a rejection tab and are labeled "Class CTL Breaker". There are twins out there labeled "NON-Class CTL breaker for replacement use only".
Let me explain.......UL lists these panels in conformity to the NEC. One 200 amp panelboard can not exceed 42 spaces. And 100 Amp panels can not exceed 24 spaces(I think it is), usually they are listed at 20 circuits for 100 amps.
If you have a 30 circuit 200 amp panel, you can install 10 maybe 12 twins. Not to exceed the 42 space rule.
<font color="blue"> 408.15 2002 NEC
A lighting and appliance branch-circuit panelboard shall be provided with physical means to prevent the installation of more overcurrent devices than that number for which the panelboard was designed, rated, and approved</font color>
Oh, I'm sure you know your code cold. I'm up in the snowy north so the rules may be different. Up here, a 20 position CH panel is sold as supporting 40 circuits if you use twin breakers. There is no caution on the box on in the instructions as to using a certain number, and all the details are there (in english & french) in both the instructions and on the warning label on the box.
So, I assume that you can fill up a box up here, but we are kinda slow, anyways. [img]/forums/images/icons/laugh.gif[/img]
In any event, my point was simply that the original post concerned needing to add new circuits. Yes, you could add a sub panel. But, hypothetically, lets says he had a 20 circuit CH panel with compatible twin breakers, and he could legally put one or more twins into his box. My point was, simply, that this may be an option worth knowing about.
No intent to break the law or violate the code. Just a cheap safe, solution worth mentioning.
Reply With Quote
