fuses

It depends upon the voltage.

Were these lamps connected to the lighting circuit in a house in the UK, the circuit's 6A MCCB would probably accept the connection of an additional 1120W in parallel without protesting.

Were these lamps connected to the supply via a BS1363 13A plug in the UK, then it would be prudent to fit a 3A fuse in the plug.

say for 120,208,220,240,277V 60Hz? because some had designate 5 amps.

1. 4x40W = 160W. Taking the 120V case as one extreme, the continuous load is 160W/120V ≈ 1.4A, say 2.8A for starting. The purpose of the fuse is to protect the wiring. So the fuse size needs to be larger than 2.8A to supply the lamps and small enough to protect all the cables downstream of it and connected to the lamps in the event of a live-to-neutral short circuit.
2. Were the supply 277V, then the continuous load is 160W/277V ≈ 0.6A, say 1.2A for starting. The purpose of the fuse is to protect the wiring. So the fuse size needs to be larger than 1.2A to supply the lamps and small enough to protect all the cables downstream of it and connected to the lamps in the event of a live-to-neutral short circuit.

So a 5A fuse would be OK in both cases provided the wiring is correctly protected by it.

OK with that?

in fusing like HID lamps commonly uses multipliers of about 2.5 of rated current

how about in flourescent? let us say you have 1.2 amps and you used 5 amps fuse

is it not oversized? or maybe i can use 3 amps?

The purpose of the fuse is to protect the wiring. There is no information in any of the above postings on the wiring!

Puhleeasae! When you post such questions, state the country and the circumstances if possible. In the US, we don't normally fuse fluorescent fixtures; we fuse the branch circuit feeding them. Then, it depends only on the AWG of the wiring: 15 A for 14 AWG; 20 A for 12 AWG.

ok here it is. the fuse will protect the four flourescent lamps inside the luminare

so definitely this is fixture wiring. this will be 220v, 60hz

yeah i also knew it that flourescent are not normally fused. it is in the event that a customer will require it. thanks.

so wat is the sized of the fuse? 0.72 amps current

You have OBVIOUSLY not been paying attention! The question has been answered! If you are specifying overload protection for anything other than your own household lights, you are in the wrong line of work!

<...so w[h]at is the sized of the fuse?...>

IT DEPENDS UPON THE SIZE OF THE WIRING! <sigh>

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ok here it is. the fuse will protect the four flourescent lamps inside the luminare

so definitely this is fixture wiring. this will be 220v, 60hz

yeah i also knew it that flourescent are not normally fused. it is in the event that a customer will require it. thanks.

so wat is the sized of the fuse? 0.72 amps current

You must not be subject to Murphy's Law No. 173, Corollary 7:

"The most expensive, highest power semiconductor available, with a 16 month leadtime, will ALWAYS fail just in time to save the 31¢ AGC3 fuse."

Seriously, the fuse will never protect the lamps. The fuse only protects the wiring. If it makes the customer happy, put a 1 A, SB fuse in there, but do check first with the requirements of whatever notified body governs appliance wiring in your part of the world.

I said "slow blow". I meant "time delay". Look at MDA's. Old fart brain at work.

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