Fused or Unfused 2-way plug adaptors?

[winston1]

I’d be more worried about 2 lots of surge protection. In general surges are not a problem in the UK and things like lightning strikes will not be protected by a surge protector.
Surge protectors can cause random RCD trips, two in line can only be worse.

 

[ericmark]

Due to the way this hangs down from the socket

it does not put any great strain on the socket, this

however could, but would depend on weight of cables. Some common sense is required, most units like this

have key hole slots in back so no strain on socket.

As to filtered sockets and surge protection it may remove spikes and could save equipment, but it is hard to say if they work, and when equipment fails it does not put up a label saying I have failed due to a spike on the line, so one simply does not know if they save equipment or not, however they can cause an imbalance between neutral and line so can result in a RCD tripping.

In my house with 14 RCD's (RCBO's which is a MCB and RCD combined) it is unlikely any surge protection device after the RCD will cause them to trip, specially as there is a large surge protection device built into the consumer unit. However where many circuits go through the same RCD then yes extra filters and SPD's may result in more nuisance tripping.

 

[UseLeSsDiYr]

Do I take it that, ecause of 'where things are', it couldn't be done 'the other way around' (since it would perhaps be preferable to have the higher loads on the 'first' one? Howve, even as you propose, I would personally see no problem (there is certainly 'worse' in my house ).
You forgot vacuum cleaners Someone may ask you how you can be sure that no-one will ever do those things, but, if I were you, I would be inclined to ignore them!

Kind Regards, John

Yes - spot on. It is mainly due to where things are at the moment. I can't see total power draw exceeding 2000w on that wall socket.

The hoover did cross my mind, but I can't see anyone kind enough to hoover up my room

On the rare cases I do use the hoover, it would be on the ther circuit (please see my third post), and would not be used with the heater on.

 

[JohnW2]

Due to the way this hangs down from the socket ...... it does not put any great strain on the socket, this ......... however could, but would depend on weight of cables. Some common sense is required, most units like this .... have key hole slots in back so no strain on socket. ....

The OP is talking about 2m extension leads, so all that get plugs in at the 'supply end' is a single plug (attached to a lead) - no different from anything else plugged into a single socket - no your first two photos are irrelevant. The 'other ends' of the extension leads will presumably have the format of your third photo. We haven't been told where they will be (I had guessed probably just 'lying on the floor') but, as you say, even if they were attached to something using their keyhole slots, there wouldn't be a problem.

... so, in relation to the OPs situation and questions, I don't really understand what point you are making?

Kind Regards, John

 

[ericmark]

The OP is talking about 2m extension leads, so all that get plugs in at the 'supply end' is a single plug (attached to a lead) - no different from anything else plugged into a single socket - no your first two photos are irrelevant. The 'other ends' of the extension leads will presumably have the format of your third photo. We haven't been told where they will be (I had guessed probably just 'lying on the floor') but, as you say, even if they were attached to something using their keyhole slots, there wouldn't be a problem.

... so, in relation to the OPs situation and questions, I don't really understand what point you are making?

Kind Regards, John

I plan to plug the extension and the router into the 2-way adaptor, leaving a free slot on the extension lead.

Is this acceptable?

So I had assumed both! As to problems with extension lead feeding an extension lead unless powering a refrigeration unit not really a problem. What one has to remember there is a volt drop across a fuse, but about the only items where volt drop is a problem is fluorescent lights with wire wound ballast and refrigeration motors where unless inverter controlled can stall if volt drop too much.

 

[JohnW2]

So I had assumed both! ...

The second quote you give was "Plan A", back in the OP's initial post, and things have moved a long way (from that plan) since then.

As to problems with extension lead feeding an extension lead unless powering a refrigeration unit not really a problem.

Agreed, which is what I've said. In fact, in the case of the OP's proposed two 2 metre extension leads, I really don't think there would be a problem even if it were feeding a 'refrigeration unit'! You go on to talk about "voltage drop across a fuse" but, again, I really don't think that the VD across one additional 13A fuse would be of any consequence, even for a 'refrigeration unit'.

Kind Regards, John

 

[winston1]

but about the only items where volt drop is a problem is fluorescent lights with wire wound ballast

You have mentioned this a number of times, so much so, that I did some experiments with a Variac and a 65watt florescent with wire wound ballast.

Even down at 205 volts I had no problem with striking or running. Maybe a bit dimmer that's all.

 

[JohnW2]

You have mentioned this a number of times, so much so, that I did some experiments with a Variac and a 65watt florescent with wire wound ballast. ... Even down at 205 volts I had no problem with striking or running.

For what it's worth, I've never hear of anyone other than eric talking about or reporting this problem, either.

 

[ericmark]

You have mentioned this a number of times, so much so, that I did some experiments with a Variac and a 65watt florescent with wire wound ballast.

Even down at 205 volts I had no problem with striking or running. Maybe a bit dimmer that's all.

Interesting the first time I played with voltage on a fluorescent fitting with wire wound ballast was on the building of Sizewell 'B' where my boss had decided to use 110 volt 60 watt fluorescent fittings to light the tunnels.

Quick calculation and we thought approx 0.5 amp each so should get 32 on a 16 amp supply but to be on safe side went for 25. But the 16 amp MCB tripped so we then measured, nearly 21 amp.

On opening the fluorescent fitting it had a standard 230 volt ballast and an auto transformer marked 110 - 0 - 127 and the input was on the 110 side, so swapped first 20 fittings to 127 volt, tried setting all to 127 but last 3 would not strike, and total draw was then around 15 amp. Until then I had not realised how voltage dependent the fluorescent lamp was, but I was around when EU was 220 volt and UK was 240 volt, and that 20 volt was very important with fluorescent lamps, using EU fittings and the tubes were over driven, reducing their life.

But as we dropped officially to 230 volt the old 65 watt 5 foot tubes still worked OK, and as the supply of 65 watt tubes dried up the 58 watt tubes seemed to also work OK, life a little shorter say 18 months where was around 4 years, but the voltage may have been officially 230 volt but in real terms it was over 240 volt, then some houses had solar panels, and the volts dropped, and we actually started to get 230 volt, at that point my kitchen light would strike some times, but not all the time, and I had to move over to LED tubes. I could have used a HF ballast, but would need to remove whole fitting and it was not easy to get to. But it was a combination of wrong tube and lower voltage.

As to refrigeration and volt drop that was Algeria, the Turkish electrician seemed to think 110 volt to neutral 3 phase supply would give 220 volt phase to phase, however it is only 190 volt, and due to the volt drop it would some times stall, and very quickly the overload built into the compressor would fail. And the AC units were requiring repair quite often, cure was to buy them local so designed for the 110 volt system. Most fridges and freezers say do not use an extension lead as a result, the high start load and the resistance of both cable and fuse can cause them to stall.

However my freezer and fridge/freezer today have three phase motors and inverter drive, and the volt drop is no longer a problem, same with the fluorescent lamp the HF ballast auto corrects for volt drop, so tubes last longer, and give out more light, so spec wise compare well with the LED, in my own house the LED did not last long, no SPD so maybe that is why, but one of the few LED failures I have had.

Back in the 90's we had auto transformers built into consumer units claiming to save power by maintaining the voltage to 220 volt so reducing power used, and with a home full of fluorescent lamps they did save money, today they are just a fire risk. Most modern equipment will work 207 to 253 volt, some have a auto disconnect system should the volts go out of that range, solar panels and EV charging points for example. Pre 1995 nominal voltage was 240 volt +6% / -6% so permitted range 225.6 - 254.4 volts Jan 95 this went to 230 volt +10% / -6% so 216.2 - 253 volts and it was proposed Jan 2003 to go 230 volt +10% / -10% so 207 - 253 volts taken from BS7671:2001. And I note with EV charging points the range is 207 - 253 volts so assume that was adopted, together with raising touch voltage from 50 volt to 70 volt.

The volt drop has also impacted on the loop impedance, we have to now allow an extra 5% to allow for volt drop.

I have questioned PAT testing limits where a house is all RCD protected, an extension lead is safe even when rather long with RCD protection but the permitted 2.42 Ω for 13 amp and 16.4 Ω for 3 amp (BS 7671:2008) for a BS 1362 fuse still is required where not RCD on the sockets.

I will admit having had RCD protection on all circuits since around 1992 I tend to expect by now all homes would have it, however with the new landlord laws it seems there are still loads of homes without it. My mothers house only had earths on the lights and all RCD protection in around 2017 and father-in-laws house still had no RCD protection when sold, however as far as this tread goes as long as the adaptors do not cause a strain on the socket I see no problems, all the above is not really required.

 

[JohnW2]

The volt drop has also impacted on the loop impedance, we have to now allow an extra 5% to allow for volt drop.

Eh?

Kind Regards, John

 

[bernardgreen]

that I did some experiments with a Variac and a 65watt florescent with wire wound ballast.

The Variac introduces an inductive component in the supply and thus alters the characteristics of the supply. This could affect the way the florescent lamp fires up.

Dropping the supply using a resistive network would be a better replication of reduced voltage supply.

 

[JohnW2]

The Variac introduces an inductive component in the supply and thus alters the characteristics of the supply. This could affect the way the florescent lamp fires up.

When I first read that, it felt so 'obviously true' that my eyebrows didn't even twitch. However, I then made the mistake of 'thinking about it', and found myself wondering how supplying something via a Variac differs from the usual situation in which they are supplied from the secondary of a transformer in a substation. What am I missing?

Dropping the supply using a resistive network would be a better replication of reduced voltage supply.

That would certainly leave no uncertainties. However, it would require some very meaty 'resistors', so one might well end up using incandescent light bulbs or suchlike.

Kind Regards, John

 

[bernardgreen]

What am I missing?

The distributed resistive and capacitive transmission line between the substation transformer secondary and the lamp.

 

[JohnW2]

The distributed resistive and capacitive transmission line between the substation transformer secondary and the lamp.

What if, hypothetically, the fluorescent light was just 'a few inches' from the substation transformer?

KInd Regards, John

 

[JohnW2]

The Variac introduces an inductive component in the supply and thus alters the characteristics of the supply. This could affect the way the florescent lamp fires up.

When I first read that, it felt so 'obviously true' that my eyebrows didn't even twitch. However, I then made the mistake of 'thinking about it', and found myself wondering how supplying something via a Variac differs from the usual situation in which they are supplied from the secondary of a transformer in a substation. What am I missing?

The distributed resistive and capacitive transmission line between the substation transformer secondary and the lamp.

In an attempt to express my point more clearly ...

I could understand that the behaviour of a fluorescent light (with traditional 'ballast') might be different because a 'low voltage' it was receiving was due to a voltage drop in a series resistance in the current path than if the supply voltage itself was simply low (with minimal VD in the path), as would be emulated by a Variac.

However, I don't see what that has got to do with the Variac "introducing an inductive component" (which is what you suggested as the reason for a potential difference in behaviour) - since, as above, I would think the only relevant difference between the two situations would be the presence/absence of a significant series resistance in the current path.

There is another issue here, which brings me back to the point I repeatedly make about "VD within an installation" being a pretty useless thing to think about - since, for an installation right at the end of the LV supply network, a substantial part of the "voltage drop" will be external to the installation.

In other words, if the voltage coming out of the substation transformer is, say 250V, a fluorescent light receiving, say, 230V will not 'know' whether most of that 20V "voltage drop" is within the installation or nearly all external to the installation (with minimal within-installation VD) - since, in both cases, the total L-N loop impedance would be identical. So, if it were the series resistance which potentially altered lamp behaviour, that would equally arise if that resistance were mainly external to the installation as would be the case if it were mainly within the installation.

Kind Regards, John