RCDs

snipped-for-privacy@care2.com wrote:

That is another attraction of adding a separate CU so that you can select individual circuits to protect. It leave the option open to move one back to the old CU if required while hunting faults.
If the old install is tripping a 100mA RCD with leakage then it really ought to be fixed as a matter of some urgency anyway since it indicates that there is probably a serious insulation break down failure somewhere.

I don't agree with that as a general statement... you need to take into account the likely users of the installation, and the uses it will be put to.

Just because a shock does not actually kill you it does not mean that you escape unscathed. The RCD protected installation will in many cases reduce the severity of a range of injuries that can be caused by electric shock including burns, arc flash injury, and muscular spasm injury (and secondary injuries resulting from said spasms). Not to mention the pain and distress that shocks can cause.
The number of serious shocks resulting from (mis) using *appliances* is actually quite large - and it is here that 30mA (or lower) threshold RCD protection will make a big impact on prognosis for recovery from the shock.
--
Cheers,

John.

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John Rumm wrote:

Certainly, and this applies to the other causes of death & injury too. Death numbers are the one thing we can quantify and compare, so those are normally what are used for comparison.
If you look at the top killers, electrocution kills orders of magnitude fewer people than a goodly list of other things. I still say spending your pocket money changing an ELCB to an RCD will give little safety return compared to addressing other normal household issues.
A smoke alarm in every room would give way more benefit - look at the govt figures, 70,000 domestic fires a year, 400 annual deaths, and smoke alarms only picking up a percentage of these for various reasons. From Fire Statistics United Kingdom, 2001, ODPM:
"A smoke alarm was absent in the fire area in 59% of dwelling fires in 2001. These fires accounted for around 280 deaths and a further 7,300 non-fatal casualties."
Smoke alarms "failed to operate altogether in 8,100 cases (12%)"

There might be exceptions for unusual uses, but for most of us I dont think thats the prime issue
NT
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snipped-for-privacy@care2.com wrote:

What were the figures of deaths if you include appliance related faults? ISTR the RIA for part P muttered something like 5K before they had to come clean and admit they had used the wrong stats.

These don't have to be "either or" issues - by all means fix the missing hand rail or lose carpet on the top step *and* fit a RCD.

(Tempting to say something about how many of these being caused by electrical faults is unknown ;-)
Yes again smoke alarms good, interlinked ones better, and mains powered even better.

Probably because some muppet had taken the battery out or failed to replace it.

If it was a couple of adults in a first floor flat, then there is very little risk for a RCD to mitigate. A house with kids, or old / infirm inhabitants plus regular use of power tools in the garden etc then the picture is different.
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John.

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