wire

user 100 · May 15, 2016

enireh said:
in the past three conductors was permitted to feed sub panel, now all are required to have a four wire feed yes?

Up thru 2005, yes. That changed in 2008- it's allowed only if it was existing, must have the egc for new sp's.

Carultch · May 15, 2016

iwire said:
:thumbsup:

I think I let one of my designs slip through the cracks with SER spec'd in an installation that is mostly above ground, and part of it had a 10 ft "dive" below ground through the conduit as it swept through a panelboard. That was built long ago, and I overlooked this rule without thinking about it.

Is there any particular reason / real life consequence as to why SER / SEU is not allowed underground even in a raceway? The constituent XHHW-2 wires inside of it would be allowed underground in a raceway on their own.

Would it be permissible to strip away the SER jacket and continue the constituent XHHW-2 wires underground in a raceway?

And is there any close equivalent of SER/SEU, that is rated for underground use?

electrofelon · May 15, 2016

Carultch said:
Is there any particular reason / real life consequence as to why SER / SEU is not allowed underground even in a raceway? The constituent XHHW-2 wires inside of it would be allowed underground in a raceway on their own.

Would it be permissible to strip away the SER jacket and continue the constituent XHHW-2 wires underground in a raceway?

I believe a few code cycles ago, it wasnt specifically stated that SE cable could not be used below grade and that wording is relatively new. I have always assumed that the issue is the bare EGC.
In general, can a bare aluminum EGC be used below grade?

Up thru 2005, yes. That changed in 2008- it's allowed only if it was existing, must have the egc for new sp's.

but note that is for feeders between different structures. Separate N/G has been required for same-building sub panels for a long time.

so there is not a bare conductor with two insulated conductors? wrapped in a gray sheath?

That is SEU.

electrofelon · May 15, 2016

Carultch said:
I think I let one of my designs slip through the cracks with SER spec'd in an installation that is mostly above ground, and part of it had a 10 ft "dive" below ground

I used SER in pipe below ground (about 10 feet) back in 2007. I think that is before the wording was changed, at least that is my excuse :angel:. It still haunts me every day.

tkb · May 15, 2016

JFletcher said:
Werent subpanels permitted to be fed from 3 conductor cable in the past?

Yes, but that was only allowed if there wasn't any parallel ground paths like a water pipe, phone wire or cable tv.

user 100 · May 16, 2016

electrofelon said:
but note that is for feeders between different structures. Separate N/G has been required for same-building sub panels for a long time.

There was a thread about this recently- looked this up then and found no evidence 3 wire to sub in same structure was ever permitted or at least it wasn't enforced in many areas.

ActionDave · May 16, 2016

electrofelon said:
In general, can a bare aluminum EGC be used below grade? ....

No

250.120 Equipment Grounding Conductor Installation

(B) Aluminum and Copper-Clad Aluminum Conductors.
Equipment grounding conductors of bare or insulated alumi-
num or copper-clad aluminum shall be permitted. Bare con-
ductors shall not come in direct contact with masonry or the
earth or where subject to corrosive conditions. Aluminum or
copper-clad aluminum conductors shall not be terminated
within 450 mm (18 in.) of the earth.

Click to expand...

ActionDave · May 16, 2016

enireh said:
in the past three conductors was permitted to feed sub panel, now all are required to have a four wire feed yes?

Yes

user 100 said:
Up thru 2005, yes. That changed in 2008....

Yup

tkb said:
Yes, but that was only allowed if there wasn't any parallel ground paths like a water pipe, phone wire or cable tv.

Correct

electrofelon said:
...but note that is for feeders between different structures. Separate N/G has been required for same-building sub panels for a long time..

user 100 said:
There was a thread about this recently- looked this up then and found no evidence 3 wire to sub in same structure was ever permitted or at least it wasn't enforced in many areas.

:thumbsup::thumbsup:

Smart $ · May 16, 2016

electrofelon said:
I used SER in pipe below ground (about 10 feet) back in 2007. I think that is before the wording was changed, at least that is my excuse :angel:. It still haunts me every day.

338.12 [Uses Not Permitted] was added in 2008. The reason for not using SE underground prior to 2008 did not exist. :angel:

electrofelon · May 16, 2016

Smart $ said:
338.12 [Uses Not Permitted] was added in 2008. The reason for not using SE underground prior to 2008 did not exist. :angel:

Oh grand, it is true and I didnt just subconsciously make that up!

250.120 Equipment Grounding Conductor Installation

(B) Aluminum and Copper-Clad Aluminum Conductors.
Equipment grounding conductors of bare or insulated alumi-
num or copper-clad aluminum shall be permitted. Bare con-
ductors shall not come in direct contact with masonry or the
earth or where subject to corrosive conditions. Aluminum or
copper-clad aluminum conductors shall not be terminated
within 450 mm (18 in.) of the earth.

I was pretty sure that was the case but was too lazy to double check. So back to the SER, It seems that as Carultch was proposing, if one really wanted to get one up on the man and/or cause trouble, he or she could re-identify one of the insulated conductors as the EGC, and get away with using it in pipe below grade? (looking for the devil smiley, alas guess it doesnt exist....)

Smart $ · May 16, 2016

electrofelon said:
Oh grand, it is true and I didnt just subconsciously make that up!

I was pretty sure that was the case but was too lazy to double check. So back to the SER, It seems that as Carultch was proposing, if one really wanted to get one up on the man and/or cause trouble, he or she could re-identify one of the insulated conductors as the EGC, and get away with using it in pipe below grade? (looking for the devil smiley, alas guess it doesn't exist....)

Sort of moot point to discuss, not being able to use underground now and all, eh?

rippledipple · May 16, 2016

se

se

electrofelon said:
Oh grand, it is true and I didnt just subconsciously make that up!

I was pretty sure that was the case but was too lazy to double check. So back to the SER, It seems that as Carultch was proposing, if one really wanted to get one up on the man and/or cause trouble, he or she could re-identify one of the insulated conductors as the EGC, and get away with using it in pipe below grade? (looking for the devil smiley, alas guess it doesnt exist....)

I think because it was design for free air, like uf can't go in pipe!

infinity · May 16, 2016

rippledipple said:
I think because it was design for free air, like uf can't go in pipe!

UF cannot get installed in a properly size raceway?

electrofelon · May 16, 2016

Smart $ said:
Sort of moot point to discuss, not being able to use underground now and all, eh?

If it has marked XHHW inners and I don't have a bare egc, than it seems plausible that then it's just XHHW conductors in conduit with some superfluous gray sheath.

enireh · May 16, 2016

wire

user 100 said:
Up thru 2005, yes. That changed in 2008- it's allowed only if it was existing, must have the egc for new sp's.

where is that in the code book? I need to show this to the home inspector and thank you

electrofelon · May 16, 2016

enireh said:
where is that in the code book? I need to show this to the home inspector and thank you

look at 250.32(B) and 250.142

electricguy61 · May 16, 2016

Would any conscientious contractor propose to leave a bare aluminum wire in a conduit, even if it was covered by a sheath? I would give it less then a year before it failed.

enireh · May 16, 2016

wire

thank you much!

Carultch · May 16, 2016

electrofelon said:
Oh grand, it is true and I didnt just subconsciously make that up!

I was pretty sure that was the case but was too lazy to double check. So back to the SER, It seems that as Carultch was proposing, if one really wanted to get one up on the man and/or cause trouble, he or she could re-identify one of the insulated conductors as the EGC, and get away with using it in pipe below grade? (looking for the devil smiley, alas guess it doesnt exist....)

OK, so that sort of covers the restriction on aluminum SE cable direct buried, even though the plastic jacket makes it no longer truly bare. But it doesn't cover the reason why copper SE cable couldn't be used underground. Or even any SE cable inside a raceway.

As I understand it, you can still run a bare EGC with individual conductors inside a raceway, even if that raceway goes underground, provided that it terminates at least the required distance above grade. Not a practice I recommend, because of bare EGC and abrasion of the remaining wires, but I don't see a rule why it can't be done. And if it can be done, then we still haven't explained why SE cable cannot be underground in a raceway.

Smart $ · May 16, 2016

electrofelon said:
If it has marked XHHW inners and I don't have a bare egc, than it seems plausible that then it's just XHHW conductors in conduit with some superfluous gray sheath.

Doesn't change the fact it is SE cable and not permitted underground, does it?

If it's innards are marked XHHW, you can strip off that superfluous gray sheath to be compatible... :happyyes:

wire

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