Opening up holes in joist

[pc1966]

Could you not if opening up the hole, drill slightly to one side of it encompassing the existing hole? Especially if it's only 10mm and you drill a 25mm.

That is a good idea. The existing holes are not centred on the beam, they are about 1/3 down, do going below would be a good idea. The beams are 150 years old so bigger than modern cases, but condition along whole length unknown.

 

[Vortigern]

Interested in whether the existing holes comply with Part P, as in what section of the span of the joist are they in? I was just wondering whether the question was a non-starter due to not being in the right place anyway???

 

[loz2754]

Interested in whether the existing holes comply with Part P, as in what section of the span of the joist are they in? I was just wondering whether the question was a non-starter due to not being in the right place anyway???

Good point, except it is not referred to in part P. Part A relates to maintaining the structure of the building.

 

[Dustydazzler]

If the existing holes are very small say 10-15mm but in the place where I need to pull in new cable then I would pull out the old cables , make them bigger and run in my new cables. for the 10mm shower cable I might be tempted to run in its own hole

 

[pc1966]

Interested in whether the existing holes comply with Part P, as in what section of the span of the joist are they in? I was just wondering whether the question was a non-starter due to not being in the right place anyway???

They are not where they should be in the span, at least following UK guidance (the USA has a different figure for distance from end-support as 3*depth, not 0.25*span), but they have been like that since it was rewired in the 90s. But the beams are big and the holes, even if made larger, are a lot less than the max allowed.

My feeling is the least-worst option is opening one hole enough for the additional cable, but going to look at just how wide it would be needed to get the various T&E through without drama (can try-drill some scrap wood to see).

 

[ipf]

They are not where they should be in the span, at least following UK guidance (the USA has a different figure for distance from end-support as 3*depth, not 0.25*span), but they have been like that since it was rewired in the 90s. But the beams are big and the holes, even if made larger, are a lot less than the max allowed.

My feeling is the least-worst option is opening one hole enough for the additional cable, but going to look at just how wide it would be needed to get the various T&E through without drama (can try-drill some scrap wood to see).

After all this lot mate, I'd be reaching for the wood saw, hammer and chisel for notching

 

[ferg]

FWIW I think the Dewalt triflute bits are garbage.
I have a lot of Dewalt gear that is great but the wood bits are absolute guff.
Bosch self feed spade bits are great as are Irwin triflute bits.

 

[nicebutdim]

FWIW I think the Dewalt triflute bits are garbage.
I have a lot of Dewalt gear that is great but the wood bits are absolute guff.
Bosch self feed spade bits are great as are Irwin triflute bits.

I'd noticed Dewalt's bits, but hadn't tried them. Armeg are good, although pricey and I hear mixed reports about their 'nail proof' version - not that I'll be trying them at the current price. Irwin are reltively cheap and last well if you can avoid nails.

 

[Vortigern]

You can sometime use a jigsaw quite safely when cutting away from the wire or maybe a multi tool with a small blade???

 

[pc1966]

FWIW I think the Dewalt triflute bits are garbage.
I have a lot of Dewalt gear that is great but the wood bits are absolute guff.
Bosch self feed spade bits are great as are Irwin triflute bits.

Ah, too late as I got on on my way in to work this morning (different work).

It reminds me of how much I hate working in homes, especially old homes with lath and plaster, etc. Yes, I know if is a valuable job and the bread & butter of most sparks, and would never look down on folks who do this all the time obviously, but I really don't want to be doing this!

But if I don't the friend will probably end up with the plumber doing it...