Kewtech Lightmates - nulling required?

[Soulcraft Electric]

Just been given a set of these and wondered whether the devices themselves need to be nulled as well as the leads? No mention of it in the "manual" that accompanies them so I guess the resistance is negligible. Thoughts?

 

[Pete999]

Just been given a set of these and wondered whether the devices themselves need to be nulled as well as the leads? No mention of it in the "manual" that accompanies them so I guess the resistance is negligible. Thoughts?

None

 

[Deleted member 105166]

Virtually nothing, essentially they "extend" your test leads by just a few mm

 

[SparkyChick]

Given they plug in, I would null the leads as all it takes is a little bit of grime on a contact and you could skew the results a little.

 

[Soulcraft Electric]

Thanks all. Leads only it is.

 

[Octopus]

Had a set for years .... never bothered nulling them

 

[SparkyChick]

I'm not so much thinking the units themselves, but the leads and the contacts where you connect to them. I've yet to use mine for dead testing but based on the variance I can get on my normal leads... anything higher than 0.11ohms and I know I've got potentially got dirty contacts.

 

[Gavin John Hyde]

have never bothered nulling mine, If anything I find that the light mates will likely give a better reading than if nulling leads and probes/clips as it is all to easy to have them not touching just right when nulling and skewing your readings that way. I did see some cheap versions of the kewtech light adaptors on ebay recently and did wonder how good they would be in comparison?

 

[sevuk]

a very useful bit of kit. Great for doing a quick Zs between a dangly and a screw of a switch.
I haven't nulled them for any dead testing, the resistance is negligable, remember we're looking for results within a range to meet certain standards for circuit disconnection times and volt drop. if you're looking to negate such tiny resistances to get the circuit to comply then there's probably cause for concern anyway.

 

[SparkyChick]

I'm thinking nulling for R1+R2 (or equivalent) dead testing only.