Correct breaker box for heat pump.

[Azmp1]

Hey folks, so I just ran the new 60amp service outside for the upcoming heat pump. Just picked up this box and its confusing the heck out of me.
It's cutler hammer (eaton) 125 amp 4 spaces/8 circuits outdoor main lug. It's a 110/240 box, but in the specs it says single phase/single pole.... By the look of it I does have both phase terminals and a single ground/neutral bar which should be fine. I'm not an electrician, but have no problems with electrical work, is isn't my first time running sub panels, but this box is just confusing me, well, description is anyway.
Here's the pic

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[greg.stevenson.90]

Yes that's single phase. It's how the power comes from the transformer how it gets the name single phase or three phase. That is clearly single phase. You are gonna need a ground bar. The one in there needs to remain isolated from the can. It is your neutral bar. You need 4 wires running out to this panel.

 

[jblizzle]

Looks like Greg hit the points I was going to make

You have to isolate the ground which required another bus bar.

 

[Azmp1]

Ah... Ok. That makes sense now I suppose. I've never dealt with this type of the box before, few sub boxes that I ran before were not single phase.
The cable I'm running to this box is a 6-3, so it is a 4 wire cable. As far as the ground bar, so I can just buy a separate ground bar and attach it in the box?

Thank you guys!


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[Azmp1]

Got everything finished up and ready to go for the heat pump (still need to ground the box). I think this is correct, but for the sake of double checking.... Does this look right to you guys?

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[greg.stevenson.90]

Looks good. Ofcourse someone would say you aren't supposed to put Romex in pvc, but as long as it's not buried pvc, (where water gets in it, because it does and will) then it looks good.

 

[Azmp1]

Thank you Greg. About the Romex... yes I know it's an unshielded cable intended for an interior use, but I did not know that I couldn't run it inside the PVC. What would be the difference of just running 4 separate wires inside the PVC, or running the Romex which is pretty much the same thing, but in the thin plastic wrap?


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[greg.stevenson.90]

It's about heating up. Is job being inspected? If it was my own house, n not inspected, then it's fine. It's kinda just a technicality. But the theory is the Romex is rated for heat then inside pipe it could get hotter. People run Romex in pipe all the time, I wouldn't lose sleep over it.

 

[greg.stevenson.90]

By the way, different areas have different enforced rules, so this may not even be a real issue anyhow.

 

[yostmatt]

I ran mine the same way from my house to shed, about 25 feet in the same conduit. When it got inspected the inspector did not ding me for it. He was more worried my GFI was wired correctly.

 

[Azmp1]

Thanks for the explanation Greg. Learned something new today, I had no idea about the heat rating. As far as inspection, I'm doing the pump install, including the service run myself, so no worries there.
And Matt, you just jogged my memory about the inspection as well... The electrical to my equipment that was ran by the builder was ran from my subpanel that I've installed years ago that we were gonna use for the hot tob that never happened. That was also a 60 amp service that we ended up using for variety of other things outside and I ran it exactly same way with 6-3 Romex in the PVC. Inspector did look and asked about that subpanel and we told him that it was an old job, he didn't say anything else.


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[danpik]

Actually, any conduit outdoors, above ground or buried, is rated as a wet location and the wire inside has to be rated for wet use (thwn). Unless it is a service rated cable assembly (SER) or individual THWN wires it can not be in a wet location. SER cable, if used inside conduit, needs to be de-rated due to possible overheating
Also, Since this sub-panel can be considered a separate structure, per the NEC it should have a ground rod driven. EDIT...Just looked at the picture again. If it is mounted on the structure the main panel is located in then you do not need an additional rod.

My local inspector would look for a gasket seal on the top entrance opening and have us seal all unused holes on the back of the panel. Also needs a knockout cover in the bottom opening.

Everything else looks good.

I am curious. You made this comment in an earlier post... I've never dealt with this type of the box before, few sub boxes that I ran before were not single phase. If you are familiar with 3 phase boxes, you should have a good understanding of single phase. Or am I missing something here.

 

[Azmp1]

Hey Dan, so... quite obviously I don't know this as well as I thought I did.... Need to hit the books again. Smh.
Yes I'm still planning to ground the box to the existing ground rod that was driven for the pool equipment electrical. The structure the sub panel is mounted on is a detached pool shed, so yes it will definitely be grounded. I also always seal anything on the exterior using the duct seal putty just didn't get there yet.

I bit more on the Romex... So #6 awg Romex nm-b is rated for 55amps with a temp rating of 90 degrees C. This is the exact same temp rating for the THHWN wire. So I'm curious... What's the overheating concern? Is it the fact that Romex has that extra layer of the insulation? If so, stripping the insulation should alleviate the problem? The insulation on the wires themselves looks pretty much the same on either wire.


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[JasonLion]

You should be careful about "logical reasoning" when dealing with electrical stuff. There are logical reasons for things, but that is not directly connected to the code requirements. You generally have to meet the code requirements even when they don't make sense. Removing the insulation may solve the actual logical issue, but is almost certainly not going to meet code.

Actually, I can't quite tell if you meet code or not. Romex gets derated in that context, but may still be sufficient depending on wire size, run length, breaker size, etc.

 

[Azmp1]

I certainly agree Jason. Really, just trying to see what the actual difference is between the cables.
Strictly from amp load and derating perspective I think im ok. Total half length is around 120' with amp load spec on the heater im looking at is 42amp.

So, im digging into NEC... senction 312.5 C. interesting situation here. This wouldn't apply to me as my conduit is more then 3 meter anyway, but still according to this, Sleeved cable is allowed in the conduit if the panel is surface mounted and the sleeve is extended into enclosure? Maybe im misunderstanding.

from 312.5

(C) Cables. Where cable is used, each cable shall be secured
to the cabinet, cutout box, or meter socket enclosure.
Exception: Cables with entirely nonmetallic sheaths shall
be permitted to enter the top of a surface-mounted enclosure
through one or more nonflexible raceways not less
than 450 mm (18 in.) and not more than 3.0 m (10 ft) in
length, provided all of the following conditions are met:
(a) Each cable is fastened within 300 mm (12 in.),
measured along the sheath, of the outer end of the raceway.
(b) The raceway extends directly above the enclosure
and does not penetrate a structural ceiling.
(c) A fitting is provided on each end of the raceway to
protect the cable(s) from abrasion and the fittings remain
accessible after installation.
(d) The raceway is sealed or plugged at the outer end
using approved means so as to prevent access to the enclosure
through the raceway.
(e) The cable sheath is continuous through the raceway
and extends into the enclosure beyond the fitting not
less than 6 mm (1#8260;4 in.).
(f) The raceway is fastened at its outer end and at
other points in accordance with the applicable article.
(g) Where installed as conduit or tubing, the allowable
cable fill does not exceed that permitted for complete conduit
or tubing systems by Table 1 of Chapter 9 of this Code
and all applicable notes thereto

 

[danpik]

AZMP1
NM-B can not be used outdoors or in any wet location. It is not rated for that use. The sheathing on the cable, if it is used in conduit, can cause it to have to be de-rated. I never used romex in conduit so I would have to spend some time in the NEC book to figure the de-rating, If it is needed. Stripping the sheathing off will not gain you anything as far as codes go as the wires inside the cable are mot marked/identified as the NEC requires.

The insulation may look the same but, that is where the problems stem from some times. THWN wire (Thermoplastic Heat and Water-resistant Nylon-coated) is labeled as such so the user and subsequent users know what it is. Wires in a NM-b cable may, and most times are THWN wires but without the designation printed on them nobody can be sure of it.

As soon as my broken wrist heals I have to go fix a job someone did several years ago. They buried two separate NM-b 12-2 cables inside a 3/4" conduit. (code violation on both the NM-B and two separate circuits to an out building) Both cables are shorting to ground and tripping the panel mounted GFCI. When I pulled the LB cover off at the small shed (about 6' lower than the garage where the run starts) it was full to the top with water. I suspect that the cables may have been compromised one of two ways. Either the water deteriorated the cable housing or they pulled the cable thru as they were gluing the sections and the PVC glue dripped onto the cable and ate away the plastic jacket. Or it is a combination of the two.

Jason said this... You generally have to meet the code requirements even when they don't make sense this is what trips up a lot of people. Once you understand the reasoning behind why the codes exist they then make sense.

 

[Azmp1]

Thank you for the detailed insight Dan. I should just shut up and stop trying to make sense of this and dig into NEC. One thing i'll tell you, I have an old 60amp run that I did over 10 years ago using conduited romex and it has no issues, that was the sub panel the pool electrical was run from and the inspector passed it. of course not to say that it may not start in the future. Maybe one day, I will pull the wiring and replace with THHWN.
In any case thank you folks on all the insight on this!

 

[danpik]

I certainly agree Jason. Really, just trying to see what the actual difference is between the cables.
Strictly from amp load and derating perspective I think im ok. Total half length is around 120' with amp load spec on the heater im looking at is 42amp.

The de-rating, if needed, would apply to supplied rating of the box, not the current load on the box. For example,if the supply was a 60 amp breaker then that is what you would de-rate from, not the 42 amp load of the heater

So, im digging into NEC... senction 312.5 C. interesting situation here. This wouldn't apply to me as my conduit is more then 3 meter anyway, but still according to this, Sleeved cable is allowed in the conduit if the panel is surface mounted and the sleeve is extended into enclosure? Maybe im misunderstanding.

An example of this is in my basement. I have a couple of switches and receptacles mounted on the block walls. The romex feeding these is sleeved in conduit from the ceiling area. Perfectly legal as long as all of the code requirements below are met.
(a) is met as the cable is stapled about 6" before it enters the conduit
(b) is met as it is into the open rafter bay.
(c)and (d) are met as there is a cable clamp on the conduit.
(e) is met as there is one continuous cable in there.
(f) is met as there is a clamp both at the midway point and the end of the conduit fastening it to the wall.
(g) is good as it is one 14-2 cable inside a 1/2" conduit

from 312.5

(C) Cables. Where cable is used, each cable shall be secured
to the cabinet, cutout box, or meter socket enclosure.
Exception: Cables with entirely nonmetallic sheaths shall
be permitted to enter the top of a surface-mounted enclosure
through one or more nonflexible raceways not less
than 450 mm (18 in.) and not more than 3.0 m (10 ft) in
length, provided all of the following conditions are met:
(a) Each cable is fastened within 300 mm (12 in.),
measured along the sheath, of the outer end of the raceway.
(b) The raceway extends directly above the enclosure
and does not penetrate a structural ceiling.
(c) A fitting is provided on each end of the raceway to
protect the cable(s) from abrasion and the fittings remain
accessible after installation.
(d) The raceway is sealed or plugged at the outer end
using approved means so as to prevent access to the enclosure
through the raceway.
(e) The cable sheath is continuous through the raceway
and extends into the enclosure beyond the fitting not
less than 6 mm (1#8260;4 in.).
(f) The raceway is fastened at its outer end and at
other points in accordance with the applicable article.
(g) Where installed as conduit or tubing, the allowable
cable fill does not exceed that permitted for complete conduit
or tubing systems by Table 1 of Chapter 9 of this Code
and all applicable notes thereto

 

[danpik]

I should just shut up and stop trying to make sense of this and dig into NEC.

You don't have to do that, intelligent conversation is how we all learn. I had to learn all of this years ago and maybe someday you can pass it on as well.

One thing i'll tell you, I have an old 60amp run that I did over 10 years ago using conduited romex and it has no issues, that was the sub panel the pool electrical was run from and the inspector passed it. of course not to say that it may not start in the future. Maybe one day, I will pull the wiring and replace with THHWN.
In any case thank you folks on all the insight on this!

If this was all indoors then it is up to how the inspector interprets the codes. I have seen several installations that way over the years and none of them had any problems. In fact the only one I ever saw with a problem was in a house that was being sold and an overzealous home inspector called it out. He missed about 3 glaring electrical issues that any first year electrical student should have seen, but fixated on a romex cable going between a main and sub in a conduit.

 

[Azmp1]

You don't have to do that, intelligent conversation is how we all learn. I had to learn all of this years ago and maybe someday you can pass it on as well.

Very true. One of the reasons I love this forum, is that for the most part discussions are serious, mature and on point, as you don't have some 17 year old trying to flame you for asking a question as on some of the other forums I post on.

Thank you again for the information.