Should NM wiring be recommended?

Raghav Singh · 10-27-2011, 09:02 PM

Hi,
Would you recommend that this cable going into the furnace be replaced by romex, or is the armored cable fine as is? Thanks .

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**Jim Luttrall** · 10-27-2011, 09:57 PM

I could be wrong but that sure looks like a flexible gas connector, not armored cable.

AC would be preferred over NM if properly installed.

Raghav Singh · 10-27-2011, 10:42 PM

Originally Posted by Jim Luttrall

I could be wrong but that sure looks like a flexible gas connector, not armored cable.

AC would be preferred over NM if properly installed.

I think you are right about that , I was not on site for a "walk along" on this one , was reviewing these photos from an inspection and assumed that was an AC . I think this other pic (considering the position of the switch, which is on the opposite side) pretty much confirms that it actually a flexible gas connector and not AC. Thanks for the heads up.

The reason I posted this question is because I was told that NM wiring is "supposed" to be used for any furnace wiring , but have not found any info that backs this up. Considering also, that you are saying the opposite , I am going to have to find out what that person was getting at.

**Bob Elliott** · 10-27-2011, 11:27 PM

In the Chicago area conduit is used and BX is only allowed for 6 feet however what I see in the picture is a gas flex line.

The flex line should end outside the appliance and black pipe should have been run to protect the flex line from wear.
That knockout is sharp and the furnace vibrates.

UPC 1212.0 Appliance Connectors

(2) No part of such connector shall be concealed within or extended through any wall, floor, partition, or appliance housing.

Raghav Singh · 10-27-2011, 11:34 PM

Originally Posted by Bob Elliott

In the Chicago area conduit is used and BX is only allowed for 6 feet however what I see in the picture is a gas flex line.

The flex line should end outside the appliance and black pipe should have been run to protect the flex line from wear.
That knockout is sharp and the furnace vibrates.

UPC 1212.0 Appliance Connectors

(2) No part of such connector shall be concealed within or extended through any wall, floor, partition, or appliance housing.

Yes definitely a gas flex line. But thanks for posting code on proper wiring, that is probably why the inspector took this pic , I'll have to find out.

**Michael Bronner** · 10-28-2011, 10:24 AM

Confirmation on the flex gas line..that should not run into the interior of the furnace cabinet anyway..the flex connector manuf disallows it along with the Standard Gas Code. As far as having NM wiring to the furance, you really want to make sure the furance has a equipment ground connection that you would get with a Type NM 3 wire that is protected along its run to the furance and where it enters the furnace cabinet. Also, this is one way to make sure the gas line is bonded as well.

**Don Hester** · 10-28-2011, 02:03 PM

In response to the question on NM wire. I do not think that matters as long as the wire is rated for the application an in accordance of manufacturer's installation requirements.

But what does matter is that the cable be protected from mechanical damage. Many times the feeders are exposed in the furnace room.

I have seen where AHJ call this and other times not.

Raghav Singh · 10-28-2011, 04:10 PM

Originally Posted by Michael Bronner

Confirmation on the flex gas line..that should not run into the interior of the furnace cabinet anyway..the flex connector manuf disallows it along with the Standard Gas Code. As far as having NM wiring to the furance, you really want to make sure the furance has a equipment ground connection that you would get with a Type NM 3 wire that is protected along its run to the furance and where it enters the furnace cabinet. Also, this is one way to make sure the gas line is bonded as well.

Makes sense, so as Mr. Elliot had also mentioned..

Originally Posted by Bob Elliott

In the Chicago area conduit is used and BX is only allowed for 6 feet however what I see in the picture is a gas flex line.

The flex line should end outside the appliance and black pipe should have been run to protect the flex line from wear.
That knockout is sharp and the furnace vibrates.

UPC 1212.0 Appliance Connectors

(2) No part of such connector shall be concealed within or extended through any wall, floor, partition, or appliance housing.

This should atleast be reported for the fact that the flex line connector is "concealed within .... appliance housing."

So to sum up what has been said (If I understand this correctly--pls correct me if I got it wrong) one way this could have been done right, is to have the flex pipe hooked up to a black steel pipe connector outside of the housing. This would keep it from being affected by the sharp knock out which vibrates and may damage it.

The pic seems to be a good example of this done correctly.

That helps clear up alot , even though I confused the issue and derailed my own thread from the start , at least there is one more thing to look out for. Thanks

Raghav Singh · 10-28-2011, 04:32 PM

Originally Posted by Don Hester

In response to the question on NM wire. I do not think that matters as long as the wire is rated for the application an in accordance of manufacturer's installation requirements.

But what does matter is that the cable be protected from mechanical damage. Many times the feeders are exposed in the furnace room.

I have seen where AHJ call this and other times not.

Thanks for that ( sorry all ,for breaking this into 2 different questions, I know it makes it confusing/disorganized)

So if I understood this (again please correct me if I got it wrong) they should be installed in a way that would make it hard for people (or lawn mower, cars etc) from tripping/stepping/bumping/driving into or onto it?. Any additonal cautions?

Thanks, your response was much appreciated

**Jerry Peck** · 10-28-2011, 04:37 PM

The sediment trap in that last photo is wrong ... actually it is so wrong that I should not even call it a sediment trap, because it is not going to trap any sediment - that is, unless that gas connector goes from the valve to up, then turns down and connects to the top of the sediment trap (the photo is not from an angle which answers that question).

Raghav Singh · 10-28-2011, 04:49 PM

Originally Posted by Jerry Peck

The sediment trap in that last photo is wrong ... actually it is so wrong that I should not even call it a sediment trap, because it is not going to trap any sediment - that is, unless that gas connector goes from the valve to up, then turns down and connects to the top of the sediment trap (the photo is not from an angle which answers that question).

I'll try to get some more pics sent to me , apparently the inspector wrote this furnace up with a couple issues , probably has some more pics. If he has different angles , I'll certainly upload them.

Now, off to study proper installation sediment traps

Adrian Wilson · 11-01-2011, 06:31 PM

From what is visible from the last pic. my guess is that the connection is ok as long as that is the top of the heater with the gas inlet. Thought the bend in the connector is sharp the line did not seem distorted, flex lines should not be forced into 90 degree bends. On your first question, while the point of protecting the flexline from damage from rubbing sounds like a good idea, i question just how much vibration the heater has and if it's really in danger of touching the case. As to the assertion that it is hidden, if the access panel to the heater gives clear view to the connector, which would be normal since you need access to the gas valve I'm sure its connected to, is it hidden?. A flexline behind a heavy range you must use a floor jack to move is not 'hidden', nor a flex to a cooktop you have to remove drawers to see the line 'hidden line'. Running a flexline in a closed chase in an appliance or through a hole in the side that gives you full view of the flexline are not the same thing in my opinion.

**Bruce Ramsey** · 11-02-2011, 06:22 AM

Originally Posted by Adrian Wilson

On your first question, while the point of protecting the flex line from damage from rubbing sounds like a good idea, i question just how much vibration the heater has and if it's really in danger of touching the case...

When the fan starts up, the entire unit shakes and shimmies. How many times does the fan cycle on and off during a day. Lots of opportunity for the flex pipe to rub against the sharp housing.