mcb - may have caused accident - alternative type available?

89 y.o. mother in law is in hospital after falling and breaking her arm. It seems probably that a light bulb failed and the mcb tripped leaving the house in darkness. She then (probably) fell over something and ended up in hospital. I just wonder if there is an alternative mcb available that would not have tripped so quickly (just for the lighting cct)? I see A B and C types but seems they are for higher current overloads rather than slower tripping. (?) advice appreciated. Thanks.
Reply to
dave
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better to try and split lighting circuits amongst mcbs

Reply to
The Natural Philosopher

Mm yes - the house has been wired for some years now - so a big job is that. Still, maybe doable.

Reply to
dave

In the meantime, 2 or 3 of these, strategically placed, should help.

Reply to
S Viemeister

Why not just install some emergency lighting (the type with an internal battery that comes on when the mains fails).

Philip

Reply to
philipuk

I'll wager it was a filament bulb that went 'pop'. It pains me to say it, but some of the better fluorescent/LED bulbs in strategic places would be a cheaper fix. They tend to fail more gracefully & usually without taking the MCB with it.

Phil.

Reply to
Phil

Fitting a few emergency lights around the house would be a better option. Then it won't matter if it goes dark because the MCB has tripped or because somebody has dug through the local supply cable.

Colin Bignell

Reply to
Nightjar

Could you just take the lighting off the MCB? The old girl isn't likely to go up an aluminium step ladder to change a bulb is she?

Bill

Reply to
Bill Wright

So that the house burns down if there is a fault? MCB !=3D RCD.

Philip

Reply to
philipuk

Some sort of emergency lighting fitting? Plenty available (with battery keeps the light on for twenty minutes or half an hour after power failure).

Or CFL (energy saving light bulbs) last longer & less likely to cause a trip.

Reply to
harry

Yup several things you can do here.

A non maintained emergency light or two would be quick and easy - fix to ceiling in strategic places and wire to nearest lighting circuit. If the power fails for whatever reason, they light up.

Splitting a circuit is not necessarily that difficult - it may need one extra wire from a CU and another MCB to do elegantly, however a feed from and adjacent power circuit via a FCU may be a pragmatic option.

Type C MCBs (these have the same thermal trip mechanism as a type B, but a less sensitive "instant" magnetic trip - tripping on 10xIn rather than

5xIn) would probably help, but not guarantee a freedom from tripping in these circumstances.

(one should not go swapping type Bs for Cs willy nilly without checking[1] that fault protection is maintained. However, with the lower ratings of MCB such as the 6A typically used on lighting circuits its unlikely to cause a problem since this only raises the fault current required from 30 to 60A [2]

[1] My measurement or calculation of the earth loop impedance:

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Reply to
John Rumm

tvm all.

Reply to
dave

harry pretended :

Three hours, as a minimum.

Reply to
Harry Bloomfield

I wonder if the OP made the same error as he sort of implied that all the lights in the house went out, and usually there is a sepaeate downstairs and upstairs cct.

1)Not always I know. 2)And the lights that might have helped on the "other" cct may not have been on.
Reply to
Graham.

No idea what its called but I was in a room a couple off months ago when the bulb went. the lady simply reached up, pulled some kind of chord thing and the lamp lowered to an easy reach, then she pulled the chord slightly sideways and it put it back. Weird, but as I have no use for lights I never thought to ask.. Brian

Reply to
Brian Gaff

"rise and fall" light fitting? They used to be popular over dining tables in the 1970s.

Older ones used a long cord and a pulley/counterweight; modern ones have some form of spring mechanism.

Owain

Reply to
Owain

My mother-in-law's kitchen lights are 35W GU10 halogens. When one blows it takes out the fuse and I have to drive over to replace it, every 6 months or so. In my house they trigger the MCBs. The solution is to go back to proper light bulbs that just fail quietly.

Reply to
Geoff Pearson

or stick in a small transformer and swap the lamp to a 20W 12V halogen.

(GU10 mains halogens seem the worst for this - I have seen them even take out a BS3036 rewireable fuse on failure in the past)

Reply to
John Rumm

When I replaced our CU for an MCB based one I noticed a bulb blowing would trip the MCB, whereas previously the fuse remained intact.

My deduction was that given I=V/R, and that when an incandescent bulb blows there is a momentary arc between the broken filament, with an effective resistance of 0, then V/R briefly heads towards "infinity". A normal fuse simply can't blow in that timescale, but an MCB can react.

Problem has since gone away, as we no longer use incandescent bulbs ....

Reply to
Jethro_uk

There are 4 possibilities.

MCBs come in B,C,D types. Using Ds on domestic wiring requires some assessment first. You can also go from 6A to 10A mcb on many lighting circuits, giving more headroom. Whether this approach would avoid the issue I'm not convinced, but perhaps.

Another approach is to get rid of all mains filament and mains halogens, they cause the problem. This is by far the most effective approach.

Another way is to add emergency lighting

A final option is to use plug-in as well as fixed lighting, so if one lot goes off you still have light.

NT

Reply to
meow2222

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