Shower wiring method

JL spark

Don’t shoot me , I’m not a diy Dave , spark by trade , most new builds now don’t have elec showers , have 3 apartments to 1st fix , each has a elec shower back up , 10sq is a pain in the ass to connect in pull cord or switch , how would putting a contractor in consumer unit with a controll circuit ? I was thinking of putting a timer relay to cut contractor after 10 min Incase contractor was left closed ,

Sleeper12

You still need to install an isolation switch within 2 meters of the shower. Why not install a wall switch instead of the pull cord switch? It'll last longer & is easier to wire in than the pull cord switch

2011

I’m not really sure what the timer is supposed to achieve. Either way a contractor is not considered a suitable replacement for an isolator. Depending on a number of factors it may be possible to reduce the cable size between the isolator and the shower to 6 min sq. with the cable from the distribution board to the isolator remaining 10 mm sq. This would make termination less of a challenge.

Webdoctor

2011 wrote: »

I’m not really sure what the timer is supposed to achieve. Either way a contractor is not considered a suitable replacement for an isolator. Depending on a number of factors it may be possible to reduce the cable size between the isolator and the shower to 6 min sq. with the cable from the distribution board to the isolator remaining 10 mm sq. This would make termination less of a challenge.

Is there a regulation on dropping the CSA on a final circuit?

Its certainly not to be recommended for obvious reasons

I see this contactor method of wiring showers is still wrongly being used by some contractors, it
started out as a mistaken recommendation by ECSSA at the time.

2011

Webdoctor wrote: »

Is there a regulation on dropping the CSA on a final circuit?

No.

Its certainly not to be recommended for obvious reasons

It is recommended in some cases. Please share the “obvious reason”.

I see this contactor method of wiring showers is still wrongly being used by some contractors, it
started out as a mistaken recommendation by ECSSA at the time.

Really? I never heard that. Do you have a link to support that?

Webdoctor

Sorry not trying to be smart when I said obvious

When changing a distribution board for example ,you should be able to assume that you are protecting whatever size cable is at the DB and not a smaller cable somewhere on the circuit

I'm nearly say if I go looking there's a reg covering that

Ya, the original idea of wrongly using a contactor to switch the shower load came from ecssa

2011

Webdoctor wrote: »

Sorry not trying to be smart when I said obvious

That’s ok.

When changing a distribution board for example ,you should be able to assume that you are protecting whatever size cable is at the DB and not a smaller cable somewhere on the circuit

Once the smallest cable size is protected you are ok. Take an immersion, generally wired in 2.5 to the immersion switch and 1.5 after it.

I'm nearly say if I go looking there's a reg covering that

Good luck

Ya, the original idea of wrongly using a contactor to switch the shower load came from ecssa

Nothing wrong with that. Contractors are used to switch loads all the time. What would not be permitted is to replace the requirement for an isolator with a contractor.

Webdoctor

The final connection in flexible cable to a fixed load such as an immersion heater is a different matter to the cable from isolating switch to shower.

Yes ECSSA wrongly advised to use a contactor and no local isolation at one time

2011

Just to add people were using contactors to switch loads long before the ECSSA even existed. That includes loads far larger and far smaller than instantaneous showers. Just think of all of the DOL motors and heat tracing loads out there that are switched this way.

2011

Webdoctor wrote: »

The final connection in flexible cable to a fixed load such as an immersion heater is a different matter to the cable from isolating switch to shower.

Why?
Anyway if I am wrong you should be able to show me where the rules state this.

Yes ECSSA wrongly advised to use a contactor and no local isolation at one time

I never heard this but I’m sure you would be able to post a link if this is the case.

2011

I think you have not come across this so you assume it is not permitted. However it is quite common. If there was a rule against this there would have to be a reason behind it in which case you should be able to state that reason.

What is important is to ensure thy all sections of the cable are sufficiently protected, the earth fault loop impedance is low enough and the volt drop is not excessive. After that why would it matter if the final section of cable is smaller ??

Webdoctor

2011 wrote: »

Just to add people were using contactors to switch loads long before the ECSSA even existed. That includes loads far larger and far smaller than instantaneous showers. Just think of all of the DOL motors and heat tracing loads out there that are switched this way.

The shower switch being used for control of a contactor rather than local isolation is the point,which is what ECSSA approved

The cable size should be uniform along its length to the flexible connection if any , dropping size is bad practice at the least imo

Webdoctor

I see you're asking me to prove everything to you which is ok i guess for the sake of argument.

If I decided to use 6sq for a section of the wiring between the distribution board and the pull -cord in the attic and the ends in 10sq is that ok too.

Will the next contractor be expected to check along the length of the cable before deciding whether a shower can be upgraded in size?

Can anyone prove it isn't, maybe they can?

2011

Webdoctor wrote: »

I see you're asking me to prove everything to you which is ok i guess for the sake of argument.

I'm saying that you are making an incorrect assumption.

If I decided to use 6sq for a section of the wiring between the distribution board and the pull -cord in the attic and the ends in 10sq is that ok too.

Subject to certain conditions being met, yes. I have listed the most important of these in my post above.

Will the next contractor be expected to check along the length of the cable before deciding whether a shower can be upgraded in size?

The contractor must check that any is suitable for the load it is being connected to. In the example I described it would be very obvious.

The cable size should be uniform along its length to the flexible connection if any

Why would this only be acceptable if the cable was flexible? In my example would it be acceptable in your opinion if the cable from the isolator to the shower was flexible cable?

Sleeper12

Webdoctor wrote:

If I decided to use 6sq for a section of the wiring between the distribution board and the pull -cord in the attic and the ends in 10sq is that ok too.

This is very common. I've often seen 6mm to the isolation switch but as that could be close to 15 metres max run they use 10mm from the isolation switch to the shower. I've no idea if this is right or wrong but it is common.

Bruthal

2011 wrote: »

I never heard this but I’m sure you would be able to post a link if this is the case.

I think the poster is correct

Usurper.

430.3 and 433.3 are the rules dealing with reduction in CSA on a circuit here

It seems to be allowed and is commonly done of course.

I would be surprised if theres no change for domestic in the upcoming rules as its an unsatisfactory situation for domestic work.