Using existing steam piping as conduit.

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MIEngineer

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Hello all,

Thank you for taking the time to look over my question. We have a site that is currently heated by steam, with heaters around the building. We would like to replace the steam heaters with electric heat. I am wondering if I could use the existing 1" or so steam piping as conduit for the new electrical feeds (assuming the size of the pipe is correct). The walls and ceiling are very crowded making new installation difficult.

I have a feeling this wouldn't be allowed since the pipe isn't "listed" to contain electrical conductors but I wasn't sure of any exact references.

Thank you.
 
You are right; it's not allowed. The NEC has several chapters that describe wiring methods and raceway types. Steam pipe is not included as an approved raceway. Besides, it would not be a smart choice. The inside surfaces of a steam pipe are likely to be very rough. Attempting to pull conductors along such surfaced would damage the insulation.

Welcome to the Forum.
 
When Edison Illuminating Company first started installing electrical systems in businesses and homes in NYC, it would be a common practice to evacuate the gas piping already installed to and in the building and reuse them as electrical conduits. From what I understand, there are still several buildings in the city with electrical wiring in old gas pipes.
 
charlie b said:
I'm not sure I know what that would mean. Can you elaborate?
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Say the old pipe ran across an inaccessible plaster ceiling in an old building. You could cut it off at both accessible ends and use it as a sleeve to pull say an MC cable from one side to the other.


Regarding old gas piping in buildings, as Bryan mentioned some of the old gas pipe was converted to electrical piping as electricity usage became more widespread after the turn of the last century. There are still some old buildings and houses around here that have active 3/8" black gas piping once used for gas lights. For the most part they've been capped off where they enter a room but some are still connected to a natural gas system. Some very old houses will even have fixtures hung from the old gas pipe with a fixture hickey and a piece of old BX stubbed out next to the pipe providing the power.
 
I wouldn?t be as concerned with gas piping. But over a long period of time, any liquid flowing through a pipe, or steam flowing through a pipe, will cause erosion of the inner walls. The degree to which that process would create rough surfaces (i.e., that might damage insulation of a cable being pulled through the pipe) would depend on many factors (e.g., time, temperature, flow rate, chemical composition of the fluid, and chemical composition of the pipe).
 
I agree with Trevor, I see no reason why you couldn't "fish" a "cable assembly" through these old pipes.

Roger
 
roger said:
I agree with Trevor, I see no reason why you couldn't "fish" a "cable assembly" through these old pipes.

Roger
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I agree that you could fish a suitable cable assembly through _straight_ _sections_ of these old pipes, but I would not try to fish past any elbows. Plumbing elbows don't have much radius, and there is probably less design to prevent sharp edges that could cut into materials being 'fished'.

-Jon
 
winnie said:
I agree that you could fish a suitable cable assembly through _straight_ _sections_ of these old pipes, but I would not try to fish past any elbows. Plumbing elbows don't have much radius, and there is probably less design to prevent sharp edges that could cut into materials being 'fished'.
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Agreed, especially because it is very likely that the cut pipe ends were never reamed.
 
bphgravity said:
When Edison Illuminating Company first started installing electrical systems in businesses and homes in NYC, it would be a common practice to evacuate the gas piping already installed to and in the building and reuse them as electrical conduits. From what I understand, there are still several buildings in the city with electrical wiring in old gas pipes.
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I've seen my fair share of old buildings in various stages of rehab, never have I seen old gas piping reused as an electrical condiut or raceway. The original retrofit method of choice was to snake a BX to the existing gas nipple, and install a pancake box using the gas nipple as support, and to house the electrical connections.

In most single family homes, brownstones and the typical 6-family houses of the outer boroughs, the 3/8 gas lighting pipes had no means of valving off the lighting branches from the appliance risers. So in order to continue feeding apartment stoves, the entire systems were usually entirely pressurized. There was no mistaking the odor when entering a gas building.

Over time the original inferior gas lines began to corrode and develop pinhole leaks, and the retrofitted electric became outdated. Until that time, it was not uncommon for most multi-family apartment buildings to have one electric and one gas meter.
 
There is a replica Castle in Dedham MA,

Castle%20and%20Green%20Field.jpg


it was built in the late 1800s and it had gas lighting, at some point the gas lights where retro-fitted with electricity.

I had my first real paying job working in it (dishwasher) and later I had my first wedding in it.

Anyway somehow..I can't figure out how... a single conductor was fished inside the gas line. That was the 'hot', the gas line itself was the grounded conductor.

This is a great surprise when pulling down these retro fitted gas wall sconces.
 
You think that's a suprise? How about the Bronx neutrals we used to find? This is when a formerly 20a 120v apartment fuse panel, (looked more like glorified 44 11/16 box with hinged cover) with 2 15a fuses suddenly becomes a 20a 220v 2/4 fuse panel without the hassle or expense of having to install another ungrounded conductor back to the service.
 
winnie said:
I agree that you could fish a suitable cable assembly through _straight_ _sections_ of these old pipes, but I would not try to fish past any elbows. Plumbing elbows don't have much radius, and there is probably less design to prevent sharp edges that could cut into materials being 'fished'.
-Jon
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That was my thought, as well. Plumbing elbows will probably violate bending radius rules.
 
Actually, if anybody could fish a cable assembly past plumbing 90's I say more power to them. :wink:

As far as the pipe not being reamed, cable assemblies are drug across sharp edges on an every day basis, and if a metallic cable assembly is used, it's a non-issue anyways.


Roger
 
roger said:
Actually, if anybody could fish a cable assembly past plumbing 90's I say more power to them. :wink:

As far as the pipe not being reamed, cable assemblies are drug across sharp edges on an every day basis, and if a metallic cable assembly is used, it's a non-issue anyways.


Roger
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don't ask me why i know this but if you do need to use rmc and associated fittings together with this steam piping it is very likely to have a very different inside diameter causing electrician to say many different combinations of bad words over an extended period of time during said fishing process.
 
aja21 said:
don't ask me why i know this but if you do need to use rmc and associated fittings together with this steam piping it is very likely to have a very different inside diameter causing electrician to say many different combinations of bad words over an extended period of time during said fishing process.
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I thought that was standard proceedure for many tasks. If it gets to hard, we bring out a tugger. :grin:

Roger
 
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