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Old 02-13-2010, 01:47 AM   #1
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Question about outdoor panel, conduit and derating wire


I will try to break my question into several ones in order to avoid confusion.

Q1. In order to use an outdoor 200A breaker panel, wires from indoor appliances must be put inside a conduit to reach the panel. Is it correct?

Q2. Is schedule 80 PVC conduit allowed for this case?

Q3. If he puts these wires in a conduit to reach the outdoor panel, should the electrician consider derating wires? How to avoid the mess?

Thanks a lot! Sorry for my questions if they are stupid.

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Old 02-13-2010, 02:45 AM   #2
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Question about outdoor panel, conduit and derating wire


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Q1. In order to use an outdoor 200A breaker panel, wires from indoor appliances must be put inside a conduit to reach the panel. Is it correct?
Typical yes some case some use the UF { underground feeder } cable as well as long it is marked " sunlight resent " {spelling }

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Q2. Is schedule 80 PVC conduit allowed for this case?
Yes it can but normally if not going to get damaged one way or other the Schedule 40 PVC will do the task just fine.

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Q3. If he puts these wires in a conduit to reach the outdoor panel, should the electrician consider derating wires? How to avoid the mess?
We do go by the numbers of conductors {wires } in the conduit we count current carry conductors { CCC } but most case magic numbers useally appair useally at 4 CCC but keep in your mind it may affect depending on how it set up.

Basically here a quick run down for derating.

4 to 6 conductors at 80%
7 to 9 conductors at 70%
10 to 20 conductors at 50%

so I will give you a example

I will use 10 X 4.0mm≤ ( 12 AWG ) by the codebook it typically rated for 20 amp so with 10 conductors in there you reduce down to 10 amp per conductors it will affect simauir way with other conductor size.

as you see the more the conductors in the conduit the more it will derate the key issue is heat effect.

Merci,Marc

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Old 02-13-2010, 05:04 PM   #3
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Question about outdoor panel, conduit and derating wire


Are you saying the outdoor 200a panel is not mounted on the exterior of the house? That it is in some way seperated from the house?
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Old 02-13-2010, 05:47 PM   #4
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Question about outdoor panel, conduit and derating wire


Let make it clear with OP's { Pttcc } situation I do not know if he is using all in one load center with meter socket as one unit or he have seperated units nomrally I know a bit of Californine set up typically use all in one box for most of the resdentail useage.

I wish the OP come back and give us little more details to make sure we are on right page.

Merci,Marc
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Old 02-13-2010, 08:36 PM   #5
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Question about outdoor panel, conduit and derating wire


Thanks a lot to frenchelectrican!

I have stripped my old house to studs. So it's a good time to rewire everything (including upgrade service panel from 30 amp to 200 amp). Yeah, an old house with 30 amp fuse box.

I fired my electrician because I noticed he was fooling around. I will hire another one, but I'd better understand more details by myself this time.

I have two options about the main panel:
option 1: use an outdoor all-in-one box with a meter socket. However, I don't think it's convenient to wire all indoor appliances to the breaker panel.
option 2: use a shutoff switch next to meter. Put three 2/0 + #6 grounding though a 2" conduit to an indoor breaker panel 15 feet away.

I like option 2 more. What do you think?



I have another question:

Is EMT conduit allowed to connect meter, shutoff switch and main breaker panel? I think EMT is very thin and weak (correct me if I am wrong). But IMC conduit is too heavy. I don't know what kind of conduit is allowed (or better suited for my house.)

Thanks a lot!
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Old 02-13-2010, 09:16 PM   #6
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Question about outdoor panel, conduit and derating wire


If you really want to put all your breakers inside you can feed a 200a panel inside through 2" EMT, 2" flex, 2" pvc schd 40 or 3/0 CU romex. They're all accepted NEC wiring methods.

I'd use an All in One outside because if I install the circuitry there will never be a problem with tripping breakers unless my son sticks a fork in a receptacle. I like my interior space.

Not sure regarding your first post but conduit is not necessary in a residence less than 4 stories high for in wall wiring. Romex works just fine. Check the stapling to make sure the cables can move and are not pinched. Especially in California. Things sometimes want to move.
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Old 02-13-2010, 11:08 PM   #7
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Question about outdoor panel, conduit and derating wire


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Not sure regarding your first post but conduit is not necessary in a residence less than 4 stories high for in wall wiring. Romex works just fine.
How does an electrician run wires into an outdoor breaker panel without conduits but still keeps them weather-proof?


Last edited by pttcc; 02-14-2010 at 01:34 AM.
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Old 02-14-2010, 02:13 AM   #8
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Question about outdoor panel, conduit and derating wire


hmmmm.

Maybe we're talking about two different things. I am assuming that by "outdoor panel" you are reffering to a panel flush mounted in or surface mounted on the exterior wall of the house. If the panel is flush mount, the cable or conduit is installed in the wall and enters the panel inside the wall into the sides, top or botttom of the panel. If the panel is surface mount, the cables and /or conduits enter the panel through the back. Or you build a pop-out and enter through the top or bottom.

If the panel is remotely located than conduit is the best answer. I prefer PVC. If either end of the conduit is exposed to damage where it breaks ground then I would use rigid pipe as my riser. Important to note that you are restricted to one conduit carrying power into the house and you will need to mount a subpanel at the location where the conduit enters the house.

Are we on the same page?
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Old 02-14-2010, 02:39 AM   #9
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Question about outdoor panel, conduit and derating wire


With all in one meter/breaker box it can be done in two ways one is surfaced mounted and punch a hole back of breaker box so you can bring in cables in from wall cavity or .,,

Countersink it which it mean it will sink half to 3/4 way in the wall so you can able bring in new cables in but it will be little tricky to bring in lateral if you are on UG set up but overhead riser it pretty easy straight shot up.

otherwise you have meter socket outside { check with your local codes some may want have outdoor main breaker with meter socket } and load centre inside short as possible if not short as possible then you must install the main breaker or get meter socket with main breaker below of it.

with that option from main outdoor breaker box or meter / main set up from meter / main to load centre you have to run 4 conductor no expections on this one.

I know couple of members they are electrician from that area like Californie or Arizona area they are useing simauir set up so one of them will chime in if they are here.

Oh last thing check with your inspector and POCO for meter location and type of socket with main breaker included due some area the POCO have diffrent rules and local area may have diffrent rules to deal with it.

Merci,Marc
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Old 02-14-2010, 09:11 AM   #10
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Question about outdoor panel, conduit and derating wire


Couple things

If punching holes in the panel enclosure for romex entry, you must use a listed connector and conform to the maximum allowable number of cables in that conductor (usually two cables). If using conduits, remember that there is a maximum number of current carrying conductors allowed in a conduit before you must begin derating their current carrying capacity. Increasing the size of the conduit allows more conductors but does not affect the need for derating. Therefore, it is usually best practice to use more and smaller entry holes for conduits or romex.
3/0 romex or THHN should only enter a panel from the top, bottom or upper or lower sides (never the back). The heavy gauge of the wire does not allow the tight bending radius needed for entering from the back.

Three conductors are OK when using an appropriate metal conduit that is properly installed to act as the grounding conductor.
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Old 02-15-2010, 10:51 AM   #11
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Question about outdoor panel, conduit and derating wire


Wow... you guys are so nice and helpful. I didn't expect I can get answers so quickly.

Thanks a lot!

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