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Is it acceptable to solder both poles on each side of a DPST relay so that it becomes a SPST relay with double maximum intensity? The voltage remains the same (230V AC).

I am quite confident that it would work in my case since the relay is already almost good enough: the relay is rated 30A, and I would use it for a 32A (max) appliance. Beside, this appliance doesn't start with a high intensity (soft start), and gets stopped before switching off the relay in normal operations.

But I'd like to know if this is an acceptable practice in the general case. In particular, I don't know if this could cause issues when closing or opening the contacts, since they may not close/open exactly at the same time, could it somehow reduce the relay lifetime or even cause a catastrophic failure? I don't believe over-heating the relay would be possible since the over-intensity time would be very short (the total close/open time is below 10ms).

I'm also interested to know how this would behave in the case the relay fails (at end of life). For example, would this increase fire risks?

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    \$\begingroup\$ @SpehroPefhany you're right, it's a duplicate. I did not find it, I guess the missing keyword was "parallel". Thanks. \$\endgroup\$
    – youen
    Commented Mar 24, 2018 at 10:23
  • \$\begingroup\$ But if you guarantee soft start and soft finish, so no arc , I see no problem. So not a duoplicate question because of your gauranteed specs. \$\endgroup\$
    – D.A.S.
    Commented Mar 24, 2018 at 12:09
  • \$\begingroup\$ When contact resistance increases arc heat increases temperature, wire insulation may turn black and contact current reduces. Either contacts will weld shut or more likely fail to close with sufficient conductance to carry load. It depends on load inductance and arc quench. \$\endgroup\$
    – D.A.S.
    Commented Mar 24, 2018 at 12:21
  • \$\begingroup\$ @TonyStewart.EEsince'75 Indeed, the added guarantees would change the answer, but my question was primarily for the general case : "I'd like to know if this is an acceptable practice in the general case". It appears it is not acceptable in the general case, for the various reasons given on the duplicate question. Also, soft finish is not really guaranteed, for example if mains power stops suddenly, so will the relay, while the load can be in any state. And finally, the relay would be behind a 40A fuse, so it should be able to withstand that. I'll just be safe and use a 40A relay :) \$\endgroup\$
    – youen
    Commented Mar 25, 2018 at 13:52
  • \$\begingroup\$ then your question should not have the implied specific case...."Beside, this appliance doesn't start with a high intensity (soft start), and gets stopped before switching off the relay in normal operations." \$\endgroup\$
    – D.A.S.
    Commented Mar 25, 2018 at 23:22

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