EMT Conduit inside walls and throught the house

[tk3000]

Sometime ago I talked about deploy emt conduit throughout the house and inside walls as risers going up to the ceiling and attic. It is my understanding that the the romex is not going to be inside a conduit 100% of the time, one can fill it up to 100% (100% filling rate). Using romex gives the flexibility of transition from conduit to no-conduit situations(small segments, unpractical situations for conduit, etc). In some situations, specially whereas 3 wires are required in a 20 amps circuits and plus which will travel inside conduit all the time, I will likely use THHN wires (especially because I don't intend to use ¾ emt conduit).

Using the emt as a riser from an outlet box inside walls I plan to use the following configuration:

by which instead of bending the conduit in the attic (which would a nightmare), once the conduit enters the attic through the joist it will connected to a junction box right away.

The following the pic shows from behind a conduit connected to a future outlet box in the kitchen area with an emt rising to the ceiling. And since it is inside the emt conduit which is affixed to the box, I was wondering whether or not the requirement for straps/clamps are. I heard that in some situations the requirement would be: position straps within 3 ft. of each box and within 10 ft. thereafter. Also, since the knockout in the box and the hole above in the ceiling are well aligned, there were no need to offset the conduit; but the emt conduit are not making direct contact with the stud which then would make it difficult to use straps in this case.

In the basement, I am also using conduit 95% of the time, as shown below:

There is a situation whereby the nm-b exist the "wall" throught a hole directly to a box (which will have a switch and outlet) through its back (back knockout hole) but then there is not room for a fitting (which does not seem necessary due to the fact that the hole in the wall is much smaller than the knockout , but in any case I used an anti-short bushing to protect it. Would that be ok codewise? I was wondering whether or not these small plastic anti-short bushings are required or not (it seems prudent to use them, specially with bx/mc conduit)

thks!

 

[slownsteady]

The setup looks pretty impressive, but I have to ask "Why bother?" There are gazillions of miles of romex running through the walls of houses all over North America with a very low percentage of problems.

 

[Sparky617]

The setup looks pretty impressive, but I have to ask "Why bother?" There are gazillions of miles of romex running through the walls of houses all over North America with a very low percentage of problems.

Not in Chicago though. If not required to run conduit, I'd use Romex. A couple of runs from the basement to the attic for future needs isn't a bad idea. I have two runs in my house, still unused after 16 years but they're there if I need them. With WiFi becoming so widespread, and I have two WiFi routers in my house to give great coverage throughout I may never need these runs.

 

[slownsteady]

So, Chicago requires conduit in the walls?

 

[Snoonyb]

So, Chicago requires conduit in the walls?

Can anybody say, UNION!

 

[Snoonyb]

Sometime ago I talked about deploy emt conduit throughout the house and inside walls as risers going up to the ceiling and attic. It is my understanding that the the romex is not going to be inside a conduit 100% of the time, one can fill it up to 100% (100% filling rate). Using romex gives the flexibility of transition from conduit to no-conduit situations(small segments, unpractical situations for conduit, etc). In some situations, specially whereas 3 wires are required in a 20 amps circuits and plus which will travel inside conduit all the time, I will likely use THHN wires (especially because I don't intend to use ¾ emt conduit).

Using the emt as a riser from an outlet box inside walls I plan to use the following configuration:

by which instead of bending the conduit in the attic (which would a nightmare), once the conduit enters the attic through the joist it will connected to a junction box right away.

The following the pic shows from behind a conduit connected to a future outlet box in the kitchen area with an emt rising to the ceiling. And since it is inside the emt conduit which is affixed to the box, I was wondering whether or not the requirement for straps/clamps are. I heard that in some situations the requirement would be: position straps within 3 ft. of each box and within 10 ft. thereafter. Also, since the knockout in the box and the hole above in the ceiling are well aligned, there were no need to offset the conduit; but the emt conduit are not making direct contact with the stud which then would make it difficult to use straps in this case.

In the basement, I am also using conduit 95% of the time, as shown below:

There is a situation whereby the nm-b exist the "wall" throught a hole directly to a box (which will have a switch and outlet) through its back (back knockout hole) but then there is not room for a fitting (which does not seem necessary due to the fact that the hole in the wall is much smaller than the knockout , but in any case I used an anti-short bushing to protect it. Would that be ok codewise? I was wondering whether or not these small plastic anti-short bushings are required or not (it seems prudent to use them, specially with bx/mc conduit)

thks!

Whats the general motivation in selecting EMT?

 

[Sparky617]

Can anybody say, UNION!

I think the motivation was fire code after the great Chicago fire. But, millions of homes in the USA have had Romex since the post WW2 building boom. I don't live in the Chicago area but I believe even in single family construction the requirement is still for EMT.

But yes it is a great tool for keeping union electricians employed and skilled DIYers out of doing home improvements.

 

[Snoonyb]

I think the motivation was fire code after the great Chicago fire. But, millions of homes in the USA have had Romex since the post WW2 building boom. I don't live in the Chicago area but I believe even in single family construction the requirement is still for EMT.

An acquaintance, who works here on the truly left coast in the winter, from Chicago, confirms that.

There are a couple additional union based restrictions, which have been overcome, and they are the slot-head screw and the bond bushing for grnd.

But yes it is a great tool for keeping union electricians employed and skilled DIYers out of doing home improvements.

Occasionally in older homes we will find iron pipe for switch legs.

 

[slownsteady]

Ah yes, the Chicago fire. of course! We don't want any cows kicking over the romex.

 

[CallMeVilla]

Odd to see this .... conduit is such a pain for bending .... why not use MC which is flexible, fast, and meets commercial code too?

 

[tk3000]

Odd to see this .... conduit is such a pain for bending .... why not use MC which is flexible, fast, and meets commercial code too?

There is some MC conduit+wire that was installed in the house when they upgrade the water heater to an electric one at some (since it seems much newer than the majority of the electrical installation), I probably will keep it and expand on it a little. But then MC is more expensive and probably not a good choice for upgrading (or running additional) wires in the future. It is not only electrical wires, but the conduit could also be used to run low voltage wires for sensors, cameras, etc.

By the way, the MC wire likely installed in the last 5 years present at the house was hooked up to a junction box without any fitting and the MC wire seems to prone to have very rough ends. Below is a pic of the a mc wire end that goes to an j-box that found, and all the wires coming out of it are damaged due to its rough ends. I will cut off the bad part, and use anti-shorts:

Yeah, I know it is pain to bend, measure, etc; but no pain = no reward

 

[Snoonyb]

There is some MC conduit+wire that was installed in the house when they upgrade the water heater to an electric one at some (since it seems much newer than the majority of the electrical installation), I probably will keep it and expand on it a little. But then MC is more expensive and probably not a good choice for upgrading (or running additional) wires in the future. It is not only electrical wires, but the conduit could also be used to run low voltage wires for sensors, cameras, etc.

By the way, the MC wire likely installed in the last 5 years present at the house was hooked up to a junction box without any fitting and the MC wire seems to prone to have very rough ends. Below is a pic of the a mc wire end that goes to an j-box that found, and all the wires coming out of it are damaged due to its rough ends. I will cut off the bad part, and use anti-shorts:

Yeah, I know it is pain to bend, measure, etc; but no pain = no reward

So, you are not concerned about cross-talk between your HV and LV, in the same conduit?

The original metallic wrapped was called bx and it was common practice to wrap the conductors at the exit points with friction tape.

I always had the thought that the industry had gotten ahead of itself, with bx, and It's taken some time to catch up.

 

[tk3000]

So, you are not concerned about cross-talk between your HV and
LV, in the same conduit?

The original metallic wrapped was called bx and it was common practice to wrap the conductors at the exit points with friction tape.

I always had the thought that the industry had gotten ahead of itself, with bx, and It's taken some time to catch up.

There will be a separate conduit for high speed bandwidth in order to avoid cross talk. Now the bitstream of data going to/from the sensors would likely use OneWire protocol and would not suffer from any magnetic field due to be way too simple and with tiny small amount of data flow. In practice most basic video stream does not seem to suffer either (but that is another story), but it is mostly for sensors anyways (tons of them)

 

[CallMeVilla]

.By the way, the MC wire likely installed in the last 5 years present at the house was hooked up to a junction box without any fitting and the MC wire seems to prone to have very rough ends. Below is a pic of the a mc wire end that goes to an j-box that found, and all the wires coming out of it are damaged due to its rough ends. I will cut off the bad part, and use anti-shorts:

ALWAYS use anti-shorts .... required by code and just makes common sense.

:

 

[Snoonyb]

There will be a separate conduit for high speed bandwidth in order to avoid cross talk. Now the bitstream of data going to/from the sensors would likely use OneWire protocol and would not suffer from any magnetic field due to be way too simple and with tiny small amount of data flow. In practice most basic video stream does not seem to suffer either (but that is another story), but it is mostly for sensors anyways (tons of them)

OK. Back to the original question; Blocking, both vertical and horizontal will afford the attachment locations.

The original octagon box you replaced with a square box had a connector preventing the romex be pulled out of it. Just an isolation bushing corrupts that and the romex can be pulled out. Romex is required to be attached at all box entry points.

 

[slownsteady]

About that square box (now that we finished talking about why conduit): The bushing does nothing that a quick scrape with sandpaper wouldn't fix. BUT; if the whole purpose of a jbox is to contain any 'hot spots' that may occur, then that little bit of wood behind the box should be protected. No? Kind of defeats the purpose of all that nice metal conduit.....

 

[tk3000]

About that square box (now that we finished talking about why conduit): The bushing does nothing that a quick scrape with sandpaper wouldn't fix. BUT; if the whole purpose of a jbox is to contain any 'hot spots' that may occur, then that little bit of wood behind the box should be protected. No? Kind of defeats the purpose of all that nice metal conduit.....

I realize that the wood does not represent any roughs surface likely to mar the nm-b sheathing, I did not that just for consistency (everything has bushings/fittings).

Only because a small section of the romex is exposed (made clear since the beginning that 95% of the romex would be protected in the basement, there are 5% that may not be), does that defies the purpose of having the vast majority of the romex protected and upgrading/updating ready? Is this irony or something?

 

[tk3000]

OK. Back to the original question; Blocking, both vertical and horizontal will afford the attachment locations.

The original octagon box you replaced with a square box had a connector preventing the romex be pulled out of it. Just an isolation bushing corrupts that and the romex can be pulled out. Romex is required to be attached at all box entry points.

The original box did not have a retaining fitting at the back of the octagonal j-box (it had on both sides though). There is no big deal installing a retaining fitting in the back of the box, but I would have to bore a partial hole on the wall/joist; anyhow in this situation the romex comes from the back of a wall cavity and thus it would be very difficult for someone to pull it out (even at the other end of the wire: the other jbox is located on the other side of the wall, so this very small segment [maybe 2 feet] of romex is basically travelling between two sides of the same wall). But I can always bore a partial hole and add a retaining fitting if is required.

 

[Snoonyb]

The original box did not have a retaining fitting at the back of the octagonal j-box (it had on both sides though). There is no big deal installing a retaining fitting in the back of the box, but I would have to bore a partial hole on the wall/joist; anyhow in this situation the romex comes from the back of a wall cavity and thus it would be very difficult for someone to pull it out (even at the other end of the wire: the other jbox is located on the other side of the wall, so this very small segment [maybe 2 feet] of romex is basically travelling between two sides of the same wall). But I can always bore a partial hole and add a retaining fitting if is required.

Ok. But if someone were to remove that box on the other side, they could then pull the romex to the limits defined by the connection within, not the romex connector required.

Building codes are designed to protect you, from you.

 

[slownsteady]

Only because a small section of the romex is exposed (made clear since the beginning that 95% of the romex would be protected in the basement, there are 5% that may not be), does that defies the purpose of having the vast majority of the romex protected and upgrading/updating ready? Is this irony or something?

I was more interested in pointing out that the wood is exposed to the inside of the jbox.