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What diameter hole do I need to drill for a standard E26 lamp socket nipple? Answered

I live in the UK and am making a lamp for a friend in the US. They are going to fit the socket and wire but I need to drill a hole for the nipple to go through to seat the socket. What diameter hole should I drill to fit a standard E26 brass socket nipple? (I've added a picture to show the kind of socket I have in mind)

Apologies if any of the terminology is off, it's all very different in the UK!

Thanks for your Help!


In the US, the standards for these bits of electrical "plumbing" actually date back to when gas lighting was standardized, since early installations wanted to be able to retrofit gas fittings into electrical by running wires through the existing pipes.

So it *might* actually still be the same in Europe.

But, yeah, the simple answer is to measure the threaded piece and drill a hole just large enough for that to fit through.

Thanks for that interesting piece of info ork!

In response to both you and Lemonie the problem I have is that I don't have the threaded piece to measure!

I have wired up lamps in the UK and the nipples (threaded bit) that I've seen are either 10mm or 1/2". 1/2 inch fits the sockets I use over here and a 14mm hole drilled with a flat bit works, with a nut either side.

I just want to know it that would work for a US socket thread?

Cheers to you both!

Thanks again to Ork and Rick this time, very valuable resources. I figure that 3/8 is the standard for table lamps for you guys so a 1/8IPS nipple is what's required and I'll need to drill the hole just over 3/8" for it all to fit.

I'm usually a pretty handy person... until it comes to maths, then the wheels fall off! thanks again for your help.

I don't know if I'm allowed to do this but can you recommend any stateside stockists of lamp bits?


I agree with them that a standard socket is designed for the 3/8" OD size. Though I've occasionally seen 1/2" when a connection has to carry more/heavier wires or is providing more structural strength. I haven't run into the larger ones, and as they suggest I've only seen 1/4" OD used for support decorative elements such as the finial which secures the lampshade to the top of the harp.

Hope that helps.


Knows everything.

You need to measure the width of the bit that screws into that.
I.e. make the hold just wide enough that the threaded-bit will go through.
Comparing drill-bits usually works.