Blowing a Fuse

[wa1es_4_ever]

I bought a new lnb for my sky dish this week an 8 port lnb. Also bought new cable to go with it. I hooked three of my sky boxes up no problem. When i hook the fourth one by screwing the cable into the sky box my 15 amp fuse at the fuse box blows. I changed the wire to another of the lnb ports and yet again my fuse blows. I havent tried it in one of the ports that works yet. Im just wandering could this be a faulty lnb, faulty wire or is it the sky box or could be any of them. Very strange

 

[Lazarus]

Well a short-circuit LNB issue (Faulty LNB, dodgy connection etc) should do no more than cause the eponymous short-circuit protection of the receiver(s) to operate. I cannot see a mechanism that would cause the supply circuit fuse to rupture on excess current.

As you say, strange.

Unless there is a hitherto undiagnosed fault with the fourth Sky box.

 

[bim]

If the same cable has blown 2 fuses it could be faulty cable, not unheard of. Perhaps it was tea break on your real of cable.

 

[BlindFaith]

..you'd better call an electrician to check your 4th sky box ;)

 

[John]

... did some one call me ??.... , does seem a bit strange that the "fault" is not taking out the 3amp or 5amp cartridge fuse within the 13amp plug top first. A re-wireable 15amp fuse type 3036 that you describe as being fitted in the consumer unit, suggesting it to be a radial circuit, is more robust than the plug top fuse even under a short circuit condition and you would normally expect the plug top fuse to take the hit. Replacing the 3036 re-wirable fuse and carrier with a retro fit mcb will make life a bit easier for re-setting the circuit, better still ... incorporate rcd protection for added safety & current regulations requirements. & fitted by a competent registered electrician. I'm not an electronics expert, you need VS, Llew & others for that, but just wondering if either the coax has a short on it, along with the normal current drawn by the lnb into a suspect sat receiver switch mode psu producing a possible near or dead short across the mains input to the receiver ??. Cue the electronics guru's

 

[Channel Hopper]

Are any of 'your' Sky receivers in another dwelling (neighbouring property ?)

 

[John]

....Are you thinking what i think your thinking CH, phase issue ?? ;)

 

[wa1es_4_ever]

No all my receivers are in my house. I was thinking at the moment the cable from lnb to living room is working. if i put the one thats blowing into the port the lnb that i know works and it blows the fuse again then surely the lnb is fine

 

[Lazarus]

Can you confirm that the failing protective device is indeed a fuse? Not an MCB or an RCBO?

 

[wa1es_4_ever]

Its a 15 amp fuse where when blown you have to replace the fuse wire by threading it through.

 

[Lazarus]

Ok, thanks: Just wanted to be absolutely sure as it's not uncommon for old habits to stick around and terms like "fuse" be used for virtually any protective device!

 

[wa1es_4_ever]

Ive now moved the cable to anothe port on the lnb and it all works fine and so far today no fuse has blown. So i can only assume that one or two of this octo lnb are faulty as im using the same cable and the same receiver as yesterday. Thank You to all that replied to my post

 

[Archived-1]

Are you trying to feed each output straight to a STB ?, certain 8 port lnb should go through a splitter should it not ?.

 

[wod]

I think he means an octo lnb rather than one that is used with a multi switch.

More worrying is why the fuse in the plug isn't tripped but the main fuse in the house is.

 

[4wd]

Am no expert in UK mains wiring, but my 1st thought would be some mix-up \ error with earth\live\neutral somewhere in the chain or house, the error getting 'exposed' (by the fuse blowing) when the different sat cable's screening connects all the parts of the setup (parts of the house?) together at the lnb casing. Anything blowing some main fuse, I'd get it checked thoroughly.

 

[timo_w2s]

Yep, a dodgy LNB should not be blowing anything at the fuse board so something is wrong somewhere and I would get your house wiring and satellite setup checked by a qualified electrician ASAP.

 

[bim]

Definately; if it still has the threaded fuse wire fuse type. Don't be tempted to increase the amp wire. I've seen them with 1.5 copper cable installed.

 

[bim]

... did some one call me ??.... , does seem a bit strange that the "fault" is not taking out the 3amp or 5amp cartridge fuse within the 13amp plug top first. A re-wireable 15amp fuse type 3036 that you describe as being fitted in the consumer unit, suggesting it to be a radial circuit, is more robust than the plug top fuse even under a short circuit condition and you would normally expect the plug top fuse to take the hit. Replacing the 3036 re-wirable fuse and carrier with a retro fit mcb will make life a bit easier for re-setting the circuit, better still ... incorporate rcd protection for added safety & current regulations requirements. & fitted by a competent registered electrician. I'm not an electronics expert, you need VS, Llew & others for that, but just wondering if either the coax has a short on it, along with the normal current drawn by the lnb into a suspect sat receiver switch mode psu producing a possible near or dead short across the mains input to the receiver ??. Cue the electronics guru's

On a second thought could it be a loose wire in the wall socket and when the sky box is moved to insert the LMB cable a contact is made in the box causing the main fuse to blow and not the 5amp cartridge fuse in the plug.

 

[John]

timo, bim, agreed .... trapped cable within the back box or socket fixing screw catching a cable, no grommets, sharp edges on back-box fixings etc just needing a bit of pressure on them when pushing the plug top home and bang.... seen 'em all. For complete peace of mind and to end speculation, a thorough inspection / test / upgrade advised by a professional.