600V 4A Fuse a replacement for 400V 4A

[Skiroy]

We have a dryer thats down because of a fuse and we need it up ASAP.
We only have a 600V 4A delay fuse when the old one is a 500V 4A fuse.
Is this okay since they are both 4A?

[Al_The_Man]

As long as the open circuit voltage is less than 500v then it is OK.
Al.

[Skiroy]

Okay different fuse question.

I have a 120 VAC to 24VDC Power supply.

Omron S82K-05024 Power Supply 100-240VAC-24VDC/2.1 Amp | eBay

Do I need to put a breaker or fuse on the 120 side going to the PSU or on the 24 VDC side coming off of it going to my terminal blocks for input and output devices. Or do I need both?

This PSU has a a DC on and a DC Low3 light so I dont know if it has built in protection but would I still need to do the the above?

[Al_The_Man]

I usually fit both, but the 120v side would be fused, minimum.
Al.