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earth lift resistors

I have previously been advised to use 100R as earth lift resistors, and have been using wirewound cerramic cased ones rates at 3W with success.

Now an engineer proposes to install a l meg (one meg) 'earth leak' resistor in my valve amp. He says he will bypass this with a 0.1mf capacitor.

Can anyone advise:

i) whether the l meg is as safe as the 100R?
ii) what the purpose of the 0.1uF bypass is and whether it increases safety?
iii) what wattage rating and type of resistor should be used in a valve amp, assuming that 1 meg IS appropriate?
eguth

Showing 1 response by eguth

eguth OP
10 posts
 
Aball

Thanks. That clears it up nicely. I was worried about 'underkill'. I go for overkill as a matter of routine- especially with regard to anything with a safety aspect. I was under the illusion that a very high resistance would be equivalent to almost no earth at all; obviously I was mistaken. Yes I can confirm that the amp is chassis grounded, and now via a 1 meg resistor with bypass.
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