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Auxiliary Fuse and Relay panel location


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Thought I'd post this as possible way of installing a panel to give good access a I personally hate struggling to get to things. It's made so it will pull forward to ease of installing the wiring and later maintenance.

Hopefully it will work out. I will update as things go one way or another so people can improve their own efforts if they wish.

Andy

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Very neat job but why such high current fuses? Two of those circuits should be pulling no more than 7-9 amps when running and even allowing for a peak in current on start up the fuses seem over-rated. The horn might be a bit higher depending on the set up, but even then I personally would not have gone above 20/25 amps.

But more importantly you have fitted one fuses upside down and from a purely OCD point of view that would really wind me up :D

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1 hour ago, Red6 said:

Two of those circuits should be pulling no more than 7-9 amps when running and even allowing for a peak in current on start up the fuses seem over-rated.

Good point, plus those modern 30A blade fuses will carry that rated current indefinitely without blowing and will need around 60 A to make them blow in a short time.  

A fuse should be rated to protect the wiring it feeds.  In the case of an overload you want the fuse to blow before the wiring overheats and melts the insulation, so a second or two at most.

What confuses things is the rating of the old Lucas glass fuses which is printed on the circuit schematics and which is around double that of modern fuses, since they are quoting the 'blow' current not the continuous-carry current as is the norm now.  

i.e. where the old drawing says 25A they mean a fuse that will blow quickly at 25A.  For a modern blade-fuse that means one rated at about 12A to 15A.

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11 hours ago, Red6 said:

Very neat job but why such high current fuses? Two of those circuits should be pulling no more than 7-9 amps when running and even allowing for a peak in current on start up the fuses seem over-rated. The horn might be a bit higher depending on the set up, but even then I personally would not have gone above 20/25 amps.

 

8 hours ago, RobH said:

Good point, plus those modern 30A blade fuses will carry that rated current indefinitely without blowing and will need around 60 A to make them blow in a short time.  

A fuse should be rated to protect the wiring it feeds.  In the case of an overload you want the fuse to blow before the wiring overheats and melts the insulation, so a second or two at most.

What confuses things is the rating of the old Lucas glass fuses which is printed on the circuit schematics and which is around double that of modern fuses, since they are quoting the 'blow' current not the continuous-carry current as is the norm now.  

i.e. where the old drawing says 25A they mean a fuse that will blow quickly at 25A.  For a modern blade-fuse that means one rated at about 12A to 15A.

Thanks for the feed back both.

Panic not gents I just pushed three random fuses in so my tiny brain could visualise the circuits better and run the wires to the right spots. Hence all the labels.

Agree the fuses are cheapo rubbish ones. I've had previous experience with these rated at 10A melting everything rather than blowing.:angry: after buying a life supply job lot in a nice box from Machine Mart.

Out of interest who supplies reliable blade and Lucas Fuses that will blow at the stated current?

Andy

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You can't buy blade fuses with a blow rating - only with a continuous current rating.  The rule of thumb is 'times 2'  which is close enough - it isn't an exact science.  i.e. for 20A blow use a 10A rated blade fuse. What you do get is a set of curves showing typical failure time for various overloads as on this datasheet:

https://www.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/blade-fuses/littelfuse_atof_datasheet.pdf

Littelfuse are good for reliable modern fuses - available from RS or Farnell. 

 

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18 minutes ago, RobH said:

You can't buy blade fuses with a blow rating - only with a continuous current rating.  The rule of thumb is 'times 2'  which is close enough - it isn't an exact science.  i.e. for 20A blow use a 10A rated blade fuse. What you do get is a set of curves showing typical failure time for various overloads as on this datasheet:

https://www.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/blade-fuses/littelfuse_atof_datasheet.pdf

Littelfuse are good for reliable modern fuses - available from RS or Farnell. 

 

Thanks Rob

I'll invest wisely this time around.

Andy

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