I'm considering a few of these for my 914 project and can't really come up with reasons not to try them out. Wiring wise it seems pretty convenient. Cost for a higher quality TEMCo is around $10 ea for a 30 amp rating. You can put whatever size fuse in the slot needed, which also means easy replacement if one pops.
Been using them for a while. Had one that was wonky cause they are chinese after all. But other than that, like most electronics, they fail right away or never.
I like them.
In reply to NOHOME :
Do you know what brand you used? It seems like the True Mods get better reviews than others in the Chinese variety, and the TEMCos seem like a higher end product. If the lower end does the trick all the same I might save a few shekels and go that route.
In reply to captainawesome :
No I don't really recall what I bought. I do read the reviews from suppliers but for what they are worth?
I do have to wonder why this never caught on before or with other suppliers since?
In reply to NOHOME :
That's part of my hesitation in using them. I can't think of any serious downside if used properly but why aren't Bosch making them?
People still use relays without integrated fuses? 
I've used a bunch on my Samurai, they last as long as any other relays in my experience. I've also bought one for the ABS cutoff switch system I'm working on for my Toyobaru.
My custom wiring harness came with fused relays but I can't figure out what brand and the harness is currently 12hrs drive away. Seems great and I wish I had bought them for as long as I've been playing with cars.
Hella makes them. I've been using them in my 2002 for years without issues.
In reply to GameboyRMH :
Total up all the cars, ect. I've put miles on, and I might have had a half dozen failed relays. So I can't quite understand, the "as long as" part, but good to hear they ain't total junk.
I'd never heard of 'em at all before. Cool stuff.
Thinking about this, the fuse is there to protect the load wire going from this relay to the device it powers, and if sized properly for the fuse then things are good there. There may be a failure mode or condition where the load carrying input wire to the relay (so the large wire going in to provide power to the load on the relay) can be shorted to ground through the relay or by the contact coming out of the relay and touching ground, so the load input to the relay really should be protected with a fuse or circuit breaker and sized for that protection.
Meaning, if engineering this for full protection, the load is already protected making the fuse on this relay redundant, unless there's some way to "snap" this relay to a bus bar like in some neat integrated fuse or circuit breaker box. And that's something I've not seen before but I don't deal with this style of relay often so maybe that's a thing? All of the combo fuse & relay boxes I see for cars already have fuses (obviously, the word is right there) making this superfluous. Right?
Short version: I believe the load should already be fused before it gets to the relay or there are odd failure cases where the input power wire, which is unfused, can be driven beyond its amperage capacity and fails.
In reply to pres589 (djronnebaum) :
So for the relays I'll be using, the relay itself will be fairly close to the power source. In this case do you see the same concern as something that's a bit of a distance from the 12 volts?
In reply to captainawesome :
Personally, that depends on how possible it is for the wiring to get chafed.
I'm not much a fan of this style relay for that reason. Or at least, I'm not a fan of the wiring pigtail normally used with this type of relay.
In reply to 03Panther :
I find they also pretty much never fail in most cars, but something about offroading seems to kill them faster. Could be the dirt and submersion
In reply to Pete. (l33t FS) :
So, under this view, ideally, every fuse should have one leg on the battery to be safe?
In reply to captainawesome :
I'd need to see the whole circuit to really give an opinion. Fuse or otherwise protect the load wiring given the size of that wiring. Putting a relay in the middle with a fuse on the top means you have have insufficiently protected wiring. Or you have a duplicate fuse that may not need to be there unless you're trying to step down the size of the load wiring. And I guess that could be a thing, like if you had a 30 amp fuse feeding power to a 16 gauge stranded automotive wire that is a few inches long just to create a break-out from a distribution box or block, and then it hits this sort of relay w/ fuse device, and then if you want to run a couple of yards to a low amperage load you could use 18 gauge with a 5 amp fuse.
My fear is that this could be tied to the battery directly with a couple yards of 10 gauge wire with no fuse between the battery and the relay, and then one of these is used for a long run to the trunk or something, and the installer thinks it's well protected because there's a fuse in the relay. Instead a fuse holder very close to the battery and yadda yadda protect almost all of the run.
NOHOME said:In reply to Pete. (l33t FS) :
So, under this view, ideally, every fuse should have one leg on the battery to be safe?
Again, that boils down to how easily the unfused portion can be chafed.
I've seen battery cables contact ground and partially burn, I've also seen an (unfused) alternator cable overheat and blow all the insulation off before the guy could pop the hood and rip a cable off the battery.
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