Difference between revisions of "Safety"

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== Electricity ==
 
== Electricity ==
  
Electricity in contact with the human body can cause electric shocks which can
+
Most people know that mains electricity is more dangerous than batteries, and that voltages on overhead power cables are more lethal than household mains. Fewer know that some battery-operated equipment can contain voltages more dangerous than mains, and that some mains-operated appliances can contain voltages as hight as on overhead power lines.
* be painful
 
* cause muscles to contract strongly and outside the person's control
 
** (this includes the heart muscles which can stop the heart from working)
 
* heat and burn flesh.
 
  
Pain and muscle contractions can cause a relatively mild shock to have serious consequences e.g. a fall off a ladder.
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There are also risks of fire and explosion if the contacts of high-power batteries (even as small as AA cells) are short-circuited.  
  
The magnitude of a shock depends on the voltage of the source of electricity and the current which flows through the body. The voltage is obviously higher for mains than a small battery. (Batteries can supply enough current to kill a person but conditions mean that their low voltages prevent this happening.) The current which flows through the body depends not only on the voltage applied but the resistance of the skin, clothes and any other objects in its path. The worst case is for wet skin with no clothes which is why mains electricity in bathrooms is particularly dangerous. In contrast a person with dry skin wearing rubber-soled shoes standing on a dry wooden or vinyl-covered floor may hardly notice contact between a finger and a live mains terminal.
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* [[Electricity|More on Electrical Safety]]
  
The severity of a shock, for a given current flowing, depends on the path it takes through the body, and its duration. The worst case is a continuous current following a path from one hand or arm to the other since current is likely to pass through the heart, with grave consequences. A path from a hand or arm to the feet is likely to be less severe. A given current passing for a fraction of second has less severe consequences than a continuous one.
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== Gas ==
 +
By Law you must be '''competent''' to carry out work on gas pipework and appliances.  
 +
[http://www.makewrite.demon.co.uk/GasFitting.html Ed Sirett's Gas Fitting FAQ] is a good guide to those considering doing their own. It is also a useful guide to what to look for and expect from a professional if you decide not to DIY, and explains the various warning notices which can be applied to dangerous appliances and installations.
  
A current in the region of one tenth of an Ampere (amp) is very likely to kill. This is easily available from domestic mains supplies, which are often protected by a Residual Current Device (RCD) which cuts off current in a fraction of a second if it flows outside its proper circuit.
+
=== Other building/DIY work ===
  
The voltages associated with static electricity buildup (e.g. from walking across a nylon carpet) are vastly higher than mains but the current which flows from a static discharge last for such a short time that only a brief pain is experienced. Lightning discharges are also very short-lived but the currents associated with them are so large that they can cause instant death or severe injury through heating and other effects of the huge amount of energy they contain.
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Even where you are not working directly on gas pipework or appliances there are gas-related safety considerations to:
 
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* running electricity cables or electrical fittings near gas pipes
Although mains electricity is obviously hazardous the electronics in battery-operated equipment such as cameras with electronic flash (not the LED flash found on mobile phone cameras) can create lethal conditions. Some mains-operated equipment can store lethal electric charges for hours or days after it is switched off, and some devices store enough energy to create an explosion if parts are short-circuited. A thorough guide to safety in working on electrical equipment (including some battery-operated appliances) is the
+
* removing walls supporting gas pipes, meters or appliances
[http://www.repairfaq.org/sam/safety.htm Sci.Electronics.Repair FAQ '''Safety Guidelines''']
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* changing the ventilation into a room or compartment containing a gas appliance, ''including''
It's worth a read even if you're fairly familiar with and experienced in dealing with electrical & electronic appliances.
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** building an extension onto an outside wall which has a vent for a gas appliance
 
+
* building near a gas flue, ''including''
== Gas Safety ==
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** building an extension on an outside wall, enclosing the flue of a gas appliance ('''dangerous and illegal!''')
[http://www.makewrite.demon.co.uk/GasFitting.html Ed Sirett's Gas Fitting FAQ]
+
* creating a window or vent opening near a flue
 
 
By Law you must be '''competent''' to carry out any gas work! - read this before even thinking of doing your own.
 
  
 
=== LPG ===
 
=== LPG ===
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=== Strong alkalis ===
 
=== Strong alkalis ===
Commonly found in/known as:
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Commonly known as:
 +
* Sodium Hydroxide
 +
* Caustic Soda
 +
 
 +
and found in:
 
* Some drain cleaners
 
* Some drain cleaners
 
* Oven cleaners
 
* Oven cleaners
* Caustic Soda
 
* Sodium Hydroxide
 
  
Contact between strong alkalis and skin is particularly dangerous: whilst acid causes pain immediately alkali can attack skin without causing immediate discomfort and so more damage can be done before it becomes apparent. Alkali damage to eyes can cause loss of sight!
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Skin contact can burn, but irritation occurs before damage, and as long as its rinsed off, no visible damage can be expected.
 +
 
 +
Contact between strong alkali and the eye is particularly dangerous: whilst acid causes pain immediately, an alkali can attack the eye without causing immediate discomfort. By the time discomfort occurs the alkali has entered the eye and serious damage can not be prevented. People have lost their sight this way.
 +
 
 +
Caustic boils and spits when added to hot water.
 +
 
 +
Safety eyewear is recommended when handling caustic soda, and water should be available for rinsing.
  
 
=== Lime ===
 
=== Lime ===
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== Lifting ==
 
== Lifting ==
 
http://www.hsl.gov.uk/images/lifting2.jpg
 
http://www.hsl.gov.uk/images/lifting2.jpg
When lifting heavy loads you should bend your knees and keep your back straight (not legs straight and back bent over the load)
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When lifting heavy loads you should bend your knees and keep your back straight (don't bend over the load with your legs straight)
  
 
For factors involved in lifting to different heights and reaching out carrying loads see [http://www.stannah.com/goodslifts/manual_handling.asp].
 
For factors involved in lifting to different heights and reaching out carrying loads see [http://www.stannah.com/goodslifts/manual_handling.asp].

Latest revision as of 11:22, 11 May 2010

This article needs expanding: please see Discussion page


DIY has an unfortunate relationship with Safety: in hospital A&E departments across the country Easter Sunday - traditionally the most popular time of the year for DIY activities - is known as Bloody Sunday!

Of course nobody intends to have an accident and nobody thinks it can happen to them! When an accident does occur we can sometimes see with hindsight how we could have avoided it: preventing this sort of accident is a matter of cultivating better foresight - taking the time and giving the mental energy to thinking through the job (as not epitomised by Hoffnung's story about a builder and a barrel of bricks!).

However there are many dangers inherent in things in everyday life which are not at all obvious to those without specialist knowledge. For example how many people know that

  • dismantling a battery-operated disposable camera could kill them?
  • mixing toilet cleaners from two different bottles could do so?
  • a circular saw kicks backwards?
  • patio gas can cause a major explosion outdoors?


DIY (and Life in general) doesn't come with any foolproof safety guarantees, but we can stack the odds in our favour by:

  • understanding the science and technology around us
  • learning from the mistakes of others
  • being cautious, and knowing our limitations: sometimes it is more appropriate to get in a professional who has the skills and possibly equipment to do a job safety than to take risks by working outside our own competence. If you are accident-prone then maybe many DIY activities just aren't for you?!

General safety information

Electricity

Most people know that mains electricity is more dangerous than batteries, and that voltages on overhead power cables are more lethal than household mains. Fewer know that some battery-operated equipment can contain voltages more dangerous than mains, and that some mains-operated appliances can contain voltages as hight as on overhead power lines.

There are also risks of fire and explosion if the contacts of high-power batteries (even as small as AA cells) are short-circuited.

Gas

By Law you must be competent to carry out work on gas pipework and appliances. Ed Sirett's Gas Fitting FAQ is a good guide to those considering doing their own. It is also a useful guide to what to look for and expect from a professional if you decide not to DIY, and explains the various warning notices which can be applied to dangerous appliances and installations.

Other building/DIY work

Even where you are not working directly on gas pipework or appliances there are gas-related safety considerations to:

  • running electricity cables or electrical fittings near gas pipes
  • removing walls supporting gas pipes, meters or appliances
  • changing the ventilation into a room or compartment containing a gas appliance, including
    • building an extension onto an outside wall which has a vent for a gas appliance
  • building near a gas flue, including
    • building an extension on an outside wall, enclosing the flue of a gas appliance (dangerous and illegal!)
  • creating a window or vent opening near a flue

LPG

Liquid Petroleum Gas - usually bottled, e.g. camping and patio gas - is heavier than air. Leaks may not be detected by smell since the source of gas is likely to be below nose height, and can accumulate in hollows and drains. Be aware of this when using gas barbecues, patio heaters etc.

Heat and Fire

Plumbing, metalworking and paint-stripping often involve the use of blowlamps. Naturally these involve the risk of setting fire to nearby combustible materials. Vacuuming away loose combustible material from the work area and possibly damping nearby materials with water lessen risks. There are particular risks to soldering pipes close to holes through timber since hot gases from the flame can pass into the hole and ignite the rough end-grain of the wood inside, unseen from the outside. If the air flow is through the hole to the far side smoke may not be seen from the smouldering or burning timber.

Using grinders on many metals also produces streams of hot sparks which can ignite some materials. Since the sparks can fly some distance care needs to be taken not to allow them to fly through gaps e.g. between floorboards where there may be combustible material underneath, out of sight and reach, which can be ignited.

Burning off paint can produce unpleasant and possibly toxic fumes, especially if the paint is old and contains lead.

Bonfires

Dry timber such as old floorboards, joists, laths etc can burn extremely fast and fiercely. If burning such material, especially if closer than 10 metres (30 feet) or so from buildings, trees etc., it is safest to start with a small amount and add more as it is consumed rather than making a pile of it all and setting fire to it. The radiant heat from a large fierce fire can melt plastic drain pipes and set fire to nearby brushwood. Check the surrounding ground: dry grass and twigs etc on the ground may spread the fire. A hosepipe or a sheet (of non-man-made-fibre material) soaked in water can be used to douse grass fires.

Plastics, rubber and other man-made materials emit unpleasant and possibly toxic, even carcinogenous (cancer-causing) smoke and fumes.

Using petrol to start or revive a flagging bonfire is - it is hoped - acknowledged to be hazardous, as petrol rapidly flashes to a burning vapour. However spirits such as methylated spirit are even more dangerous: they flash to burning vapour very rapidly, the flame can spread up an arc of spirit being poured or even thrown towards a fire, the flame is almost invisible and burns with great heat.

Chemical & Biological Hazards

Toilet cleaners

Common toilet cleaning chemicals are based either on bleach or on mild acids: if the two types mix they will generate chlorine gas which can kill in only few breaths! If you smell a strong swimming-pool smell get out into fresh air immediately!

Drain Cleaners

Drain cleaning chemicals are usually strongs acids or alkalis which are extremely dangerous.

Strong alkalis

Commonly known as:

  • Sodium Hydroxide
  • Caustic Soda

and found in:

  • Some drain cleaners
  • Oven cleaners

Skin contact can burn, but irritation occurs before damage, and as long as its rinsed off, no visible damage can be expected.

Contact between strong alkali and the eye is particularly dangerous: whilst acid causes pain immediately, an alkali can attack the eye without causing immediate discomfort. By the time discomfort occurs the alkali has entered the eye and serious damage can not be prevented. People have lost their sight this way.

Caustic boils and spits when added to hot water.

Safety eyewear is recommended when handling caustic soda, and water should be available for rinsing.

Lime

Lime is a weaker alkali which may irritate some skins, and is the component in cement that causes skin irritation. Note that some mortar mixes also contain other alkaline components such as fly ash.

When the job is over, applying vinegar to hands after washing seems to make skin comfortable again much more quickly.

Sewage

Sewage works & pipes contain high levels of bacteria, some of which can be very dangerous to humans if ingested.

  • Observing good hygiene is especially important around sewage
  • When clearing a drain using a pressure washer, wear protection to prevent splashing to eyes, nose or mouth.

Falling Debris

Hard hats should be worn when there is a risk of falling debris.

Lifting

http://www.hsl.gov.uk/images/lifting2.jpg When lifting heavy loads you should bend your knees and keep your back straight (don't bend over the load with your legs straight)

For factors involved in lifting to different heights and reaching out carrying loads see [1].

Steel toe-capped footwear is good when working with heavy loads: apart from reducing danger if the load is inadvertently dropped on a foot it can be useful to use the steel toe-cap as a support when manoevering the load (provided there is no sharp edge which can stray over the cap onto the unprotected foot. Grip-enhancing gloves can also make lifting easier and reduce the risk of dropping.