Faston Ampacity - Page 1
Forum section: electronics / projects

author: Charybdis
author_rank: Contributor
timestamp: February 24, 2019, 12:51:52 am
content: Hi there, I'm running on a project to update my car lights.I'm planning to run 17 Amp through a 2,5 sq mm (13 AWG) PVC insulated and I'm looking for the proper connectors.I've take a look on TE catalogues as well our italian leaders manufacturers such as Cembre and MTA.So the question is this: how many Amp can a blue 6,35mm faston (.250 series) safely handle ?Thank you so much

author: wraper
author_rank: Unknown
timestamp: February 24, 2019, 01:18:21 am
content: Look into datasheet for particular connector. They use different materials and are rated for different current.

author: Charybdis
author_rank: Contributor
timestamp: March 21, 2019, 06:14:07 pm
content: The problem is that usually that is NOT a parameter listed

author: floobydust
author_rank: Super Contributor
timestamp: March 21, 2019, 07:02:11 pm
content: VDE limits 1/4" Faston to 20A and I have seen up to 40A in automotive parts but I find 25A is reasonable. At 30A up things are pretty hot. It should be fine for headlights or fog lights at 20A.Every connection has resistance and will make heat, the datasheet spec is missing because it depends on how much heat you can get rid of. If the connector is under the hood near the engine, at a relay pin, or is wrapped in insulation (tape, wire loom etc.) it will get hotter and the wire melts.Cheap chinese crimp connectors have very thin metal, so be careful to not use them for high currents.13AWG is pretty stiff to use and it can tug and bend the Faston, with vibration. Blue is 14-16 ga. I would try the yellow ones.Fastons are terrible to make waterproof, so I use Deutsch or Delphi/Packard connectors.

author: wraper
author_rank: Unknown
timestamp: March 21, 2019, 07:38:56 pm
content: Quote from: Charybdis on March 21, 2019, 06:14:07 pmFor example TE lists rated current for every variant. It depends on connector material and intended wire gauge of particular connector. 17A with 2,5mm2is just about what you can get with good quality connector. If there is no data with rated current, it's not a connector you should buy.

author: Charybdis
author_rank: Contributor
timestamp: April 04, 2019, 05:31:40 pm
content: Quote from: wraper on March 21, 2019, 07:38:56 pmActually I've read many technical sheets from AMP, Cembre, BM and TE as well and I never found anything useful. I think I'll go for smth Cembre terminal rated to 110°C and for the wire 2,5 mm2 PVC wire within heatshrink.I found hood temperature is +30°C than outside temp. The worst case scenario is 25°C at night so I think I could manage it. BTW here I give you some extracts of my job researchincluding details of the mentioned connector

author: Monkeh
author_rank: Super Contributor
timestamp: April 04, 2019, 08:25:28 pm
content: TE suggest the limiting factor is the cable, rather than the connector. Considering the substantial contact area, this does not seem unreasonable.

author: Charybdis
author_rank: Contributor
timestamp: April 05, 2019, 08:55:09 am
content: Quote from: Monkeh on April 04, 2019, 08:25:28 pmI'm sorry but I didn't understand your last sentence.Do you mean that using a 2.5 sqmm cable I'll be fine ?

author: Monkeh
author_rank: Super Contributor
timestamp: April 05, 2019, 05:35:09 pm
content: Quote from: Charybdis on April 05, 2019, 08:55:09 amA properly mated 'faston' has much more than 2.5mm2 contact area with fairly substantial pressure. You decide what that implies.

author: Charybdis
author_rank: Contributor
timestamp: April 06, 2019, 02:37:09 pm
content: Quote from: Monkeh on April 05, 2019, 05:35:09 pmReally ? I didn't know that faston were so reliable. That's interesting, thanks !I'll upgrade that line with some 4sqmm then, but I thought I was fine with 2,5 sqmm because I looked in some papers and I found that at ambient temperature of 50-60 °C the ampacity decrease of a 0.7 factor and it goes from 20A to 15A