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Re: Panel Schedule - 10% Rule ??? [Re: acetoday] #168615 09/10/07 11:27 AM
Joined: Jul 2004
Posts: 9,496
gfretwell Offline
Originally Posted by acetoday

What confuses me about this issue is if you can only fill a panel with 42 circuits then why do they make panelboards with greater then 42 circuits?

Canada does not have that rule,

Greg Fretwell
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Re: Panel Schedule - 10% Rule ??? [Re: acetoday] #168621 09/10/07 06:12 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
The 42 circuit limitation applies only to 'appliance' panels .... that is, panels whose circuits have neutral wires. That's what the 10% rule defines. Other panels are "power" panels.

As mentioned above, this arbitrary rule is about to leave us.

Also as mentioned above, 'legal' and 'good design' are not always the same thing. Personally, I will even go so far as to assert that a design that is deliberately intended to 'push the code' envelope is a bad design for every other purpose.

Re: Panel Schedule - 10% Rule ??? [Re: renosteinke] #168669 09/12/07 12:21 PM
Joined: Aug 2004
Posts: 186
NJ Wireman Offline
imo i would go with the MDP, i had this happen about 1 1/2 years ago to me on a job. I landed up going with a mdp in the basement and several panels though out the building. i would say cost can be slightly high or if you look at the fact of home run lengths slightly lower depending on your situation. Either way i feel this is a neater and much safer install for the homeowner. They are tought in an emergency go to the mdp and kill it one panel at a time then the main! Not the best of practices but it works rather then them running around a house trying to kill each little panel when they don't even know which one is causing the problem. i did mine this way and the inspector praised my design and install!!!

Re: Panel Schedule - 10% Rule ??? [Re: NJ Wireman] #168700 09/13/07 06:26 AM
Joined: Dec 2001
Posts: 2,484
Texas_Ranger Offline
Here (Austria) the planning standards say you can only fill new panels to 80% to leave room for future expansions. IMHO a good idea (even though I don't always stick to it when doing work in my own home).

Re: Panel Schedule - 10% Rule ??? [Re: Texas_Ranger] #168704 09/13/07 08:52 AM
Joined: Jun 2004
Posts: 202
32VAC Offline
I'm a big believer in fitting the "next size up" board to alllow for expansion.

Case in point: with the low cost of split system airconditioners, it is quite easy to fill up a board with just one service call which then fils any spare poles in the board, some houses I have worked on have ended up with a sub-board being fitted just for split aircons & 15 amp welder/caravan outlets while the hot water service, cooking appliances, power & light circuits fill the original boards.

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