Hot answers tagged

67

Absolutely not safe. Those trusses were engineered with a heavy (critical) dependency on the bottom chords, which are in tension. Removal has left them extremely vulnerable to collapse due to spreading, especially under snow loads, but also under just the load of the roof itself. The roof system is basically a hinge now. To get a good mental image, ...


66

Fire extinguishers (here in the US anyway) are REQUIRED to not be usable after being discharged, partial or not, because you can never know HOW MUCH extinguishing material was discharged by just looking at the pressure gauge. So the valves are designed with breakaway seals that, once broken, will not hold the charge for very long, forcing you to replace it ...


33

If it's a dry chemical extinguisher (seems likely, most common, particularly with a pressure gauge) the simple answer is that the valve has got dry chemical dust in it and no longer seals properly as a result. When refilling the valve or valve parts will either be cleaned or replaced as needed, the dry chemicals will be placed in the container, the valve ...


31

With no bracing above, you might want to check the out side walls - they are probably already spreading. Once they start moving the stabilization and repair can cost many thousands if the roof stays in place, tens of thousands if it comes down. There are ways to mitigate the damage done, but it needs to be done now before the walls spread, the rafters ...


24

An underwater GFCI doesn't matter That is to say, it doesn't perform any useful function underwater. It does nothing to prevent the water from being electrified, which is its one job. Here's how a GFCI is laid out. As you can see, if water can get to the "Line" side of the device, then it electrifies the water. And the GFCI cannot do a thing about it. ...


21

Not only will you need to get your local inspector's approval, in writing (and the inspector will defer to Underwriter's Laboratories or other NRTL, so we're talking about getting a UL listing for your one-off) ... ... But all your thermostat wiring must now be re-done in Class I wiring methods Because you are intermixing thermostat control power with ...


21

While not strictly speaking "single use", I would consider a typical consumer-grade residential fire extinguisher (I have 2 - one on each floor, with the upstairs one near the kitchen) to be a single-use item. This is for a few reasons: Even a moderately sized fire could make good use of the entire extinguisher, so if it is "half used" it is already in the ...


18

The triangle is an extremely stable form of architecture precisely because it has three sides. You remove one side, and you have one of the least stable forms of architecture on account that two members connected at a point can be affected by torque, which is by definition a force multiplier. If you want to play around with it to get a sense, try gluing two ...


12

As pictured - very bad idea. It may work IF the roof is re-engineered to carry a lot more of the stress across the top and bottom of the cutout. That means a much beefier horizontal beam on all four sides of his hole AND a rework of the roof by re-trussing the entire structure. Some examples: This one is a Scissor Truss, and also wears the more ...


10

If you plan to use that collected water for drinking and cooking then you will need a proper filtration / treatment system... Ingesting diluted bird-droppings is not a good idea... So, a simple filter may not be enough, you may well need UV treatment, but you should consult the authorities for the standards in your location you are legislated to meet and ...


9

It sounds like your existing GFCI is not working, pool water (if clean is not really a good conductor) but should have tripped a GFCI prior to tripping a breaker (unless the breaker is a GFCI). The type of pool can make a difference also an in ground concrete/ gunnite or similar pool has a bonding grid that should have tripped the GFCI. A fiberglass in ...


6

If there is a existing C wire for the thermostat (that you could power a commercial smart thermostat with) you can use a non-insulated 24AC to DC converter. Using a bridge rectifier and a switch-mode power supply (plus capacitors as needed). The transformer at the furnace be protected against short circuits. This also immediately means you don't have to ...


6

I'd suggest ear protection, eye protection, and if you're doing a lot of cutting or particularly sensitive to sawdust, dust protection (p95 or better). Steel toe/steel shank boots are generally good on a worksite, but they aren't specific to circular saws. If you are worried about cutting into your legs or worse, you need to think again about how to use a ...


6

You can rent a core drill for under 200 dollars including the dimond bit. You would need to make a substantially larger diameter hole than the pipe because you need concrete around it, not just in it. This is a picture of a very serious bollard https://www.concreteconstruction.net/how-to/creating-a-bollard_o If you are really worried about a teen driver ...


6

Many things are built for a variety of uses. By nature, it cannot be optimized for every use. Compromises are required. That is not a defect; the manufacturer needs to balance all uses of the panel and build something that is ideal for most uses. In particular, the electrician's job can be compromised more, since electricians are professionals who can ...


6

ADA (Americans with Disabilities Act) spec is 33"-36" off the floor for horizontal grab bars. And given 5'-2", I'd lean to the lower end of that scale. Suggest you get one inside and outside the bath at whatever end is used most. ADA.GOV has a lot of good information. (And overkill, like 42" bars at toilets, but I digress.)


6

A metal bucket is much MORE prone to be attacked by acids in general than most plastics, especially those commonly used for buckets. As it's "waste acid" throw in a box or two of baking soda and you'll neutralize it right then and there. Preferably outside due to the release of carbon dioxide. Or use marble/limestone chips or dust.


5

Loose teeth on a modern table saw blade are indeed a thing to be concerned about. It would be anybody's guess as to where the loose tooth would fly if it came off the blade. As many readers here may know the most popular blades in use today are the type with carbide tips bonded to the tooth cutouts on a blade core. It is possible that there is a history of ...


5

First, there is such a thing as a multi-wire branch circuit (MWBC), in which two hots intentionally and consensually shate a neutral. They are placed on opposite poles of service, which means only differential current flows through the neutral. This works for 2 hots in single (split) phase service, and up to 3 hots in 3-phase (208V) service which you will ...


4

A few things that immediately strike me. American plugs have no protection against people or items touching the live pin(s) if the plug is partially withdrawn from the socket. Most European plugs protect against this either through pain insulation or through having the socket at the bottom of the recessed cavity. Until relatively recently the Americans used ...


4

In theory it's not a serious issue. The tooth of a table saw blade travels at a linear speed around 146 feet/second, so if a tooth suddenly came loose you'd be faced with a tiny piece of metal travelling just under 100 mph. In reality the most likely result is it breaks and lodges in the wood when entering the kerf, or exits the kerf and travels straight ...


4

Yes, per anchor unless otherwise specified (and sometimes it is, e.g. in pairs). Accurate? This is advertising we're talking about, and assumes perfect conditions. I'd halve the number given. Regarding your car example, obviously at some point the load will overcome either the structural integrity of the entire drywall sheet (as opposed to the local ...


4

Water and power don't go together. Could it be lethal? The answer is yes. A similar problem occurs at marinas and boat docks, I believe the last I read at least 5 people a year die each year in the US from stray currents causing involuntary muscle spasms leading to drowning. Water breaks down the skin resistance and this makes us more susceptible to shock. ...


4

It's a new problem. First, do anything you want. It's your health and there's no legal mandate, yet. The legionella issue is actually quite new. The disease itself wasn't even identifed until 1976 at the US Bicentennial in Philadelphia, when a bunch of people at a hotel got sick and died. Only this mass-casualty event made anyone notice and start to ...


4

Two possible issues come to mind: The larger screen will not physically fit in the tv wall mount The leverage of the larger screen can tear out the fixings (torque = force * distance).


4

It is also possible that you have a low voltage pool light, in which case the topology would look like line->gfci->transformer->light. The transformer's secondary windings, which produce the voltage going to the pool light, have no reference to ground, and therefore there would be no current leakage through the water into ground, and therefore would not ...


4

Fire extinguishers with plastic heads cannot (or should not) be refilled (recharged)...only metal heads. Plastic heads can split, crack, etc. over time. Either they won’t take a charge or they’ll loose a charge over time.


4

Just a warning: An accident with kilogram amounts of pressurized CO2 in a constrained space could turn that space into an actual "gas chamber" - there could be injuries from losing consciousness and falling, or even death or permanent damage from choking.


4

This sounds like an issue from a physical damage standpoint While the NM cable only needs to be protected by guard strips if it's within 6' of a scuttle hole in your case, as per NEC 320.23(A) (referred to by NEC 334.23): (A) Cables Run Across the Top of Floor Joists. Where run across the top of floor joists, or within 2.1 m (7 ft) of the floor or ...


3

Its not particularly risky, but its not a fantastic idea either. The amounts of current you are talking about pulling is not great, so heat dissipation should nor be an issue. No one will give you a guarantee that it wont catch fire, but it us highly unlikely provided none of the cables have exposed wiring (which might short and spark). Why not use a ...


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