Safe to use power tools in garage?

[JohnW2]

Oh that's a good question as i don't have one. Highest power item is the 3kw kettle. I can measure the pssc again when i get the chance as i can't really remember accurately, then you can calculate from that for any theoretical load.

Indeed.

Who knows what would happen if i tried to take the full 80A or whatever.

WEll, with the alleged maximum TN-C-S Ze of 0.35 (presumably at the origin of an installation), you would get a drop ('an additional drop' of 28V - so I suppose the answer (for TN-C-S) would be 'no more than a 28V drop'.

Kind Regards, John

 

[John D v2.0]

Ours is tn-s at the head but i think from memory the Ze is about 0.25 since they replaced the cutout. Anyway I'm still not sure whether i should have dimming lights or not?

 

[JohnW2]

Fair enough i thought you were worried about dinning the neighbours lights being a concern, but who knows which part is too thin.

It wasn't me who was 'worried'. I mentioned that DNOs got concerned about loads with very large start-up currents causing neighbours' lights to dim/flicker (hence 'complaints' that the DNO had to investigate) - and I imagine that it's true for a fairly high proportion of installations that the lion's share of the pre-cutout impedance (i.e. Ze) is attributed to the distribution cables, rather than the cable from it that is feeding the actual installation.

It's theoretically a bit worse with my house, since my two immediate neighbours (whose 'houses' were part of mine up to 1950) share with me the 'final run' of supply cable - but at least it's in what looks like 16mm² singles, which could be worse.

Kind Regards, John

 

[JohnW2]

Ours is tn-s at the head but i think from memory the Ze is about 0.25 since they replaced the cutout. Anyway I'm still not sure whether i should have dimming lights or not?

Well, that obviously depends upon the magnitude of you're vacuum cleaner's start-up current and how sensitive your lights are to voltage fluctuations. With a Ze of 0.25Ω, a, say, 50A start-up current should drop your voltage (very briefly) by 12.5V - but I can't say what that would do to your lights.

For what it's worth, speaking for my place, I've never noticed any lights dimming or flickering when anything 'started up' (and I think that my Ze is {thanks to neighbours TN-C-S and bonding, not my TT } also around 0.25Ω).

Kind Regards, John

 

[John D v2.0]

With a Ze of 0.25Ω, a, say, 50A start-up current should drop your voltage (very briefly) by 12.5V

Let's not confuse the Ze/pefc and the pssc, although they are almost certainly the same in a tn-c-s and similar in a tn-s they aren't quite the same thing.

But your overall point makes sense. With modern led fittings it shouldn't be noticeable, actually the room i was doing the diy with the mitre saw and vac had an old CFL which died recently, and a dodgy looking led Spot light, both in a SES fitting.

 

[JohnW2]

Let's not confuse the Ze/pefc and the pssc, although they are almost certainly the same in a tn-c-s and similar in a tn-s they aren't quite the same thing.

Indeed, and I'm not confusing anything - that's why I've been specifically talking about TN-C-S throughout. With TN-S there is no corresponding rule of thumb that allows one to estimate what one might call Z(L_N) (i.e. supply voltage divided by your 'pscc' {not 'pssc' } )from the allegedly 'maximum TN-S Ze'.

But your overall point makes sense. With modern led fittings it shouldn't be noticeable ...

I think that rather depends upon what sort of 'modern LED fittings' you're talking about. In the case of cheap and nasty (and maybe some expensive!) LED lamps/bubs that use just a capacitor for current control, one might expect them to flicker much more readily in response to fluctuations in supply voltage than would be the case with good-old incandescent bulbs!

Kind Regards, John

 

[John D v2.0]

not 'pssc'

I'm having a short sircuit with that one!