16 replies to this topic

[sam138]

I’m currently installing a supercharger to my mini and need some additional ignition power feeds for the below items which I don’t currently have space for on my original fuse box.

- facet solid state orange fuel pump 3-5amp fuse
- Rs components air filter heater element 15w output
- AEM air fuel wide band gauge 3-5amp fuse


Is it possible to add an additional Lucas fuse box with say a 20amp power cable from solenoid and run it to one side of the fuse box looped between 3 connections? This giving 3 ignition power feeds with 5 amp glass fuse on each.

Sorry don’t know a lot about this sort of thing so any help would be great.

Edited by sam138, 03 April 2021 - 09:42 PM.

[lordcakes]

Yes it is possible but running from the solenoid will give you a permanent live feed so you would need a relay to make it switched with the ignition.

If you aren't fussed about a period look then consider a blade fuse box with a busbar (all the lives going to a single feed) or a relay with 3 fused outputs (such as https://www.autoelec...701/category/63)

Edited by lordcakes, 04 April 2021 - 08:06 AM.

[gazza82]

Or take the power from the green cable side of the existing fuse box .. that is a "switched live" feed.

[sam138]

Thanks for the replies, is it perfectly safe to take power from the existing fuse box to a second one ? I can then loop this feed down one side giving the other side switched ignition feeds. If so what sort of amp cable should I use ?

[lordcakes]

You can take power from the existing fuse box, just remember that this additional power will run through the original cables and also through the ignition switch.

Your new feeds are fairly small so it will probably be OK (this depends if you already have additional load running through the system over the factory design?). Realistically, people add all sorts of stuff to their electrical system and there are rarely any massive problems with overloading; the most common problem seems to be light switches and wiring getting tired as they don't have any relays in the circuit as standard (and also aren't fused in the earlier cars).

2mm wire should be sufficient, make sure that you appropriately fuse any circuit that you add. If you want to do belt and braces then consider adding a direct feed from the battery/solenoid with a relay.

Edited by lordcakes, 04 April 2021 - 09:05 AM.

[sam138]

Thanks for the advise, how do you wire up a relay please ?

Is it a feed from Solenoid to relay and a ground earth feed, how do you then connect up to fuse box for ignition power feeds ?

Is this relay ok ?
https://www.halfords...uhoCidMQAvD_BwE

[lordcakes]

That relay would work fine.
Pin 30 - connect to solenoid via in-line fuse (no more than 30A as this is the rating of the relay, ensure wiring can handle any current you are going to pass through it)
Pin 85 - connect to ignition Live
Pin 86 - connect to earth
Pin 87 - connect to your new fusebox

[gazza82]

That relay would work fine.
Pin 30 - connect to solenoid via in-line fuse (no more than 30A as this is the rating of the relay, ensure wiring can handle any current you are going to pass through it)
Pin 85 - connect to ignition Live
Pin 86 - connect to earth
Pin 87 - connect to your new fusebox

Unless you have a diode type relay then it is 86 to live, and 85 to earth. Normal relays work this way too.

[sam138]

Thanks for the help, can I take ignition live (86) from existing fuse box ? Pin 87 does this need loop wiring down one side of fuse box for power feed to each connection?

[lordcakes]

Thanks for the help, can I take ignition live (86) from existing fuse box ? Pin 87 does this need loop wiring down one side of fuse box for power feed to each connection?

Yes you can. This will only be used to trigger the relay so won't add any load onto that fuse box.

If you are using a standard lucas fuse box then you will need to link/loop the terminals down one side of it together.

[sam138]

Thanks, does the solenoid feed connection go on the same side as the black battery cable connection ?

[lordcakes]

Thanks, does the solenoid feed connection go on the same side as the black battery cable connection ?

Yes it can. Just remember to fuse it as close to the connection as possible.

[johnR]

Vehicle Wiring products sell a fusebox identical to the Lucas ones - I used it for my extra feeds

[sam138]

I’ve brought some 17amp red cable to run from Solenoid with 20 amp in line fuse, will also link loop this on fuse box side. Then using 8amp cable from each application to fuse box with appropriate glass fuse.

Should I use 17 or 8amp for the ignition live feed from original fuse box ?

[lordcakes]

Your ignition feed won't be handling any current as it is just to switch the relay so the 8A cable will be fine.

Just a note on fusing - you should always have a fuse that is rated lower than your wire capacity otherwise it might not adequately protect the wiring. If your in-line fuse is a blade fuse, consider a 15A instead.

And remember that blade fuses and glass fuses work in different ways when you work out what rating to use. (there is some information in this post https://www.theminif...to-blade-fuses/)

Edited by lordcakes, 05 April 2021 - 08:21 PM.