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Meter isolator switch: what sits beside the meter

Updated: October 2026

You are looking at the electricity meter in a UK cupboard and trying to tell the black cut-out from a meter isolator switch you are allowed to use. They sit a few centimetres apart and they do not belong to the same person. The cut-out fuse is the network's. The customer's isolator, if there is one, is on your side of the meter, in the tails that run on towards the consumer unit. This page stays with that boundary and with three 100 A enclosures in the [mains isolation switch comparison](/hub/electrical-equipment/mains-isolation-switch): the WFIS100, the WEC4400 and the WEC440SP. A 13 A plate is the wrong current for this cupboard. There is no lab test.

You are looking at the electricity meter in a UK cupboard and trying to tell the black cut-out from a meter isolator switch you are allowed to use.

Our top picks

WCED WCED WEC440SP

Best overall

WCED WCED WEC440SP
9.2/10about £30.00
View offer
WCED WCED WEC4400

Rank 2

WCED WCED WEC4400
8.8/10about £22.49
View offer
WCED WCED WFIS100

Rank 3

WCED WCED WFIS100
8.6/10about £21.00
View offer
On this page
  1. 1.The fuse in the cut-out is not your switch
  2. 2.Three 100 A enclosures, three different extras
  3. 3.Tails, length and the cabinet
  4. 4.What has to be in the carton

The fuse in the cut-out is not your switch

UK Power Networks' description of a typical domestic supply puts the cut-out and the main fuse with the distributor or the supplier. Only the supplier removes that fuse. An isolator on the customer's side of the meter is the customer's equipment. Pulling the cut-out to make it safe is not using a meter isolator switch. It is interfering with network equipment. A 13 A fused spur in the kitchen does not stand in for this job. The current is wrong, and it does not sit in the tails. In this set the fused switch on the customer side is the WCED WFIS100. Connecting those tails is work for a competent person.

Three 100 A enclosures, three different extras

The WFIS100 is £21.00, with 4.3 from 65 reviews. The bullets include an 80 A fuse, a 100 A fuse and a cable shroud, at 230 V, and the listing cites BS EN 60947-3. The lid can be removed only when the lever is off. The technical table prints 80 A even though the title includes a 100 A fuse, so both numbers stay until you see the carton. The WCED WEC4400 is £22.49, with 4.4 from 14 reviews. A review says it switches three-phase, so it is not the ordinary single-phase house. The WCED WEC440SP is £30.00, with 4.6 from 61 reviews, a 100 A isolator with a Type 2 surge protective device in the same enclosure. The bullet presents that as a BS 7671 arrangement. That is a listing claim. The comparison row says 4 pole, so you match the pole count to the supply.
WCED WCED WEC440SP

Testsieger

WCED WCED WEC440SP
9.2/10about £30.00
View offer

Tails, length and the cabinet

Reviewers of the WEC440SP say 25 mm² tails are awkward, the lower entry does not line up as well as the top, and the enclosure is tight, so they feed it from the top. UK Power Networks' London area has been described as two metres before an intermediate switch-fuse. Confirm the limit with the network that supplies the house. NICEIC, quoting the Energy Networks Association, says a single-pole or double-pole isolator between the meter and the customer's tails may be included. They do not recommend putting a consumer unit in the cabinet. Do not read that note as permission to put the WEC440SP into every meter cabinet.

What has to be in the carton

On the WFIS100, open the carton while the power is still on and the cut-out is still shut, and look for both fuses and the shroud. Reviews mention a missing 100 A fuse, a damaged case, and one unit whose springs were missing, so the house had no power until that was found. On the WEC440SP, confirm you want the Type 2 module and that the tails will enter from the top. On the WEC4400, confirm the supply is three-phase, and reconcile 400 V with 230 V before you order. Lock-off and proving dead, once a competent person is at the isolator, are on the how to isolate electrics safely page.

Common questions

Is the main fuse the isolator?
No. The cut-out fuse belongs to the distributor or supplier. UK Power Networks says only the supplier removes it. Your isolator, where one is fitted, is on the customer's side of the meter. Using the cut-out as a switch is not a DIY method, and a 13 A kitchen spur is not a stand-in for a 100 A tails switch.
What is a 100 A switch for?
It isolates the customer's installation at the meter tails, so work downstream can be done without pulling the network fuse. In this set that means the WFIS100, the WEC4400 or the WEC440SP, from £21.00 to £30.00. It is not the device for a single boiler. The person who connects it has to be competent to work on those tails.
Fused switch or plain isolator?
The WFIS100 is the fused main switch here, with an 80 A fuse and a 100 A fuse in the bullets, and a lid that opens only when the lever is off. The WEC4400 is described as an isolator with sealable lid screws, not as a fused switch, and reviews put it on three-phase. Choose the fused unit when you want those fuse-links in the tails. Check they are in the carton.
Does the SPD enclosure belong in the cupboard?
The WEC440SP puts a Type 2 surge protective device in the same enclosure as a 100 A isolator. The listing aims that at BS 7671 surge protection. The Energy Networks Association guidance quoted by NICEIC allows a single- or double-pole isolator in the cabinet and does not recommend a consumer unit there. It does not say every cabinet may hold this SPD box. Confirm with the local network, and read the tail complaints before you assume it fits.
Why will 25 mm² tails not sit straight?
Reviewers of the WEC440SP say the enclosure is tight, the lower entry lines up worse than the top, and they feed 25 mm² tails from the top. That is a repeated fitting comment, not a measured bend radius. If the tails you have will not enter without force, this enclosure is the wrong shape for that cupboard. There is no instruction leaflet in at least one review.
Is a 4-pole switch for a normal house?
The WEC4400 is 4 pole, with a 400 V bullet, a 230 V table line and a review that says three-phase. That is not the default single-phase house. The WEC440SP comparison row also says 4 pole, at 230 V AC, so you match poles to the supply rather than to the price. A normal single-phase domestic isolator in the ENA note is single pole or double pole.

Related pages

Best mains isolator switch

Mains isolation switch buying guide

Mains isolation switch

How to isolate electrics safely before any UK work

Rotary isolator vs fused spur for one UK appliance

Sources

Public UK sources are listed below. Shelf prices and star lines are the amazon.co.uk figures in the product files. Checked October 2026.

  1. HSE HSR25, Electricity at Work Regulations 1989, regulation 12 (retrieved October 2026)
  2. HSE, work near electricity (retrieved October 2026)
  3. Electrical Safety First, Best Practice Guide 2 issue 4.3 (retrieved October 2026)
  4. IET Wiring Matters, July 2026, Table 537.4 (retrieved October 2026)
  5. IET extractor-fan FAQ (retrieved October 2026)
  6. Approved Document P 2013 (retrieved October 2026)
  7. SI 2012/3119, regulation 12(6A) (retrieved October 2026)
  8. UK Power Networks, a typical domestic supply (retrieved October 2026)