Saving Money on the Electrical System

With this post, I’m taking a step back in time to the spring of 2014.  Hopefully my experience will be helpful to someone who is thinking about doing their own electrical work for their new home…

Call me naive, but at some point early in the planning stage I had a brainstorm and decided that I was going to install the electrical system.  It seemed like a great place to save some fairly serious money, as the original bids ranged from $12,000 to $18,000.  Although it didn’t quite work out that way, I did manage to cut the total cost down to about $10,000.  But even in a relatively modest house like this, these savings required a lot more thought, planning, and work than I had imagined.

The first thing I needed to do was get power to the house.  And before doing that, I had to decide where the meter would go.

I knew from the start that I didn’t want the electric meter hanging off the side of the house.  I figured that it would be one more complication when it came to the exterior foam and siding installation that we didn’t need.  Fortunately, the garage was to be located between the house and the electric transformer.  So I decided to put the meter on the garage, and then run power from there to the house.

[As a side note, my house sits over 500 feet off the road, and when I purchased the lot I didn’t even think about what it would take to run electricity to it.  Fortunately, many years ago, in order to service several houses on adjacent lots, the electric company had already installed a transformer near the corner of my lot that happened to be closest to my  building envelope (less than 100 feet away). So I got lucky in that regard.  I don’t know how much it would have cost to have the electrical supply run the 500 feet from the road to the house,, but I am told it would not have been insignificant.]

Putting the meter on the garage brought it’s own complications; it required that I get conduit in the ground between the house and garage as the garage foundation was being installed.  We’d also have to install a switch in the garage that would be able to completely shut down the power to the house sub-panel that would be installed in the basement.

I decided that this aspect of the job was beyond anything I wanted to try to tackle.  So I set out to find an electrician.  I called eight electricians and left messages explaining what I needed to do.  Only one called me back.  He was a one-man operation, and agreed to do the job with my help in laying the conduit.  The cost would be roughly $4,000.

After the footers were poured, and after consulting with my excavator and the electrician, I had my excavator dig a straight-line trench from the spot where the main panel would be placed to the house.  The specific location of the box on the garage was a critical decision.  My initial thought was to put the box on the back of the garage.  But that would have required a longer run and at least one additional turn in the conduit.  And the more turns in the conduit, the more difficult it would be to pull the wire through (or to pull it out).

In this photo, you’ll see the main three-inch conduit, and the two one-inch conduits for the generator and garage light switches.  The third one-inch conduit is for Comcast.  We ended up using Verizon Fios, and the installers decided not to use it.

Once we settled on the placement of the main box (early fall 2013), I assisted the electrician with setting the conduit; the main feed to the house (3″), a secondary feed that traversed the yard in front of the house for the future second garage (2″), a smaller conduit so we could control the exterior garage lights from a switch in the house (1″), another smaller conduit so I could power the house sub-panel with a generator that would be plugged in in the garage (1″), and a conduit to run Comcast cable from the garage (which was also closer to the Comcast box) to the house (1″).

IMG_0228 1IMG_0226 1

At the house, I initially intended to run the conduit through the foundation wall below grade.  But in the end, that seemed like more work than it was worth, and should have been planned before the house foundation was poured.  So we brought the conduit up just outside the foundation, and ran the electrical through the rim joist.  The following photo shows the conduits entering through the rim joist:

IMG_1014

After the conduit was put in place, the electrician disappeared, for months.  That, by the way, was not unusual for the contractors that I encountered.  I’m guessing that some of them are horrible businessmen, and others simply place independent guys like me at the bottom of the priority list.  What I don’t get is why they can’t manage a five minute phone call or a 30 second email just to let me know they’re still alive.  Seems like common courtesy.  But I digress…

Just as I was giving up hope, he reappeared, claiming that he had been ill and hospitalized.  By that time, it was late December.  He showed up and fed the cable from the garage to the house, coordinated with the electric company and finished the job.  However, before the electric company would tie us in to the system, the work had to be inspected.  So he called an inspector, who came out and signed off on the job.  Once that was done, the power company completed the connection and powered up the system.  By then it was late January.

A couple of months later, I needed to install the recessed lighting in the porch and pent roofs because the siding subs were ready to install the beadboard ceilings.  So I purchased the fixtures, installed them, and wired them in.  When I finished, I called the electrical inspector that I was instructed to call by the building inspector.  This guy was not the same guy that the electrician used for the inspection needed to get power to the house.

I didn’t know it at the time, but in our township, the electrical inspectors work for private companies.  Apparently, many electricians develop relationships with a particular inspector, and call that person out to inspect their work.  And of course, the inspector that this electrician used was not the electrical inspector that my building inspector had assigned to my house.

When the “official” electrical inspector showed up, he quickly gave my work the OK. Then he noticed the panel in the garage and asked why it hadn’t been inspected.  I explained what had happened, and he walked over to take a look.  He quickly found two problems.  First, the electrician had only installed a single grounding rod, whereas two were required.  And second, the electrician had used the wrong wire in the conduit from the main (garage) panel to the sub panel in the house.  I’m not sure exactly what was wrong with it.  But I think the problem was that the wires were encased in a sheathing, much like typical Romex.  Evidently, the code had changed in our area, and the wires had to be of a type that is unsheathed, when run through underground conduit.

I have no idea why the prior inspector didn’t catch these problems.  But it didn’t matter.  It had to be re-done.  Fortunately, the electrician took it in stride and showed up.  I helped him pull the cable out, put the new cable in, and install the second grounding rod.  Fortunately, because the run from the garage to the house was straight, pulling the 60 feet of cable out of the conduit only took five minutes.

That was pretty much it until I finished the interior framing.  Once that was done, my next task was to install all of the electrical fixtures in preparation for wiring.  This turned out to be close to 200 items.  Boxes for outlets. Boxes for switches.  Boxes for sconces.  Boxes for ceiling lights.  Boxes for ceiling fans.  Boxes for fire alarms.  Boxes for the water heater, the ERV, and the minisplits.  Outdoor outlet boxes.  Boxes in the garage.  Recessed light fixtures, closet light fixtures.  Porch “carriage house” light fixtures.  Light fixtures on the outside of the garage. The number amazed me, particularly given the size of the house.  I had never imagined that there could be so many.

But it wasn’t just the number of fixtures that took so much time.  It was also the placement of the fixtures.  In the bathroom we used sconces on each side of the mirrors; that’s four sconces in the master bath and two in the guest bath.  This required me to decide exactly how big the cabinets would be, how large the mirrors would be, and the size and style of the fixtures.  Since I hadn’t yet built the cabinets, and we hadn’t yet picked out light fixtures, this was challenging.

For every area of the house, when it came to lighting the questions were how many, what type (e.g. ceiling, wall, or recessed) placed where (e.g. how far apart, how many rows, how high on the wall, how far from the door/window), and controlled how (e.g. a single switch, three-way, four-way)?

I ended up making significant use of sconses.  Two in they foyer, two in the family room, one in the back hall, four in the second floor hall, eight in the bathrooms, and two in the master bedroom.

To keep penetrations through the second floor ceiling at a minimum, I used half-inch deep pancake boxes for the bedroom ceiling fans, closet lights and bathroom ceiling lights.  I attached these boxes directly to the Zip ceiling (reinforced from above as necessary for the fans).  In doing this I only needed to drill a half-inch hole through the Zip ceiling for the wire, instead of cutting a four-inch hole for the entire box as is typical.  Once the drywall was completed, these boxes were flush with the finished surface.  I also placed the second floor smoke detectors and the bathtub and shower lights high on the wall instead of in the ceiling.

At the same time, I had to be mindful of the code requirements, which dictate, among other things, how far apart outlet boxes can be and how high the fire alarms must be placed.  I also tried to be mindful of the drywallers by keeping outlet box heights consistent and switch box heights set at the drywall seams.

I had to ensure that I had the necessary exterior light and outlet mounting plates/boxes in place before the guys installed the siding on the house and the stone on the garage.

And I had to ensure that the wall boxes were set at the proper depth; basically 1/2″ for interior walls and 5/8″ for the perimeter walls.  In most cases, on the perimeter walls, I used adjustable boxes; where the surface of the box could be moved in or out after the drywall was installed.  They were more expensive, but well worth it.

All in all, it wasn’t particularly difficult.  It just took a lot of thought, planning, and time. It took me weeks, off and on, to get everything in place, exactly where I wanted it.

I finished all of the above work in May 2014, and started to run the wire.  I finished wiring the recessed ceiling lights in the kitchen, family room, and office, and realized that it was just going to take too much time for me to finish the job on my own.  Again, it wasn’t so much that it was difficult, it was just too time consuming.  So I contacted another electrician that had done some work for me in our prior house, and it proved to be a good move.  He, his son, and one employe spent three days on the house.  They worked like a well-oiled machine and finished the rough-in, running all of the wires hooking everything up to the breaker box in the basement.  That cost me another $4,000.  But it was well worth it.

That was it until the insulation, plumbing, and drywall were finished.  Then it was back to work on the electrical.  Fortunately, the electricians had done a great job of organizing the wires neatly in the boxes.  I was able to install all of the 200 or so outlets and fixtures without a single problem, although, again, it took a lot of time.

I was subsequently warned by someone in the business that some less ethical electricians sometimes screw with a customer who wants to install the fixtures himself.  As I was told, they do this by first telling the person something like, “I’ll do the entire job for $8,000, or I’ll do the rough-in only for $4,000.  But if I have to come back and install the fixtures, it will be an additional $5,000.” Then, if the customer chooses the rough-in only option, the electrician wires the house in such a way that it becomes very confusing when it’s time to install the outlets and fixtures; almost assuring that the customer will have to call him back to complete the job.

Fortunately that wasn’t the case with my electrician.

 

 

 

ERV Balancing – The Trim Setting

A couple of posts ago, I talked about how the ERV was out-of-balance, which placed the house in a state of negative pressurization and increased the radon levels.  When I rebalanced the system, I became a bit concerned because I had to completely open all of the supply vents and slightly close a couple of the exhaust vents to get the house into a state of positive pressurization.  That just didn’t seem right.  I installed the system, and I knew that all of the supply and exhaust lines were hooked up properly.  So I couldn’t understand how the supply flow could be that much lower than the exhaust flow.

Several days later, with that issue still on my mind, I pulled out the report that was prepared when the system was commissioned, and read through it again.  It was then that I noticed a box in the lower corner called “Trim,” which seemed to indicate that the supply and exhaust fans could be, and were, adjusted independently, so the supply fan ran at a lower speed than the exhaust fan at each of the three speed settings (low/medium/high).  This was particularly interesting because up until that moment I assumed there was only one fan in the unit.

That prompted me to read the ERV manual, and several things fell into place.  The ERV does, in fact, have two independent fans, and yes, these fans can be adjusted independently of each other.

I then checked the actual settings and found that, as the Trim box on the report indicated, the fans were adjusted to the stated levels during the commissioning process.  For each speed setting (low/medium/high), the tech set the fans to operate at a certain percentage of full power.

One (i.e. me) might think that the fans would be set to operate at the same level at each of the three speed settings.  But that wasn’t the case.  For instance, at the “low” speed setting, the supply fan was set at 39% of full power and the exhaust fan was set at 45% of full power.  At the “medium” speed setting the fans were set to 56% (supply)  and 62% (exhaust), and at the “high” speed setting, they were set to 78% (supply) and 95% (exhaust).  So basically, the intake fan was operating at a level that was 10% to 15% lower than the exhaust fan.

I’m sure there was a reason for setting the supply fan to run at a lower speed than the exhaust fan at each power level, and ultimately I’m sure that reason was to ensure that the system was in balance.  I suspect that one may need to adjust the fans independently because the supply lines and exhaust lines are rarely, if ever, going to be the same lengths, and the difference in lengths play a role in the amount of resistance.  The same goes for the ducts that go from the ERV to the outside.  In my house, the exhaust duct is at least twice the length as the supply duct.

But regardless of the reason, the goal clearly wasn’t achieved.  Not only was the goal not achieved, but the difference between the settings left the system far enough out of balance to make it impossible to bring it in balance without completely opening all of the supply vents and slightly closing some of the exhaust vents.  In fact, even when the system was initially balanced, the tech didn’t install baffles in several of the supply vents, which should have been a clue that something was amiss.

Fortunately, changing the trim settings is a simple process that is explained in the manual. Once I adjusted the fans so they were operating at the same level at each speed setting, balancing the system (and creating a slightly positive pressure in the house) became a lot easier.  And since there is no longer any need to fully open all of the supply vents to achieve that goal, I can now set the flow at each supply and exhaust vent to the proper setting.

 

Radon – Part 2 – The ERV

Several months ago, I posted about the radon problem that I discovered, and how I solved it.  Shortly after writing that post, I was contacted by Marc Rosenbaum, Director of Engineering at South Mountain Company,  a design/build firm in West Tisbury, MA.  Marc was interested in the radon issue, and offered a thought that had not been raised by anyone else I had spoken to. In short, he suggested that an imbalance in my ERV could possibly have been the cause of, or at least a contributing factor to, the relatively high levels of radon in my house.

His theory went something like this…The ERV is supposed to be balanced; it is supposed to draw in the same amount of air as it expels.  When that is the case, the interior of the house is neither positively nor negatively pressurized (with respect to the outside air).  It is neutral.

If the ERV is drawing in more air that it is expelling, the interior of the house will be in a state of positive pressurization.  In this state, the excess inflow of air will try to find a way out through any gaps that are present in the building envelope because it cannot all get out via the ERV exhaust duct.

But if the ERV is expelling more air than it is drawing in, the interior of the house will be in a state of negative pressure.  In this instance, the ERV is going to pull air into the house through whatever cracks/gaps exist to make up the difference between the smaller volume of air coming through the ERV intake and the larger volume of air moving through the ERV exhaust.  Since some of these entry points are inevitably going to be in the foundation, if the soil contains radon the incoming air is going to bring that radon with it. And this is essentially what Marc thought might be happening.

I have to admit that it was difficult for me to believe this could happen.  My house tested out at .3 ACH @ 50 pascals.  I saw how the basement slab was constructed and sealed.  I just couldn’t imagine that an imbalance in the ERV could suck enough (i.e. any) air through the foundation to make the radon level increase.  I assumed that radon particles are so small they can move through things that air cannot.

Marc then made the idea more mind boggling by saying that the radon fan might be contributing to the negative pressure situation even as it solved the radon problem.  This also made no sense to me.  How could that little fan – one with the lowest airflow I could find – possibly be powerful enough to suck so much air through minuscule gaps in the foundation that it would change the internal pressure in the house? It just didn’t seem possible.

Well, as I have come to learn, Marc appears to have been correct on all counts.  The ERV was out of balance and causing the house to be negatively pressurized.  That negative pressurization was causing the radon problem.  And the radon fan was increasing the negative pressure even as it solved the radon issue.  It was doing that by sucking air out through the gaps in the foundation floor, which in turn pulled air into the house through whatever gaps are present above the foundation floor.  This of course isn’t good, because none of that air is filtered. But on the upside, at the same time, the radon fan was pulling the radon from the soil under the house and expelling that radon to the outdoors, thereby reducing the radon level in the house.

To determine whether Marc’s theory was correct, Marc suggested that I check to see if the house and the ERV were balanced by using a manometer, like the one pictured below:

DM-2

The manometer measures the relative difference in pressure between the interior of the house and the outside air.  Basically, you do this by running a flexible tube from one valve on the manometer to the outside, and leaving a second valve on the manometer open to the inside of the house.  The manometer does the rest, with the results displayed in “Pascals.”  Ideally, if the ERV is balanced, the manometer should display a reading that will probably fluctuate, but stays close to zero (The calmer the wind outside, the more stable the reading will be), thereby indicating that the pressure in the house is the same as the pressure outside the house.

With (once again) the help of my Passive House Rater, I was able to take measurements with the radon fan off, the ERV off, both off, and both on.  This enabled me to see the effect that each was having on the interior house pressure.  The reading we got supported Marc’s supposition. The manometer showed that the house was negatively pressured by eight to ten Pascals with both the ERV and radon fan running.  Most of this (about five to six Pascals) was due to the ERV.  About three to four Pascals were due to the radon fan.  So, both the ERV and the radon fan were pulling air into the house through the cracks and gaps that were simply too small to find and close.

This led to the question of “why?”  Why wasn’t the ERV balanced?  The purchase price for a Zehnder ERV includes a $500 fee for commissioning (i.e. balancing).  Zehnder mandates that their own person commission the system because they want it done correctly.  Well, it appears that the problem with my house wasn’t the person who did the work, it was the equipment that he used.

The Zehnder ERV that I installed in my house has ten individual interior supply ducts (which bring fresh, filtered air into the house) and ten individual interior exhaust ducts (which expel stale air from the house).  Those two airflows need to be the same for the system to be in balance.  [Note: This is different than interior supply and exhaust vents.  In my house, there are eight supply vents and six exhaust vents.  Some vents have one duct attached (e.g. the powder room exhaust vent), some have two ducts attached (e.g. the main floor supply vent), and one has three ducts (i.e. the kitchen exhaust vent).]

To balance the system, the tech person went from room to room and opened or closed each vent until a pre-determined amount of air flowed through it.  This was done by checking the flow through each of the vents, one at a time.  Since adjusting the flow at one vent can change the flow at another, the complete process must be performed a number of times.  So once all eight supply vents were checked and adjusted, the tech started at the beginning and checked/adjusted them a second time, tweaking each to get it as close to perfect as possible.  And then he checked them a third time.  In fact, I think he ended up checking them five or six times before he was satisfied. The same went for the six exhaust vents.   The process was completed when the tech felt that he had each vent adjusted as close to perfect as possible.  And at that point, he concluded that the system was balanced, with (in my case) about 120 cfm being supplied and 120 cfm being exhausted when the ERV is set to medium speed.

The problem is that there is a margin of error in the equipment used to measure the flow at each vent, and some equipment has a greater margin of error than other equipment. More specifically, Zehnder used a rotating vane anemometer on my house.  It looks like this:

testo_417_vane_anemometer

One evaluation of that equipment indicates that it could result in an error of up to 25%:

Download (PDF, 2.05MB)

That margin of error is further complicated by the fact that the anemometer display never stays static.  Rather, it bounces around a bit.  For example, it may be that the best that can be done is get a reading that bounces from 11.1 cfm to 13.3 cfm for the single duct powder room exhaust vent, leaving the operator with the task of interpolating the results.  In that instance, it might be fair to say that the results look like 12 cfm, on average.  But who knows what the actual reading really is?  And at airflow levels as low as that, being off 1 or 2 cfm each time you check a vent can add up.

And therein lies the problem.  If the equipment is inherently inaccurate and the tech is off in his interpolation of the data, it is not difficult to see how the ERV could end up being unbalanced.  That is essentially what appears to have happened at my house.  But I digress…

After seeing that the house was negatively pressurized, my Passive House rater, who has been a big help to me throughout the entire building process, measured the flow at the exterior vents using a more accurate devise known as a “power hood.”  Although the wind was preventing us from getting a steady reading, we estimated that the intake was bringing in 10 to 20 cfm less than the exhaust was expelling.

Unfortunately, Zehnder doesn’t check the overall flow at the exterior vents, primarily (they say) because those vents often are not easily accessible (although on my house they couldn’t be more accessible) .

Fortunately my Passive House rater helped me use his equipment to rebalance the system.  Essentially, what I ended up doing was opening up all of the supply vents and slightly closing a couple of the exhaust vents.  By monitoring the effect these changes had on the house pressure with the manometer, I was able to bring the interior of the house in balance with the outside air.

While doing that, I found that the balance and pressure are also affected by the speed at which I run the ERV fan.  When the ERV is set on “low” speed (i.e. Level 1), the house is now pretty much neutrally pressurized, with a reading that fluctuates between -1 and +1 Pascals, and probably leans more toward the +1.  But when set on medium (i.e. Level 2), the house is clearly positively pressurized, with a reading between +1 and +2 Pascals.

Once I completed the rebalancing, I waited several days to see what effect it would have on the radon level.  Prior to rebalancing the ERV, the radon fan had brought the radon level from about 6 pCi down to about 1pCi, and within three days of unplugging the radon fan (which I did a couple of times just to check), the level consistently rose back to 6 pCi.  But this time was different.  With the radon fan off and the ERV on low speed, the radon never rose above 1.4 pCi, comfortably below the mitigation threshold of 4pCi.  When I set the ERV to medium speed, the radon level dropped further (although, so far, never to zero).

One final note…All of this occurred this spring, and we rarely use air conditioning.  So as it turned out, we started opening windows a couple of weeks after the rebalancing.  Some days we only opened the first floor windows.  Some days only the second floor windows.  And some days both the first and second floor windows.  Also, on some days, we opened a window (or windows) for only a short period of time.  At other times, we left windows open all day or for several days at a time.  But regardless of the number of open windows or the amount of time they were left open, it soon became clear that opening windows had an effect on the radon level (which we measure in the basement).  The longer a window or windows were open, the higher the radon level rose.  The up-tick in the radon level is very slow, but given enough time (i.e. days) the level eventually rises as high as 2.4 pCi (still not bad).  And if the windows are left closed, the radon level slowly comes back down to about 1 pCi.  Subsequent testing with the manometer showed that opening even one window threw the house into a slightly negative pressure situation.  Whether its the “stack” effect, the wind, a combination of both, or something else, I don’t know.  But the effect seems to be consistent.

With regard to the stack effect, even on a hot day the temperature on the second floor is no more than one degree higher than the first floor.  But the temperature difference between the first floor and the basement is more substantial.

Septic Tank Leak

Earlier this summer, as I was working on the interior framing of the house, I noticed the sound of dripping water.  The weather was clear, but it had rained the prior day.  At first, I ignored it.  But after a couple of hours of listening to it, I decided that I needed to track it down.  In a few minutes, I was able to zero in on the source; the first floor toilet drain.  The plumber had finished installing his system a few days earlier, and, in doing that, connected the drains to the septic line in the basement.  Since the noise was coming from the drain, I went outside and lifted the two concrete access covers on the septic tank.

Although no toilets or faucets were installed, the tank had at least a couple feet of dirty water in it.  The problem was the two risers that connected the tank access holes to the surface of the ground.

IMG_0605

As it turned out, the installer hadn’t sealed the joint between the risers and the cement tank with a butyl cord gasket, and the water in the soil was leaking into the tank through the seams.  When I pointed out the mistake, he was quick to dig up the risers and re-install them with the gasket.  Problem solved.  But it made me wonder what would have happened if I hadn’t heard that leak, and muddy water leaked into the tank for months or years.  And it made me wonder how many people ever think to check such things…