Positive Earth
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=147454
Printed Date: April 18, 2024 at 8:13 AM
Topic: Positive Earth
Posted By: broncoupe
Subject: Positive Earth
Date Posted: September 12, 2022 at 11:48 PM
I feel really stupid I work on negative earth cars no problem. But i have been asked to work on a positive earth classic which they wat to KEEP positive earth. My head just cant work anything out iits a simple wiring issue. The spot lights dont work
1- When testing with my meter do i swop round the red and black leads
2- Are the fuses 12 volt live
3- When i earth the lights to chassis do i get a 12 volt or neg reading
Hope you get my confusion there are relays in curcuit
I keep thinking i will cause a dead short
I really need help
thanks
Replies:
Posted By: geepherder
Date Posted: September 14, 2022 at 6:53 PM
*Allow me to preface what I say with this first: I do not have any experience with a positive ground system.*
That said, from an electrical theory perspective you want to ensure you fuse the negative side of your circuits. Reason being is if you would fuse the positive side and a wire shorted to ground (positive), it would bypass the fuse which would defeat the purpose and could potentially start a fire in the event of an issue.
I suggest just probing around with a meter until you get comfortable.
1) I'd still use red for positive (ground in your case) and black for negative.
2) Fuses should test as negative.
3) The chassis will be positive- I'm not sure I understand your question. If you post a diagram I'm sure we can offer guidance.
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My ex once told me I have a perfect face for radio.
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