Conduit heating up

[-=PEAKABOO=-]

What are the most common things that you guys have seen that make conduits (EMT) heat up????
Just curious

[Smart $]

What are the most common things that you guys have seen that make conduits (EMT) heat up????
Just curious
Heavily loaded conductors.

How warm (or hot) are we talking?

[LarryFine]

Splitting circuit conductors.

[frenchelectrican]

Improper phasing wires in conduits like all one phase on one conduit and second phase on other conduits etc etc that will result " induction " effect and i heard somestory [ i am not sure if that is the fact or not ] that the conducit in inproper phasing cause the conduits get very hot like heating element and also can induct the werid noise as well.

Merci , Marc

[macmikeman]

And I have seen some hot conduits that had just way way too many conductors pulled in. Usually found in state run buildings by the way. Circuits just keep getting added to the few runs of existing conduit rather than new runs added. Must be the budget thing....

[Greg Swartz]

Improper phasing wires in conduits like all one phase on one conduit and second phase on other conduits etc etc that will result " induction " effect and i heard somestory [ i am not sure if that is the fact or not ] that the conducit in inproper phasing cause the conduits get very hot like heating element and also can induct the werid noise as well.

Merci , Marc

That's what I was going to say. This only happens when you put more than 3 same phase conductors in a conduit though. (Derating and such)

We had a 33 story hi-rise that someone did this in... Well, ever see a transformer that size blow?

When they fired the super, the PM, several of the foremen, a friend of mine got to pull the wire out. It was 9 hours after the transformer blew, and the wire was still so hot that the insulation was melting in the crew's gloves as they were trying to pull the wire out!

[ghostbuster]

40-50 AMPS of illiegal neutral/ground current via the conduit heats up real good.We had one customer using the 400 amp disconnect enclosure doing the same trick.(conducting current) He had a large fan blowing on it to keep it cool.He was quite proud of himself.:)

[Jeff Weissman Electric]

What are the most common things that you guys have seen that make conduits (EMT) heat up????
Just curious
Hear in Texas its the sun!
years ago I got a call from A HO saying his yard man touched the breaker panel and almost burned his hands. I rushed over and I found it outside, facing south, 4:00 pm first of August. I almost burned my hands opening the cover.

[kc8dxx]

One industrial customer of ours failed to follow our installation instructions, and wired each phase in separate conduits. The conduit got so hot it sagged rather dramatically. The failure mode was that the next morning after the test, someone walked into the room and hit their head on the overhead (now head-level) conduit.

The list of NEC no-no's on that installation was rather large. Improper phasing of wires in a conduit. Improper securing of conduit. Improper routing of EGC's.

[ashtrak]

Could someone tell me why so many areas have their panels mounted outside the dwelling.It seems to be more of a Central US and West Coast thing. I'm on the East Coast. I've never seen or installed a service outside a dwelling.....

[Sierrasparky]

Could someone tell me why so many areas have their panels mounted outside the dwelling.It seems to be more of a Central US and West Coast thing. I'm on the East Coast. I've never seen or installed a service outside a dwelling.....

I believe it's possibly due to the climate.and the utility wanting control over the service. If the service is in the house how can they gain access to read the meter or check for theft.In Los Angeles the POCO had request the meter to be viewable from the neighbors yard to read with scope. Meter readers carried a scope to read many meters from one place Meters in southern Ca in the old days were located inside in some areas. Also most houses in west don't have basements or equipment rooms. Now that meters are readable remotely I don't see them moving inside due to lack of access by the Utility

[tshea]

What are the most common things that you guys have seen that make conduits (EMT) heat up????
Just curious

FIRE will do it everytime!

[tshea]

Could someone tell me why so many areas have their panels mounted outside the dwelling.It seems to be more of a Central US and West Coast thing. I'm on the East Coast. I've never seen or installed a service outside a dwelling.....

When I was in NC, on the coast, most of the panels were outdoors due to no baseemnt or utility room.

[Jeff Weissman Electric]

Could someone tell me why so many areas have their panels mounted outside the dwelling.It seems to be more of a Central US and West Coast thing. I'm on the East Coast. I've never seen or installed a service outside a dwelling.....

FWIW it's a POCO & AHJ thing
one municipality here wants, if the panel(s) is inside there must be a main disc outside. I think the firedepartment wants to be ablwe to cut power?
Some don't but all meters must be outside & now accessible with out entering the back yard.
And another is down here no one has ever installed SE cable or PVC from meter to the Weather head.
The first time I was up east & saw SE for the first time, I asked where you get Romex that big?

[bigjohn67]

Common Causes:
1. Overheated conductors ( To many in pipe)
2. Lost Neutral and conduit used as ground becomes neutral
3. Conduit becomes neutral and has loose connectors and couplings

Plane and simple.

[Greg Swartz]

40-50 AMPS of illiegal neutral/ground current via the conduit heats up real good.We had one customer using the 400 amp disconnect enclosure doing the same trick.(conducting current) He had a large fan blowing on it to keep it cool.He was quite proud of himself.:)

Here's your card!

[quogueelectric]

What are the most common things that you guys have seen that make conduits (EMT) heat up????
Just curious
Improper wiring and heavy loads with an honorable mention to building harmonics. all conductors on a multiwire branch ckt must follow each other to thier destination including the neutral AND the ground up to thier branch separation point. Check for propper wiring especially people who dont know how to properly run multiwire ckts and how to properly twin breakers like a 3 wire ckt with both red and black on the same twin breaker. 20 out black 20 out red and 40 back on the white when twinned improperly.

[iwire]

How warm (or hot) are we talking?

I still have not seen an answer to this question.

An entirely NEC compliant conduit run can run pretty warm.

[-=PEAKABOO=-]

I still have not seen an answer to this question.

An entirely NEC compliant conduit run can run pretty warm.


I have not measured it but hot to the touch. You can hold the conduit but it is pretty warm when doing this. These are long runs of #12 (over 150' with about 7 amps of continuous current. I think this is the problem myself. The neutrals all seam to be fairly balanced.

[Pierre C Belarge]

As Bob was alluding to, a large load can create quite a warm raceway and this would generally not be an issue.

[ptonsparky]

I have followed up on ECs who were low bid and have found conduits that added to the A/C load. They were filled to the max and loaded to the max but code min compliant. Using HID rated breakers seems to help with those max loaded CBs that eventually start tripping due to heat.

[memyselfandI]

What are the most common things that you guys have seen that make conduits (EMT) heat up????
Just curious


heavy loads, ambient air temperatures, sunlight...

[peter d]

The best I ever saw was a 2.5" EMT completely packed with #10's.

It ran about 50' from the electric room panel down to a trough (missing the cover) on the sales floor where the branch circuits split off.

I'm sure they derated all those conductors. ;)

[boboelectric]

H.I.D. lighting circuits. I had a few calls in office buildings where office people thought transformers felt too hot. 150 c rating.

[danickstr]

a thhn run could go to 190 degrees F and still be code compliant.

The connectors would have to stay below 167 F though.

But that sure seems hot to me.

[LarryFine]

a thhn run could go to 190 degrees F and still be code compliant.194, actually. :)

F - 32 / 9 * 5 = C

C / 5 * 9 + 32 = F