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Old 03-15-2008, 06:21 PM   #31
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burying wire underground


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Originally Posted by 220/221 View Post
I thought that referred to the different voltages as described within that section.


Am I misunderstanding something?



Utility companys here in AZ stopped direct burying cable in the 80's. Everything is in PVC. I suspect they spend a LOT of time repairing gopher bite marks.

Must be an area specific thing again. Our utilities never use conduit, it is always direct burial. I would say 90% of the contractor installed services are direct burial also. Our area is mostly clay and the only thing we concern ourselves with is that there are no rocks up against the conductors. When it freezes around here the rocks tend to move and after a few years they can wear through them. The most interesting thing about this site is the differences in installations around the country. The most annoying thing is that everybody thinks their way is the only way to do things.

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Old 03-15-2008, 06:49 PM   #32
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Utilities still use alot of direct burial wire here in Georgia, I have even watched them splice underground wire with crimp connectors, insulate it with heat shrink and put it back in the ground. I am not saying it is right, just saying I have seen it done. Most of the circuits run to water wells in the rural areas around here are run in UF cable, as you said failure happens, but not often.
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Old 03-15-2008, 06:49 PM   #33
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They are talking about being allowed to run different feeders or branch circuits that are not also the same characteristic. I could run a single phase feeder and a 3 phase feeder to a building but not 2 single phase feeders or branch circuits from another building or dwelling. Thats how I have always understood that section of code. It would seem to be directed more towards commercial applications IMO.
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Old 03-15-2008, 06:50 PM   #34
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Not to be annoying but.....

If keeping rocks off the cable is a concern, conduit would be a good solution. Otherwise you are depending on the lowest guys in the construction food chain to assure a proper installation. The guy throwing dirt in the trench generally doesn't think about the integrity of the cable 20-50 years from now.

The way I see it is, you should be building a system that will be in service for 50 to 100 years. When the cable needs to be replaced, just pull it out/in without tearing the hell out of everything.
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Old 03-15-2008, 06:53 PM   #35
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the OP was asking if it was alright to run a 240v 2 wire circuit and a 120v circuit in the same pipe. I have never looked it up, it is just something I do not do(running different voltage circuits in the same pipe).
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Old 03-15-2008, 06:56 PM   #36
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Quote:
They are talking about being allowed to run different feeders or branch circuits that are not also the same characteristic
They seem to define "characteristics" as "voltages, phases or frequencies"

I read it as (one) 240V and (2)120V (MWBC)


Beats me .....I doubt I will ever have to argue the point.
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Old 03-15-2008, 06:59 PM   #37
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Just put in a sub-panel and forget the multi circuit deal, easier, quicker, less expensive, and room for future expansion.
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Old 03-15-2008, 06:59 PM   #38
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it is just something I do not do(running different voltage circuits in the same pipe).
He was actually asking more than that as it is going to a separate structure.



But Jimmy...if you run an 240V AC circuit and need to add the 120V outlet as required, you would run separate conduits? After all, they are not really different voltages. All 120 to ground, 208 240 between them...right?
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Old 03-15-2008, 07:28 PM   #39
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Originally Posted by 220/221 View Post
Not to be annoying but.....

If keeping rocks off the cable is a concern, conduit would be a good solution. Otherwise you are depending on the lowest guys in the construction food chain to assure a proper installation. The guy throwing dirt in the trench generally doesn't think about the integrity of the cable 20-50 years from now.

The way I see it is, you should be building a system that will be in service for 50 to 100 years. When the cable needs to be replaced, just pull it out/in without tearing the hell out of everything.

Not to be annoying but...... It's not really a concern, as in I don't stay up nights worrying about it. It's just if we have a large rock, we don't throw it on top of the wire, pretty simple. We don't really pull services in and out all the time. If it's a service upgrade and you had installed it 50 years ago the conduit would probably be undersized for the new 200 amp or whatever anyways. Most people nowdays aren't remodeling 50 year old houses around here, they're dozing them and staring over. To each his own.
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Old 03-15-2008, 07:59 PM   #40
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Yes I do see what you mean but I believe what 225.30 (D) is saying is differences in source voltages. For instance if I have a 120/240 volt mwbc to a building from another but lets say on the outside of that building I have 277 volt canopy lights I could run a 277/480 feeder or branch circuit at 277 volts to the building along with the mwbc.

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Old 03-15-2008, 09:51 PM   #41
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Quote:
I believe what 225.30 (D) is saying is differences in source voltages.


Maybe,,,,but it doesn't say source.
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Old 03-16-2008, 12:31 AM   #42
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Does it have to?
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Old 03-16-2008, 02:04 AM   #43
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Seems like it would.

Diference in voltages and difference in source voltages mean different things.

Don't they ?

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