Protecting against transient blown lighting fuse

My tenants in the shop have called me out for the third time because the lighting fuse blew when they turned on their miniature halogen chandelier and one of the lamps blew at switch-on. To me, continuously blowing fuses means a faulty appliance, and in this case I definitely blame the halogen chandelier. I hate the things. I should never have installed it for them, but they'd already bought it and "it looks sooooo nice!!!".

Anyway, when I rewired the shop 15 years ago all the lighting is in 1.5mm cables. 1.5mm at "clipped direct", "within non-insulating wall", "floor/ ceiling void" is rated at between 16A and 20A. I'm tempted to replace the

5A lighting circuit fuse with a 10A fuse to avoid transient blowing when a halogen blows. Total circuit consumption is 365W of tubes, 15W CFL and 180W of the halogen chandelier, so 2.3A running total. Any comments?

jgh

Reply to
jgh
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Almost certainly the inrush current of the halogens so not really a fault. A 10amp fuse would be a pragmatic solution as would replacing the fuse with a B10 plug in MCB ( if your CU is a suitable type) as they would be able to reset the breaker themselves.

Reply to
Bob Minchin

I'll stick my head above the parapet to give Adam or others something to shoot at.

I don't see anything inherently wrong with a 10A fuse if the Zs is OK

*but* IIRC many (most?) pendants and other domestic fittings are only rated for 6A. And some light switches are only rated for 5A.
Reply to
Robin

Put a dimmer on the chandelier as they usually have soft start so less chance the lamps will blow and take out the fuse.

Reply to
dennis

The lamps will take out the dimmer instead ....

Reply to
Adrian Caspersz

Type C 6A breaker?

Reply to
Tim Watts

But the OP is not running a 10A load:-)

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is a good read. Dunno how old the article (ie table 1) is but I am sure that SBC and SES were all allowed bigger than 6A MCBs in the 17th - I need to double check that though.

Reply to
ARW

Replace the fuse with mcb, or fit a 12v chandelier, or use LED lamps in it. ISTR the 17th allowing 10A circuits with SBC & SES, but check that. There are other options that are more involved, such as a series transformer.

Flashover in halogens is in the region of 60-200A IIRC, so a 10A fuse might or might not prevent the problem mostly, but I don't assume it will.

Isn't it their job to do maintenance like replacing blown fuses?

NT

Reply to
meow2222

Not this one, it is fine for halogens at its advertised rating (I have

200w of GU10 on one without any issues at all).
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Reply to
Toby

OK thanks. Score that as one head splatted.

Yes, I think it's reg. 559.6.1.6 but don't have the final regs to check/quote.

Reply to
Robin

Yup the restriction was removed in the 17th.

Reply to
John Rumm

No dimmer is flashover-proof.

NT

Reply to
meow2222

I gave them a handful of spare fuses, but they ran out.

I've measured the cupboard the CU is in, and replacing the fuseholder with an MCB would stick out so far the door wouldn't close. One thought is to replace the lightswitch with a switch that incorporates an MCB. Wonder if they exist.

jgh

Reply to
jgh

Isnt it their job to sort that?

Not seen them. Baby mcbs are generally thermal only, no good for you. Another option is to put the light fitting on its own low as possible fuse, eg 2A. Use a mains fuse of course, a plug type.

NT

Reply to
meow2222

Don't think so.

Put a separate one in i'ts own enclosure in there for that circuit?

Could you put a FCU in the circuit for that light? Dunno if just replacing the switch would work (as just the live switched normally).

Then they could just use standard plug type fuses (cheaper and easier to get hold of)

Or tell them to get rid of the light !

Reply to
Chris French

Not sure why that is relevant to this part of the thread, if the OP puts that dimmer on, which has soft start, and leaves the 5A fuse in place, I expect it will be enough to prevent the fuse from blowing.

Reply to
Toby

Soft start doesn't prevent filament bulbs blowing, doesn't extend their life significantly and doesn't prevent arcover.

NT

Reply to
meow2222

Soft start does actually extend the life of halogen lamps. You may find you can swap the circuit fuse going for the dimmer fuse (or the dimmer!)

Reply to
John Rumm

It extends halogen life some, but not GLS filament. Halogen capsule lamps are very prone to arc-over, so going that route is not a good strategy. And a bit of life extension doesnt protect against arc-over failures.

If you want protection with filament lamps, you need a series transformer or an electronic solution. Or just a monster relay that can take it!

NT

Reply to
meow2222

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