Electrical installation – tedious tasks

May 11th, 2012
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There are a lot of decisions to make during a deep energy retrofit. It seems that all of them affect the energy performance one way or another and it is not always easy to strike the right balance.

In the last post I described the option of a service cavity or core, which would result in a better insulation integrity. Yet, we decided against it, trying to strike the right balance among competing interests.

With no service cavity, the electrical conduit installation in the perimeter walls becomes more elaborate. We have to drill through the studs for the conduit runs and fit them into the rockwool insulation. It gets really tedious where we have to get the conduits around wall corners.

As my conduit bending and installation skills grew thanks to Percy’s instructions, I became more confident and really wanted to take on this challenge. Plus, I thought my time is better spent on this then Percy’s, who already has taken quite some time teaching me.

 

Some readers may argue that Chicago’s code requirement to use electrical metal tubing (EMT) conduit is tedious in itself – forget about the wall corners!

So what would be the simpler version? Some building codes allow for the installation of a Romex type wire without the need for conduits.

See also: Fine Homebuilding – 9 Common Wiring Mistakes and Code Violations

Initially, I shared the opinion that Chicago’s EMT requirement was tedious. But I had plenty of time to think about it, while weaving conduit through wall corners.

The use of EMT conduit gives us flexibility. We can change, repair, upgrade or downgrade a wire without opening up a walls. All we need to do is to pull the old wire from the conduit and with ease add the new wire. That alone sold me on the conduit.

The EMT also acts as the grounding mechanism. I learned from Percy that it is called mechanical grounding. Because everything in the system is metallic, the conduit, the gang boxes, the couplings, the connectors, etc., it can carry a grounding load. That eliminates the need for a grounding wire.

Well, there is one exception. One panel in the basement has a dedicated grounding wire that is connected to the copper water main. This one short grounding wire closes the circle.

So, tedious? The conduits, not so much. Weaving them around the corners? Maybe. But I still had fun.


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Electrical installation – service cavity or core

May 5th, 2012
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A deep energy retrofit like ours often conflicts with standard construction practices.

Put an electrician in a situation like the one pictured above, and it is very likely that you find the electrical conduits installed behind the wood framing – because that would be the easiest and productive way to install it.

That actually happened to me in the basement unit, while I was not looking. Before I knew it, all the data cable wires were placed in, what I call, the insulation zone.

The primary reason why we don’t want any utilities in the insulation zone is to prevent thermal breaches – or weak links in the insulated envelope. Think of it this way:

There is a temperature gradient in the insulation. In wintertime it would be from cold toward the outside to room temperature on the inside.

The farther I place the electrical conduits towards the outside of the insulation cross section, the cooler they will be. And because the conduits are tubing that connect to the inside of the rooms at outlets and switches, they also become a perfect conduit channeling that cold into the cozy room interior. This would create a perfect thermal breach.

The farther I place the electrical conduits toward the inside, the more I keep the insulation cross section intact and the less likely of channeling cold temperatures into the rooms.

There is a new line of thought emerging that takes the issue of avoiding thermal breaches to a new level. That is, keeping electrical and plumbing completely out of airtight walls with a service cavity or service core.

The principal idea is to add a small wall to the existing wall on the interior of the building. All it takes is to fasten two-by-two furring strips horizontally to the insulation wall. The one-and-a-half inch cavity or core would be deep enough to accommodate electrical and plumbing while disentangling it from the insulation.

 

I do like this idea, not only because it eliminates thermal breaches, but because we are about to face the tedious task of fitting the electrical into the insulation wall. And while doing so, we have to keep it as close to the room interior as possible.

So why don’t I just install a service cavity or core? Because we have already reduced the room size by six and a half inches to get an R-value of 27. We don’t want to reduce the room size any more. And even if we did, I still would opt to add insulation into the service cavity to drive up the R-value.

Where and when could a service cavity become handy? In retrofit situations where the building is insulated from the outside, or, where the R-value of the outside wall is already at or near R-40.

You can read more about service cavities or cores and their applications at the GreenBuildingAdvisor.com blog “Musing of an Energy Nerd.”

Matthew Johnson liked this post

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Electrical installation – curving conduit

April 30th, 2012
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While my electrician Percy was bending his brain, developing a mental image of the wire routing and keeping track of the number of wires, I tried to be useful – and went shopping:

  • 500 feet of 1/2 inch EMT
  • 50 feet of 3/4 inch EMT
  • Four boxes of connectors
  • Four boxes of couplings
  • Four boxes of straps

I had the materials in hand but no clue where one should start with the installation. Percy did, and I simply began to follow his every move. Think of a five-year-old who can generate a seemingly endless stream of questions. That was me, although I tried to keep it under control.

The first thing that began to make sense to me was that a hot and a neutral wire have to feed into each room, usually into the ceiling box. From here wires will spider out across the room and down the walls to feed all outlets and switches.

We set the ceiling box, went around the room and installed a gang box at each outlet and switch location. With all the boxes in place, Percy began to connect them with the EMT conduit. That involves bending the conduit to fit around obstacles and corners or to point it into the right direction. To do so, there is an especially useful tool, the EMT bender.

Percy taught me how to bend stubs, offsets, kicks, back to back bends, and saddles. I just could have sat there and wasted the EMT on artwork!

Then there’s the issue of routing, which is a constant battle between the easiest route and the most material efficient route. I found out that they rarely coincide.

Learning how to bend the EMT was easy, but getting into the right mindset to figure out the best route took a little longer and more guidance. It is like three-dimensional problem solving, and I was completely hooked.


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Electrical installation – building a mental image

April 25th, 2012
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Lesson #1: Chicago is special …

… in so many ways. And so is the Chicago Electrical Code (Municipal Code of Chicago – Title 18 Building Infrastructure – Chapter 18-27 Chicago Electrical Code).

The code prescribes the use of electrical metallic tubing (EMT), commonly known as conduits, through which the conductors (wires) get routed. EMT are thin-walled metal pipes that come in 10 foot sticks. Typical diameter sizes used in residential construction are 1/2 and 3/4 inch.

Lesson #2: Count your conductors – or wires …

I don’t mean physically counting wires, but counting them in your mind. Because of my electrical illiteracy, I left this mindful exercise in the capable hands of my electrician, Percy.

Why do we need to count the wires? The Electrical Code sets a limit to the amount of conductors (or wires) allowed in an EMT. This is for two reasons:

  1. “… [to] permit dissipation of the heat [from the conductors] …” – In other words, prevent overheating of the wires.
  2. “…[to ensure] ready installation or withdrawal of the conductors without damage to the conductors or to their insulation.”

The rule is that for a 1/2 inch diameter EMT we cannot have more than:

  • 9 conductors (12 or 14 AWG)

For a 3/4 inch diameter EMT we must limit the number to:

  • 13 conductors (12 or 14 AWG)

Lesson #3: Wire terminology

Or should I say conductor terminology. Either way, what is AWG?

AWG stands for American Wire Gauge [LINK]. Number 12 is the a heavier gauge and is used for 20 ampere circuits, while number 14 is a lighter gauge and is used for 15 ampere circuits.

Another acronym you may run into while digging through the Electrical Code is conductor type THHN or THWN [LINK].

THHN stands for Thermoplastic High Heat-resistant Nylon-coated. This conductor type is suitable for dry and damp locations.

THWN stands for Thermoplastic Heat and Water-resistant Nylon-coated. This conductor type is suitable for wet locations.

I noticed that the wire we eventually used is rated both, type THHN and THWN.

Why do I need to know all this?

The electrical plans for the building are a schematic representation at best of what electrical fixtures and loads will be where. But all the details, like what goes onto which circuit and how to route the circuits, conduits and wires, are left to the electrical contractor.

Percy had to develop a mental image of how he could route the conductors from the breaker panel to each circuit and subsequently to each fixture. He needed to get a mental count of the number and type of wires. Where do we have a 20 ampere circuit that requires a 12 AWG conductor, and where will 15 ampere with a 14 AWG conductor suffice?

I was pretty much overwhelmed by that task and had no idea how Percy was able to form and hold on to that mental image and how he kept track of the number of wires needed. I guess it all comes down to aptitude … and experience.

All of this information was needed to determine where we should use 1/2 inch or 3/4 inch EMT, so that we can get started with the installation.

Anne Alt liked this post

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Electrical contractor

April 19th, 2012
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I have a major accomplishment to report: I found my first local contractor – an electrician. By local I mean from the community that we live in, North Lawndale.

Relying as much as we can on local resources (that includes contractors) has been one of our project objectives. The more local we go, the more resource efficient we can become. Plus, we would begin to circle money back into the local economy and community.

Project objectives and daily realities are often hard to reconcile. Forget about the local contractor. We had a terrible time finding any competent green industry contractors, point blank. I wrote about our struggles in a post called Service desert.

Imagine our delight when Harrison Electrical Contractors entered the picture. Here I not only had a local contractor, but someone who was interested in working on the project because of the green building components.

It became clear during the first meeting with the owner (Percy Harrison) that our project will be different from how things are usually done. Instead of being told that this or that won’t work, Percy didn’t say much at all. He listened and asked questions. I could tell how the wheels in his head were spinning.

Here I found somebody with the right mindset: “I will work with you to make it work for you.”

This may also help with my other problem or predicament: How can I properly plan the details for the electrical layout without a good understanding about the overall system?

I still have to keep learning while I am walking, but at least I found myself a tutor who will facilitate the process.

Kristin Faasse, Seth Barnhart, Chingwen Cheng, Anne Alt liked this post

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Electrical predicament

April 17th, 2012
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Oh boy! I am not quite sure where to begin.

I am pretty much illiterate when it comes to electrical issues. I know where my breaker panels are, how to check if one of the fuses is blown, and how to change a light bulb. But that is pretty much it. I don’t have an understanding of the big picture – or how the system works.

Although we had the new electrical system installed in the garden unit, I had very little involvement in that. I answered the occasional questions by the contractor on the location of fixtures, outlets and switches. That was it. There was no learning potential for me, which is also why there is no blog post on the electrical installation in the basement.

It is now time for the 1st floor electrical installation, and I would like to take a different approach. I have two main goals:

  1. To be more involved in the installation and in that process learn about the system and understand how it works.
  2. Rather than making decisions on the spot during the installation process, I would like to think through the details for the electrical layout ahead of time.

This sounds very simple and clear cut. But how can I properly think through the details for the electrical layout without a good understanding of the overall system?

Well, it looks like I am back in the business of learning while I keep walking.

Anne Alt liked this post

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Spatially challenged

April 8th, 2012
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Back in January, I described two useful plumbing gadgets. One of them was the the on-demand hot water circulation pump. I had to install it in a pretty tight space, in the plumbing wall.

Well, it turns out that I have to re-install it, because that day, I was somewhat spatially challenged.

Typically, the pump is installed under a sink, laying on the bottom in the vanity or base cabinet.

That orientation does not work in the plumbing wall, because I only have 5 1/2 inches to work with. The dimension of the pump, however, is 7 1/2 inches from front to back.

It got much more promising once I turned the pump up by 90 degrees. The pump depth is only 5 1/4 inches. Just about slim enough to fit into the plumbing wall.

I was happy with that solution — happy that I found a way around the spatial constraints — and I installed the pump accordingly.

It turns out that there is a good reason why the pump is typically laying on its side, with the cylinder cartridge in a horizontal position.

The cylinder cartridge contains the pump motor. The pump motor must be in a horizontal position for smooth operation and longevity’s sake. If the cylinder cartridge with the motor is in a vertical position, the motor has difficulties to maintain the same rotation. It may get out of whack and become unbalanced and noisy, and it eventually may break down.

How could I have known? To begin with, I could have followed the installation instructions more closely. Not only that, but we have a number of other water pumps in the utility room. And they are all installed with the cylinder cartridge in a horizontal position. Let’s call that a hint!

I was of the opinion that I did not have the room in the plumbing wall to position the cartridge horizontally. But all it took was to turn the pump by 90 degrees counter clockwise.

I am telling you – spatially challenged!

Matthew Johnson liked this post

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Furring channels

March 31st, 2012
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Our careful planning of the ventilation system begins to pay off. We sacrificed nine to 12 inches of the ten-foot room height in the less-public rooms. That gave us the space for drop ceilings, which accommodate the ERV ductwork.

Although we would like to preserve the full ten-foot ceiling height in the more public rooms, we have to accommodate the low profile utilities such as the insulated PEX runs and forthcoming electrical conduits.

Because the depth of the insulated PEX is only one and three quarter inches, we can provide enough space with a simple furring channel application.

This also gives us the opportunity for additional sound management or impact transmission control.

To prevent the transmission of impact borne noises, such as footsteps, I have to decouple the furring channels from the floor joists. We accomplish that with a device called the IsoMax Sound Clip. It is basically a rubber block with a profile cut-out for the furring channel and a metal bracket on either end through which the piece is fastened to the floor joist.

 

We added a half inch plywood piece between the floor joist and IsoMax to give us the required one and three quarter inch clearance space. As you can see, the furring channel is decoupled from the floor joist and fastening system through the rubber block.

We hope that this little trick will provide additional peace and quiet. Actually, we really, really hope so, because those IsoMax Sound Clips cost an arm and a leg – between $5.00 and $6.00 apiece. Do the math and you know we have an expensive ceiling.

Based on my research, there is only one company that offers this kind of sound control solution – Kinetics Noise Control. It looks like they pretty much can charge what they want with only one player in the market. I tell you, that is an expensive piece of rubber!

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Drop ceiling

March 24th, 2012
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While we are on the subject of framing, there are a few more carpentry tasks competing for my attention. One of them is the installation of drop ceilings.

The drop ceiling is needed to accommodate all the new utilities we installed on the first floor. These include the ductwork for the Energy Recovery Ventilator (ERV) and the PEX tubing for the radiators. We still have to add the electrical conduits.

The insulated PEX runs and forthcoming electrical conduits have a low profile and only require a clearance up to one and three-quarter inches. The ductwork for the ERV, six and eight inches in diameter, are a different story.

The framing

Only the master bedroom has an eight-inch diameter duct and thus requires a drop ceiling with a clearance of 12 inches. On each short end of the bedroom we mounted a 2 by 4 with joist hangers 16 inch on center, into which we placed the drop ceiling studs.

The other rooms with ERV ductwork have the six inch diameter kind, which requires a clearance of 9 inches. I had it easy and could attach the 2 by 4’s for the drop ceiling directly to the wall studs because they lined up with each other across the room.

Span support

The span of the 2 by 4’s for the drop ceiling is anywhere between eight to 12 feet. That is too much considering that I will hang heavy 5/8 inch drywall onto the ceiling. To prevent sagging, I need to support the 2 by 4’s every four to five feet, by attaching them to the floor joists of the second floor.

That gets me back into the issue of noise, or to be more precise, impact transmission – dampening down the noise of footsteps. We tackled the same issue while finishing the basement.

To decouple the support for the drop ceiling from the floor joists, and thus reduce the impact transmission, I used a neoprene bushing with a neoprene washer followed by regular steel washers.

 

As you can see, the long screw, which is the transmission rod for any vibration from the floor joists, is not in direct contact with the drop ceiling framing. The neoprene bushing and washer keep it from direct contact with the 2 by 4, and so does the over-sized hole above the washers (3/8 inch hole for a 1/4 inch screw).

The soffit

I have one short section of six inch duct that is running along a short wall in the living room. Rather than building another drop ceiling for the entire living room, we opted for a short and small soffit instead.


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Framing pocket doors

March 22nd, 2012
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The framing for the original pocket doors on the 1st floor is still in place, but not of much use to us. It is a little wobbly and doesn’t fit the replacement pocket doors we bought.

After a lot of inspecting, re-inspecting, measuring and some hurting brain cells, I decided that it made sense to remove the existing framing structure and start fresh.

The pocket doors with their oak construction are pretty heavy and it made sense to replace the existing 2 by 4 headers with something more substantial. I found two 2 by 10’s for a fair price at the ReBuilding Exchange that were long enough for the span. I am pretty sure that these are over-sized, but it is still better than the other way ‘round.

Then there is the issue of how to get the pocket doors to slide open and shut.  We have the intact roller mechanism that came with the doors. But I need to figure out a rail structure for the rolls.

 

The solution evolved from looking at the construction of other pocket doors and materials available to me on-site.

I mounted a half by three quarter inch oak rail onto a section of 2 by 4. The oak rail was ripped from scrap pieces that were left over from our window trim extensions.

 

The plan is to screw the 2 by 4 with the oak rail to the bottom of the header. Before doing so, the assembly is ripped to the correct depth and an angle cut away under the oak rail. This should prevent the mechanism from jamming or getting stuck.

I also plan on lubricating the oak rail with paste wax before employing the doors. I hope that will facilitate an easy opening and closing, although I have to fry other fish first, such as adding three inches to the top and bottom of the doors.

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