480V passing through 120V panel

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SegAtari

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Just like the title says;

I've recently taken over as the Maintenance Manager for an industrial plant (shall remain nameless) and I've been having all kinds of fun fixing and rewiring numerous machines on the shop floor. The previous holder of this job was apparently more of a DIY electrical guru and it shows in some of the rework I've had to do.

But my main question concerns one particular press brake I have that is wired for 3ph 480V. I've traced the conduit back through the overhead and it ends up going to a 120V panel! Pulled the cover off to continue tracing it out and discover it's using the 120V panel as a pass-through junction box basically. There is a 3/4 conduit run coming out the side of the 120 going over to the adjacent 480 panel sitting 2 feet away. This guy wired the 480 and I guess used a spare conduit run he had coming from the first panel and then just made a jump across to get to the breaker he needed.

It seems lazy as hell to me but I know Article 300.3 (C) allows for multiple conductors of different voltages to share the same conduit enclosure, but is does that also apply to electrical panels as well?
My gut tells me this is wrong and needs to be changed, but my boss is going to want to see specific coding before I convince him to let me rework this.
 
As DRGREG pointed out 312.8 addresses conductors that feed through a cabinet that houses a panelboard.

312.8 Switch and Overcurrent Device Enclosures. The wiring
space within enclosures for switches and overcurrent devices
shall be permitted for other wiring and equipment subject to
limitations for specific equipment as provided in (A) and (B).
(A) Splices, Taps, and Feed-Through Conductors. The wiring
space of enclosures for switches or overcurrent devices shall be
permitted for conductors feeding through, spliced, or tapping
off to other enclosures, switches, or overcurrent devices where
all of the following conditions are met:
(1) The total of all conductors installed at any cross section of
the wiring space does not exceed 40 percent of the crosssectional
area of that space.
(2) The total area of all conductors, splices, and taps installed
at any cross section of the wiring space does not exceed
75 percent of the cross-sectional area of that space.
(3) A warning label complying with 110.21(B) is applied to
the enclosure that identifies the closest disconnecting
means for any feed-through conductors.
Click to expand...

Chris
 
One other thing to watch out for is that if in that lighting panel (more likely 240V), if there are any low voltage lighting control devices like RR relays and such, the Low Voltage control /signal wiring may not be rated for 600V, so the presence of 480V conductors makes them a violation.
 
Thanks for the responses!

Thanks for the responses!

First off, thank you to those who responded and helped point me in the right direction for this issue. Good help and advice is always appreciated.:)

I verified that the lower panel is indeed strictly a 120V service. Its mainly used to provide power to some various smaller machinery in one of our shop spaces (pedestal grinders and the like) and is simply being used as a pass-through in the case of this lone 480V service.
I gave the boss-man all the info I had and our options and my recommendation that we separate the panels and reroute the 480V service. It took him a couple hours but he finally decided to just go with that suggestion after all.

My thanks once again to the responses here as they helped point me in the right direction to make my case.
 
SegAtari said:
I verified that the lower panel is indeed strictly a 120V service. Its mainly used to provide power to some various smaller machinery in one of our shop spaces (pedestal grinders and the like) and is simply being used as a pass-through in the case of this lone 480V service.
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A 120V only panel is rather rare. I still would have guessed a 120/208V or 120/240V panel. 208Y/120V would have been the most efficient.

Even if all the circuits are fed from single pole breakers in this panel, it is still not a 120V panel.

The feeder and OCPD that powers this panel would be the determining factor.
 
Service?

Service?

Are they service or sub panels? Service conductors aren't allowed to be in a common raceway or enclosure with anything else unless it is in the panel or gear to be served. I've never seen a 120V service. Just curious. Not trying to be an ass FYI
 
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I'm still playing the odds that it's actually a 120/2XX panel with all 120 V loads. But I'm also still waiting to hear if it's okay or not as further details come out.

It's probably a bad thing that I wouldn't be so looking for something to do that I'm trying to change it out when it's been fine for years. too. :? :blink: :huh:
 
MAC702 said:
I'm still playing the odds that it's actually a 120/2XX panel with all 120 V loads. But I'm also still waiting to hear if it's okay or not as further details come out.

It's probably a bad thing that I wouldn't be so looking for something to do that I'm trying to change it out when it's been fine for years. too. :? :blink: :huh:
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Actually what voltage or voltages are present in the panel is not that important as long as 300.3(C) and posts 2, 3, and 4 are met.

Take note of 312.8(A)(3) that addresses your concern.

Roger
 
MAC702 said:
I'm still playing the odds that it's actually a 120/2XX panel with all 120 V loads. But I'm also still waiting to hear if it's okay or not as further details come out.

It's probably a bad thing that I wouldn't be so looking for something to do that I'm trying to change it out when it's been fine for years. too. :? :blink: :huh:
Click to expand...

There is no problem with 480V and 240V in the same pipe or enclosure, it's done all the time.
 
MAC702 said:
Yes, but will more depend on Code at the time of installation. My 2008 Handbook here at home only has a 312.8, with no subsections, but does include the basic fill calculation.
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I agree, the section was changed in 2011 but a set of conductors passing through an enclosure would be a red flag.

Roger
 
120 panels do come about in industrial do come up at times. The first one that comes to mind at our plant would ber a small 6 space panel for our check weighers, we needed a small isolation transformer and used a 120 volt and jumped line 1 to line 2 feed, so the panel was all the same 120.

Steve
 
Just pull the 480 out and pipe around, 2 box/covers, 10' rig, etc., unless you have to ask unlike the guy who had the job before you.
 
sameguy said:
Just pull the 480 out and pipe around, 2 box/covers, 10' rig, etc., unless you have to ask unlike the guy who had the job before you.
Click to expand...

Assuming it's okay with the guy that owns the machine that's down while this is being done and he doesn't have more important things for his electrician to be doing than fixing something that isn't broken.
 
Though most wouldn't ordinarily do it, one could run the 480 volt supply conductors through the "secondary panel" and run both primary and secondary conductors through same raceway between transformer and secondary panel.

As I said most wouldn't ordinarily do so, but occasionally there may be some limitation that makes that option more desirable.
 
sblk55 said:
120 panels do come about in industrial do come up at times. The first one that comes to mind at our plant would ber a small 6 space panel for our check weighers, we needed a small isolation transformer and used a 120 volt and jumped line 1 to line 2 feed, so the panel was all the same 120.

Steve
Click to expand...

I’m pretty sure that is still a 120/240 volt panel. I remember some 120v fuse panels that were used for services, but I don’t think I have ever really seen a 120v breaker panel.
 
sblk55 said:
120 panels do come about in industrial do come up at times. The first one that comes to mind at our plant would ber a small 6 space panel for our check weighers, we needed a small isolation transformer and used a 120 volt and jumped line 1 to line 2 feed, so the panel was all the same 120.

Steve
Click to expand...
The panel could be rated 480 or even 600 volts, but if you supply it with 120 volts most are going to call it a 120 volt panel.

Similar goes for a 125 amp rated panel but only supplied by say a 50 amp feeder circuit - most are going to call that a 50 amp panel per it's actual use.
 
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