Fuses

[nmonkman]

What is the primary cause for a fuse failure. Overloading the board or do they just get old. The one that blew is 3 years old.

I have the following hooked up.

CH 1 - 100 ct minis - 12 sets at 2.5 amps

CH 2 - 100 ct minis - 12 sets at 2.5 amps

CH 3 - 100 ct minis - 10 sets at 2.08amps

CH 4 - 100 ct minis - 10 sets at 2.08 amps

CH 5 - 100 ct minis - 14 sets at 2.92 amps

CH 6 - 100 ct minis - 14 sets at 2.92 amps

CH 7 - 100 ct minis - 10 sets at 2.08 amps

CH 8 - 100 ct minis - 9 sets at 1.88 amps

LEFT SIDE TOTAL = 18.96 amps (FUSE THAT BLEW)

CH 9 - 100 ct minis - 9 sets at 1.88 amps

CH 10 - 100 ct minis - 11 sets at 2.29 amps

CH 11 - 100 ct minis - 8 sets at 1.67 amps

CH 12 - 100 ct minis - 6 sets at 1.25 amps

CH 13 - 100 ct minis - 6 sets at 1.25 amps

CH 14 - 100 ct minis - 6 sets at 1.25 amps

CH 15 - 100 ct minis - 4 sets at 0.92 amps

CH 16 - 100 ct minis - 7 sets at 1.57 amps

LEFT SIDE TOTAL = 12.67 amps

Is it possible that the 19 amps on the left side is too close to the max 20. Keep in mind it is not very often that the whole left side is on at once and when it is it is usually only for a couple seconds at best.

[bwaldrep]

Just to confirm, did you upgrade your controller for 20amps, per side?

If you didn't upgrade it, then each side is only 15amps. I'm assuming you did the 20amp upgrade, I just wanted to check.

Also, how positive are you about the amps each channel is pulling? you are really close to 20, so is it possible your numbers are a bit off?

[nmonkman]

Yes, I have the 20 amp upgrade. That is the way the blue board comes.

As far as the actual amps, I have researched that quite a bit so I am fairly certain on those. Of course I just remembered:

The longer the path the more draw.

I am not accounting for a 80 ft 16 awg extension cord.

Perhaps I should just be safe and back off a bit.

[Max-Paul]

Correct me if I am wrong. Incandesent lamps will pull a slight inrush of current. Very small and for a short duration. I just wonder if this is possible what has caused the fuse to blow.

As to your question about fuses ageing. In theory, no. But it is a known fact that at work if we have a 3 phase motor that blew 1 or 2 of the fuses due to a locked rotor. We in practice will replace all 3 fuses. If we have found that if we only replace the blown fuses, that the one good fuse will usually go out shortly. So, in a sense yes a fuse can age as you put it. I would prefer to say that the fuse has been weakened. Thus your fuse might have been weakened by small overloads over time.

[cmoore60]

nmonkman wrote:

Yes, I have the 20 amp upgrade. That is the way the blue board comes.

As far as the actual amps, I have researched that quite a bit so I am fairly certain on those. Of course I just remembered:

The longer the path the more draw.

I am not accounting for a 80 ft 16 awg extension cord.

Perhaps I should just be safe and back off a bit.

Unless you ordered it as a 40 amp controller it comes in the 30 amp model. If you ordered the board with high power heat sinks and put in your own enclosure, then you more than likely have 15 amp fuses.

The color of the board alone is not an indication of the capacity.

Chuck

[Max-Paul]

nmonkman wrote:

I am not accounting for a 80 ft 16 awg extension cord.

Perhaps I should just be safe and back off a bit.

Ah, where is this extension cord at? 16 ga wire I would not load with more than 10A and at 80 feet maybe even back that off to maybe 7 - 8 amps otherwise you will start to see voltage drop. Which as you pointed out will start to cause the device to start to draw more current (well at least in inductive devices).

[Frank A.]

Good morning

follow the link for extension cord ampacity values

http://lightorama.mywowbb.com/view_topic.php?id=20695&forum_id=81&highlight=extension+cord

Frank A.

[Guest wbottomley]

cmoore60 wrote:

nmonkman wrote:

Yes, I have the 20 amp upgrade. That is the way the blue board comes.

As far as the actual amps, I have researched that quite a bit so I am fairly certain on those. Of course I just remembered:

The longer the path the more draw.

I am not accounting for a 80 ft 16 awg extension cord.

Perhaps I should just be safe and back off a bit.

Unless you ordered it as a 40 amp controller it comes in the 30 amp model. If you ordered the board with high power heat sinks and put in your own enclosure, then you more than likely have 15 amp fuses.

The color of the board alone is not an indication of the capacity.

Chuck

That's what I'm thinking Chuck.

[sthobe]

where to get replacement fuses?

[Don]

sthobe wrote:

where to get replacement fuses?

The LOR Store has them for sale. (And you could get them at your local auto/home improvement store as well.)

http://store.lightorama.com/12pafu15afaa.html

[nmonkman]

Radio Shack has them both 15 and 20

http://www.radioshack.com/search/index.jsp?kwCatId=&kw=ceramic%20fuses&origkw=ceramic%20fuses&sr=1

[Mike Cole]

I would recheck your amperage calculations......I use .33amps per 100 count of minis...........Mike

[nmonkman]

Thanks, Mike.



I did that some time ago once I realized I was off a bit.

Thanks for the help though!

[-klb-]

Incandescent inrush is pretty darn quick. Even fast acting fuses are usually slower.

Resistive loads do not increase current with voltage drop in the feed circuit. (thought incandescent loads might increase inrush current or duration)

Different people and experiences seem to have different opinions on how fuses behave in use. Age should not be a significant factor. Some indicate that extended use near their trip point makes them less likely to blow. Others indicate the reverse. Personally, I suspect that the issues actually have more to do with other, non isolated factors.

I will also note that the current drawn by incandescent light strings does go up noticeably when wet. We have had cases where volunteers chained more strings together than they should have. When dry, they worked fine. When wet, they were blowing fuses in the strings of lights.

I would suggest checking the label on your fuse, and use something like a KillaWatt, or clamp meter and 10x adapter to get some solid readings on your loads.

One of the best examples I can think of for unexpected issues was when someone plugged in a string of lights, the circuit breaker in the power strip tripped. We asked who changed what, or plugged what in, and on person said they couldn't believe their short string of lights could be the issue.. Reset things again, and the same issue. Turns out that their short string had a bad plug, that shorted things out... Not everything is always what you think...