Simply EXHAUSTED!

Most bathrooms have exhaust fans in them—or should.

Bathroom Exhaust fan cap

Bathroom Exhaust Fan Cap

Most modern codes (Washington State) require exhaust fans even if there is a window that can be opened. If we do not control moisture levels in our bathrooms, it can not only have a detrimental effect on the bathroom itself, it can also create moisture issues for the rest of the home.  We all know how useful it can be to change the air in the bathroom even if water is not involved.

Who is going to open their window every time they take a shower when it is cold outdoors? Not me.  If you were to do this, you might be surprised at how well it works to lower the humidity in the bathroom, even if it is cold and rainy outside.

Now that I have convinced you of the necessity for bathroom exhaust fans, we need to make sure they are working when we turn them on. Just because the thing shakes, rattles and rolls, does not mean that it pulling any air from the room. Simply turning the fan on is no test of its function.

There are many ways to determine if the fan is pulling any air; and many ways the function can be compromised.

1. The biggest way the function of these fans is compromised is that the user does not use them!

I know this is in the “DUH” category—but it is painfully true.

People need to be taught to turn these fans on, and to leave them on for a set amount of time. Typically I recommend that they be installed on a timer that can be set for various amounts of time and that after showering they be run for 60 minutes. This amount of time can be cut drastically if one raises the temperature in the bathroom itself before taking a shower. Air that is 75 to 80 degree F can contain a LOT of moisture—considerably more than 65 degree air. To the point, even without the fan running, the bathroom mirror may barely fog up if it is hot enough. If you raise the bathroom temperature to 80 degrees F, take your shower, then turn the exhaust fan on for 20 minutes, everything will likely be hunky-dorie in terms of adverse moisture conditions in the bathroom.

We have all taken hot steamy showers in cold bathrooms without fans and then have seen the condensation on the mirror and walls. This can be very damaging to the home (especially modern tight houses), promoting mold/fungal growth on the wetted surfaces. Most bathrooms do not have a “localized” means of heating the bathroom previous to taking a shower, making this not an option. In that case it is best to run the fan the entire time you are showering and for an hour afterwards—assuming the fan is functioning properly.

2. The fans are so noisy they do not get used.

Yes, if every time you take a shower you have to listen to the roar of a jet engine, or feel the house being shaken apart, or make the neighbors complain, there is a good chance the fan will not be used at all.

3. There is no space under the bathroom door.

Many times I see bathroom doors so tight against carpeting that no air can be pulled in under the door to replace the air that the fan is attempting to exhaust. Again, with this installation, no/not enough moist air is removed from the room, making the fan non-functional.

4. There is something restricting the flow of air from the fan to where it terminates at the exterior.

This can be caused by many things—things your home inspector will be looking for. Perhaps the fan motor is running but the squirrel cage has lost its squirrels. Perhaps the damper in the fan unit is stuck closed. Perhaps the vent pipe is crushed, or the end of the vent pipe or outlet of the unit itself is covered with insulation. Perhaps the vent cap damper at the exterior is stuck–maybe blocked with wasp’s nests, paint, debris or other restrictions. Maybe the missing squirrels are living in the vent pipe.

So how does a homeowner test to see if the fan is functional?

Well of course there is sophisticated testing equipment that can be used, but there are less scientific means of determining some degree of function.

1. The paper test.

The paper test can be done on the unit itself—all openings of the fan unit should be fully covered however. Covering only a portion of the opening may not tell you that the air is moving into the unit and then right back out the uncovered part of the cover. If the fan is too high to get to, or the cover is too complicated to cover, you can place the tissue paper right along the bottom edge of the bathroom door on the floor. If the tissue scoots across the floor when you turn the fan on, all that air is going somewhere—and shows that the fan is moving air. (As a side note, if the fan is running and forcefully holding the tissue paper in place, this is a good time to close the bathroom door if it is open.  All of these tests should be done with the bathroom door closed and because if the tissue paper falls off or starts to fall off you will know you have inadequate clearances under the door.)

2. The wet finger test.

If you don’t have any tissue paper you can use the wet finger test. This is kind of like testing to see which way the wind is blowing. You will feel your finger get colder as air is pulled under the door and attempts to dry your finger.  If you feel a good draft with a dry finger, that is an even a more confirming test.

3. The business card test.

If you don’t have a wet finger (it is surprising how resistant people can be to putting their fingers in their mouth) or tissue paper, you can stand up a business card on the floor up against door. It should tip over when you turn the fan on.

While not very scientific, these methods of testing will give you some general information as to function of the fan—at least enough to tell you whether it might be a good idea to have the vent evaluated further. For the best results with this “testing,” make sure that windows are closed during testing and throw a towel or rug over the forced air heat register. These openings can affect how much air is moved from the room—especially the window (The ductwork typically has so much friction losses that it is not often a factor).

Now go back and look at the picture at the top of the post. Can you predict, based on the picture, whether the bathroom exhaust fan moved any air from the room?

Perhaps not so obvious, the screen is keeping the damper closed.

By Charles Buell, Real Estate Inspections in Seattle

If you enjoyed this post, and would like to get notices of new posts to my blog, please subscribe via email in the little box to the right. I promise NO spamming of your email! 🙂

Multi-wire Circuits the Movie

Multi-wire circuits can be confusing to people. 

How multi-wire circuits function, and problems related to them, are important to understand for electrical safety.  In a multi-wire circuit, the neutral (grounded conductor) is shared between two circuits.  Most circuits have their own neutral.  Generally speaking, multi-wire circuits perform just fine as long as the rules of installation are not violated.

Each leg of the multi-wire circuit must terminate on a different bus bar. 

Because bus bars are 180 degrees out of sync with each other, the neutral current can travel on the neutral wire safely.  If they were to terminate on the same bus bar, the current from the two circuits gets added together.  This is because the circuits are no longer 180 degrees out of sync with each other.  Wiring the circuits this way can result in overloading the neutral.  The amount of current leaving the breaker however, would not be more than normal and the circuit breaker would not trip even with the overheating wire.

The following read-along, video-blog attempts to discuss some of these issues.  Please pause or rewind the video where necessary to suit your own level of understanding and learning curve.  The demonstration board is set up to do many more experiments than what this post is about, so pay more attention to the overlays in the presentation and ignore all the rest.  Perhaps some of the other components will show up in a future post.

Charles Buell, Real Estate Inspections in Seattle

 

Bonding grounds and neutrals together in sub-panels

Parallel Paths, be careful

Parallel Paths

One of the most common defects I find related to remote distribution panels (sub-panels) is ground wires and neutral wires bonded together. 

This is especially true if the work has been done by homeowners or handy persons. 

In simple terms, the only place we want to bond the grounds and neutrals together is in the service equipment. Many people refer to it as the “main panel” or a variety of other terms.  

Regardless of what you may improperly call it, the point where you can disconnect all power to the building is the service equipment.  At this point, the ground and neutral are connected to the earth through a system of pipes, rebar, rods, and or wires.  The purpose of connecting the system to earth has little to do with the function of the electrical system.  This provides a layer of protection against lightning surges or static charges that would otherwise build up on the electrical system.

It is a bit like the spark you get from nose to nose when static charges build up on you and the person with the other nose.  This happens because you have no means of sending that excess energy to the earth.

The second important function of all those ground wires running in all the circuits throughout the home is to provide an emergency path back to where they are connected together in the service equipment.  In this way, if there is a short between the energized conductors and some metal component that is grounded, there will be a path back to the point of connection to trip the breaker associated with that circuit.

Circuit breakers trip on heat curves and amperage curves and a short circuit represents many times the amperage rating of the breaker tripping it instantly.  Likewise if there is a problem with the circuit that is resulting in over-amperage, the breaker will trip within the time curve of the breaker–not necessarily exactly the rating of the breaker.  A 20 amp breaker could actually not trip for a few amps above 20 amps for X amount of time without tripping.  Depending on the appliance, the appliance might finish its job before the breaker trips and we would never know it is misbehaving.

But lets get back to not connecting grounds and neutrals together in sub-panels.  Installing the green screw in this sub-panel has resulted in connecting the grounds and neutrals together.  It needs to be removed.

Improper bonding

Green screw bonds the neutral bar to the grounded metal box

When we do bond them together we create two paths back to the connection at the service equipment.  The amount of current that will flow on the two paths will be proportional to the resistance of those paths.  For example if metal conduit or a very large wire is used as the equipment grounding conductor from the sub-panel to the service equipment a large percentage of the neutral current could flow on the bare conduit or bare ground wire (or coated ground wire as the case may be) back to the service equipment.  In some cases the metal conduit might be a proportionally better path than the neutral wire feeding the sub-panel and the majority of the neutral current could then flow on the bare conduit.

I consider it best practice to always provide  a ground wire inside metal conduit but there are probably millions of installations that rely on the metal conduit as the path back to the service equipment.  As long as neutrals and grounds are not bonded together in the sub-panel this is rarely an issue. 

Now if grounds and neutrals are joined together in the sub-panel, the current of all the 120 volt circuits that are operating will travel on the metal conduit, and the neutral wire, as well as the ground wire if present.  This is multiple paths.

So in the following picture where there is no ground wire inside the conduit, but instead the only path back to the service equipment, is the metal conduit, its being disconnected is a serious problem for fire safety and ability of the breakers to trip if there is a fault to ground.  The receptacles of the circuits in this sub-panel tested as ungrounded,.  Fortunately, in this case, the neutrals and grounds were properly isolated, so there was little risk of neutral current running on the bare conduit.

Disconnected electrical conduit

Disconnected conduit feeding condo sub-panel

If they are bonded together in the sub-panel, who is going to be brave enough to grab the two ends of the pipe and stick them back together?

A competent electrician will know enough to test the metal components and/or make sure electrical circuits are turned off, but what about the handyman?  What about your Honey that works on your Honey Do list?  Most people would be unaware of the dangers present and working with the exposed metal components with bare hands could be deadly.

Here is a video demonstration done with students at Bellingham Technical College to show the effect on different size “paths” in a simulation of grounds and neutrals connected together at a sub-panel.  The “light” is the load symbolizing the sub-panel.

A big thanks to Gary Smith for his improvements to this video.

Here is a picture of the wiring diagram for the demonstration in the video:

Charles Buell Real Estate Inspections in Seattle