arniegang wrote:There is a serious safety issue where voltage needs to be increased.
Stepping up from 110/120v to 220/240 V (ac) is not really recommended and carries serious fire/elctrical hazzards.
S/he's stepping down from 220/240 V source to 110/120V for load (appliance).
The risk is when a 110/120V appliance is plugged directly into a 220/240V source. The lower resistance of the appliance will mean a higher current is drawn which will probably overheat the appliance - if you're lucky, the fuse will blow first.
If a transformer is used, then as long as the power rating of the transformer is sufficient for the appliances, there's no abnormal risk. Transformers are used all the time in cars and household appliances without problems most of the time.
If the voltage is not consistant the appliances will blow/fuse as the poster has described.
What
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In particular as the North American electrical products are not "fused" at the source ( ie the plug) then the only safety backup is the fuse within the appliance itself. IF this failed, you are looking at a fire risk.
There should be protection in the main fuse box also. This is not the problem though since the fuse in the plug is usually rated at 13A. Something like a 110/120V stereo is only going to draw 1 A in the US. If you plug it in to 220/240 V without a converter, you'll get 2 A running through which is not going to blow the fuse in the plug but is going to cook your stereo.